98 results on '"Đurđević, Vladimir"'
Search Results
2. Future changes in extreme precipitation in central Serbia
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Erić Ranka, Kadović Ratko, Đurđević Vladimir, and Đukić Vesna
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future extreme precipitation ,climate changes ,regional climate model ,central serbia ,Hydraulic engineering ,TC1-978 - Abstract
This paper presents the results of a study focused on the projected changes in extreme precipitation during the 21st century in Central Serbia. The changes are investigated on the basis of historical and modelled data sets of daily precipitation. The historical observation data were recorded at 18 synoptic weather stations in Central Serbia and modelled data were extracted from the regional climate model EBU-POM (Eta Belgrade University-Princeton Ocean Model) under the A1B scenario. The average number of days in a year with precipition ≥ 20, 30, 40 and 50 mm (R20, R30, R40 and R50), the share of daily precipitation above the 20, 30, 40 and 50 mm (P20, P30, P40, P50) in the total annual precipitation and the monthly distribution of these heavy daily precipitation are used as indices of changes in extreme precipitation. These indices, for the three periods 2011–2040, 2041–2070 and 2071–2100, are determined and compared with those obtained for the historical reference period 1961–1990. The results have shown that the main changes in extreme precipitation in Central Serbia will be in their spatial distribution, and the uncertainty of the occurrence of extreme events will decrease. In the future the increase will be more pronounced than the decrease of these indices. We strongly emphasize the benefit of this paper for both the prevention of natural disasters in the study area and for the improvement of the regional climate model.
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- 2021
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3. Improving Air Quality Data Reliability through Bi-Directional Univariate Imputation with the Random Forest Algorithm.
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Arnaut, Filip, Đurđević, Vladimir, Kolarski, Aleksandra, Srećković, Vladimir A., and Jevremović, Sreten
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Forecasting the future levels of air pollution provides valuable information that holds importance for the general public, vulnerable populations, and policymakers. High-quality data are essential for precise and reliable forecasts and investigations of air pollution. Missing observations arise when the sensors utilized for assessing air quality parameters experience malfunctions, which result in erroneous measurements or gaps in the dataset and hinder the data quality. This research paper presents a novel approach for imputing missing values in air quality data in a univariate approach. The algorithm employs the random forest (RF) algorithm to impute missing observations in a bi-directional (forward and reverse in time) manner for air quality (particulate matter less than 2.5 μm (PM
2.5 )) data from the Republic of Serbia. The algorithm was evaluated against simple methods, such as the mean and median imputation methods, for missing observations over durations of 24, 48, and 72 h. The results indicate that our algorithm yielded comparable error rates to the median imputation method for all periods when imputing the PM2.5 data. Ultimately, the algorithm's higher computational complexity proved itself as not justified considering the minimal error decrease it achieved compared with the simpler methods. However, for future improvement, additional research is needed, such as utilizing low-code machine learning libraries and time-series forecasting techniques. [ABSTRACT FROM AUTHOR]- Published
- 2024
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4. Impact of UV radiation and temperature on the spongy moth and the brown-tail moth in Serbia
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Milanović, Slobodan, Milanović, Slobodan, Mihailović, Dragutin, Lakićević, Milena, Đurđević, Vladimir, Malinović-Milićević, Slavica, Milanović, Slađan, Trailović, Zoran, Milanović, Slobodan, Milanović, Slobodan, Mihailović, Dragutin, Lakićević, Milena, Đurđević, Vladimir, Malinović-Milićević, Slavica, Milanović, Slađan, and Trailović, Zoran
- Abstract
The impact of climate change on insect pests is an emerging topic in forestry and forest science. This study investigates the relationships between two broadleaved forest pests – spongy moth (Lymantria dispar L.) and brown-tail moth (Euproctis chrysorrhoea L.) – and oaks (Quercus sp.) as their hosts. Oak forests cover almost one-third of the total forest area of Serbia and are ecologicallyvery valuable, but at the same time vulnerable, as being affected in adverse ways by several primary pests and pathogens. Since 1862, Serbia experienced several extremely large outbreaks of spongy moth with more than a hundred thousand hectares completely defoliated each time, while brown-tail moth occurred periodically with a much lower spatial extent. The aim of this research was to investigate the effect of UV radiation (UVR) and air temperature on spongy moth and brown-tail moth in Serbian forests. We used simulations of the coupled regional climate model EBU-POM (Eta Belgrade University-PrincetonOcean Model) for the A1B scenario for the period 2001-2030 as main input and different statistical methods to explore relationships between observations of pest spread and climate change impacts. Our results suggest: (i) increasing the areas affected by spongy moth due to its sensitivity on UVR in May, and (ii) altitudinal spreading of brown-tail moth population up to 800 – 1000 m. This research indicates that in situ forest observations in Serbia are not only affected by climate change, but also by the combined effect of climate on forest pests. For further research, we recommend exploring other forest stressors or dieback phenomena in European forests by applying the same or similar regional climate model dataset.
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- 2023
5. Auswirkungen von UV-Strahlung und Temperatur auf den Schwammspinner und den Goldafter in Serbien
- Author
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Milanović, Slobodan, Mihailović, Dragutin T., Lakićević, Milena, Đurđević, Vladimir, Malinović-Milićević, Slavica, Milanović, Sladjan D., and Trailović, Zoran
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regional climate change effects ,regionale Effekte des Klimawandels ,Temperatur ,Temperature ,Euproctis chrysorrhoea ,UV-Strahlung ,Lymantria dispar ,UV radiation - Abstract
The impact of climate change on insect pests is an emerging topic in forestry and forest science. This study investigates the relationships between two broadleaved forest pests – spongy moth (Lymantria dispar L.) and brown-tail moth (Euproctis chrysorrhoea L.) – and oaks (Quercus sp.) as their hosts. Oak forests cover almost one-third of the total forest area of Serbia and are ecologically very valuable, but at the same time vulnerable, as being affected in adverse ways by several primary pests and pathogens. Since 1862, Serbia experienced several extremely large outbreaks of spongy moth with more than a hundred thousand hectares completely defoliated each time, while brown-tail moth occurred periodically with a much lower spatial extent. The aim of this research was to investigate the effect of UV radiation (UVR) and air temperature on spongy moth and brown-tail moth in Serbian forests. We used simulations of the coupled regional climate model EBU-POM (Eta Belgrade University-Princeton Ocean Model) for the A1B scenario for the period 2001-2030 as main input and different statistical methods to explore relationships between observations of pest spread and climate change impacts. Our results suggest (i) increasing the areas affected by spongy moth due to its sensitivity on UVR in May, and (ii) altitudinal spreading of brown-tail moth population up to 800 – 1000 m. This research indicates that in situ forest observations in Serbia are not only affected by climate change, but also by the combined effect of climate on forest pests. For further research, we recommend exploring other forest stressors or dieback phenomena in European forests by applying the same or similar regional climate model dataset.
- Published
- 2023
6. Circulation weather types and their influence on precipitation in Serbia
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Putniković, Suzana, Tošić, Ivana, and Đurđević, Vladimir
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- 2016
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7. Web application for practicing time management
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Đurđević, Vladimir and Jagušt, Tomislav
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nastavnik ,vrijeme ,school ,TEHNIČKE ZNANOSTI. Računarstvo ,pupil ,učenik ,clock ,očitavanje ,MongoDB ,namještanje ,reading ,TECHNICAL SCIENCES. Computing ,setting ,React ,Express.js ,sat ,teacher ,Node.js ,time ,škola - Abstract
U okviru ovog završnog rada razvijena je aplikacija za vježbanje snalaženja u vremenu. Aplikacija se dijeli na sučelje za nastavnika i sučelje za učenike. Aplikacija se temelji na analognom satu razvijenom pomoću HTML Canvasa kroz koji je omogućeno očitavanje i namještanje vremena. Učenicima se također nudi opcija vježbanja zbrajanja i oduzimanja vremena. U radu su detaljno opisani nastavnikovo i učenikovo sučelje te su opisane sve funkcionalnosti za lakše korištenje. As part of this final exam task, an application for practicing time management was developed. The application is divided into a teacher interface and a student interface. The application is based on an analog clock developed using HTML Canvas through which both reading and setting time are enabled. Students are also offered the option of practicing addition and subtraction of time. The final exam task describes in detail both the teacher's and student's interface and describes all the functionalities for easier usage.
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- 2022
8. Observed Changes in Climate Conditions and Weather-Related Risks in Fruit and Grape Production in Serbia
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Vujadinović Mandić, Mirjam, primary, Vuković Vimić, Ana, additional, Ranković-Vasić, Zorica, additional, Đurović, Dejan, additional, Ćosić, Marija, additional, Sotonica, Dunja, additional, Nikolić, Dragan, additional, and Đurđević, Vladimir, additional
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- 2022
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9. A multi-year study of radioactivity in surface air and its relation to climate variables in Belgrade, Serbia
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Ajtić Jelena V., Todorović Dragana J., Nikolić Jelena D., and Đurđević Vladimir S.
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radioactivity ,beryllium-7 ,lead-210 ,air ,sun-spot number ,climate variable ,Nuclear and particle physics. Atomic energy. Radioactivity ,QC770-798 - Abstract
Activities of 7Be and 210Pb were monitored in surface air in Belgrade, Serbia, from 2004 to 2012. The measurements were taken from two locations, in an open field of a city suburb and in the central city area. The activities were determined on HPGe detectors by standard gamma spectrometry. The 7Be activity shows a pronounced seasonal pattern, with the maximum in spring-summer and minimum in winter, while the 210Pb activity exhibits two maxima, in autumn and late winter. The mean monthly concentrations measured at both sites are below 9 mBq/m3 and 1.3 mBq/m3 for 7Be and 210Pb, respectively. The obtained correlation of the 7Be activity with the number of sun-spots is not statistically significant. Relations of the radionuclides' activities with climate variables (precipitation, temperature, relative humidity, cloud cover, sunshine hours, and atmospheric pressure) are also investigated, but the only significant correlations are found for the 7Be activity with temperature and sunshine hours, and the 210Pb activity with atmospheric pressure. The maximum 7Be and 210Pb activities corresponding to binned total monthly precipitation data imply different modes of the radionuclide scavenging from the atmosphere. During dry periods, accumulation of the radionuclides in the atmosphere leads to their increased activities, but no correlation was found between the activities and the number of consecutive dry days. [Projekat Ministarstva nauke Republike Srbije, br. 43007: Studying climate change and its influence on the environment: impacts, adaptation and mitigation]
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- 2013
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10. Climate change impact on wetland forest plants of SNR Zasavica
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Čavlović Dragana, Obratov-Petković Dragica, Ocokoljić Mirjana, and Đurđević Vladimir
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Zasavica ,wetlands ,forest vegetation ,phyto-geographical elements ,life forms ,climate changes ,Forestry ,SD1-669.5 - Abstract
Wetlands are among the most vulnerable habitats on the planet. Very complex forest ecosystems are also parts of wetlands. Research and analysis of forest vegetation elements, leads to a conclusion about ecological conditions of wetlands. The aim of the paper is detail forest vegetation study, and analyzing the impact of climate changes on wetland forest vegetations of the strict protection area at the SNR Zasavica Ramsar site. Field research was carried out by using Braun-Blanquet’s Zurich-Montpelier school method. Phytogeographical elements and life forms of plants were determined subsequently, in order to get indicator values of wetland plants. Coupled Regional Climate Model (CRCM), EBU-POM was used for the climate simulations. Exact climatic variables for the site were determined by downscaling method. Climatic variables reference values were taken for the period of 1961-1990, and climate change simulations for the period 2071-2100 (A1B and A2). Indicator values of forest plants taken into consideration were humidity and temperature; therefore, ecological optimums were determined in scales of humidity and temperature. Regional Climate Model shows that there will be a long and intensive dry period in the future, with high temperatures from April till October. Continental winter will be more humid, with higher precipitation, especially in February. Based on the analysis of results it was concluded that wetlands are transitional habitats, also very variable and therefore vulnerable to changes. The changes may lead to the extinction of some plant species.
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- 2012
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11. Beryllium-7 activity concentration trends in Serbia and Slovenia
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Bianchi, Stefano, Plastino, Wolfango, Rajačić, Milica, Krneta Nikolić, Jelena, Todorović, Dragana, Zorko, Benjamin, Nečemer, Marijan, Vodenik, Branko, Glavič Cindro, Denis, Kožar Logar, Jasmina, Sarvan, Darko, Đurđević, Vladimir, Ajtić, Jelena, Bianchi, Stefano, Plastino, Wolfango, Rajačić, Milica, Krneta Nikolić, Jelena, Todorović, Dragana, Zorko, Benjamin, Nečemer, Marijan, Vodenik, Branko, Glavič Cindro, Denis, Kožar Logar, Jasmina, Sarvan, Darko, Đurđević, Vladimir, and Ajtić, Jelena
- Abstract
Beryllium-7 is a natural radionuclide used as a tracer of the stratospheric-tropospheric exchange. Its abundance in the surface air is expected to change as the temperatures in the atmosphere increase. To investigate the temporal trends of the beryllium-7 activity concentrations and temperature, we apply spectral analysis to time series from three sampling sites: Belgrade in Serbia, and Ljubljana and Krško in Slovenia. The sites lie close to the 45 ºN parallel, with Krško approximately 400 km and Ljubljana around 500 km west of Belgrade. Between January 1991 and December 2019, the air filter samples were collected using air samplers; a monthly composite sample was formed and analysed by gamma spectrometry. We use monthly mean temperature records from the European Climate Assessment & Dataset, the Republic Hydrometeorological Service of Serbia for Belgrade, and the Slovenian Environment Agency for the sites in Slovenia. In the spectral analysis decomposition, we look into a term called trend that represents the overall growth (increase or decrease) in the data records. The trend is calculated using a linear fit. All three sites show 1) positive temperature trends, however statistically insignificant (at the 95 % confidence level), and 2) statistically significant beryllium-7 activity concentration trends of 2.26 %/year, 1.13 %/year, and 0.50 %/year in Belgrade, Ljubljana, and Krško, respectively. The results confirm our initial hypothesis–over the 28 investigated years, the beryllium-7 activity concentrations increase in the surface air. On the other hand, the non-significant temperature rise in our records suggests that within our method, the temporal resolution of one month is insufficient for obtaining a statistically significant temperature trend.
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- 2022
12. Observed Changes in Climate Conditions and Weather-Related Risks in Fruit and Grape Production in Serbia
- Author
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Vujadinović Mandić, Mirjam, Vujadinović Mandić, Mirjam, Vuković Vimić, Ana, Ranković-Vasić, Zorica, Đurović, Dejan, Ćosić, Marija, Sotonica, Dunja, Nikolić, Dragan, Đurđević, Vladimir, Vujadinović Mandić, Mirjam, Vujadinović Mandić, Mirjam, Vuković Vimić, Ana, Ranković-Vasić, Zorica, Đurović, Dejan, Ćosić, Marija, Sotonica, Dunja, Nikolić, Dragan, and Đurđević, Vladimir
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Climate change, through changes in temperature, precipitation, and frequency of extreme events, has influenced agricultural production and food security over the past several decades. In order to assess climate and weather-related risks to fruit and grape production in Serbia, changes in bioclimatic indices and frequency of the occurrence of unfavourable weather events are spatially analysed for the past two decades (1998–2017) and the standard climatological period 1961–1990. Between the two periods, the Winkler and Huglin indices changed into a warmer category in most of the viticultural regions of Serbia. The average change shift was about 200 m towards higher elevations. Regarding the frequency of spring frost, high summer temperatures and water deficit, the most vulnerable regions in terms of fruit and grape production are found alongside large rivers (Danube, Sava, Great and South Morava), as well as in the northern part of the country. Regions below 300 m are under increased risk of high summer temperatures, as the number and duration of occurrences increased significantly over the studied periods. The high-resolution spatial analysis presented here gives an assessment of the climate change influence on the fruit and grapes production. The presented approach may be used in regional impact assessments and national planning of adaptation measures, and it may help increase resilience of agricultural production to climate change.
- Published
- 2022
13. Characteristics of radioactivity in the surface air along the 45°N zonal belt in South-Eastern Europe
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Ajtić, Jelena V., Zorko, Benjamin, Nečemer, Marijan, Sarvan, Darko Z., Rajačić, Milica, Krneta-Nikolić, Jelena D., Todorović, Dragana, Đurđević, Vladimir S., Vodenik, Branko, Glavič-Cindro, Denis, Kožar Logar, Jasmina Koar, Ajtić, Jelena V., Zorko, Benjamin, Nečemer, Marijan, Sarvan, Darko Z., Rajačić, Milica, Krneta-Nikolić, Jelena D., Todorović, Dragana, Đurđević, Vladimir S., Vodenik, Branko, Glavič-Cindro, Denis, and Kožar Logar, Jasmina Koar
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This study investigates the beryllium-7, lead-210 and caesium-137 activity concentrations in aerosol filter samples collected monthly along the 45°N zonal belt over 1991–2019. Sampling was performed in three locations, one in Serbia and two in Slovenia, and the Slovenian data records are published here for the first time. The activity concentrations were determined by standard gamma spectrometry. The obtained results are in general agreement with the literature data for Europe. The data sets at different sites display similarities in measurement ranges, overall means and seasonal cycles. Still, statistical tests show significant differences among the radionuclides’ concentrations across the locations. To investigate underlying processes that affect radioactivity in the surface air in this region, multivariate statistical concepts are applied to the radionuclides’ concentrations and local meteorological parameters. Discriminant analysis shows that all three sites are well separated from each other. Principal component analysis gives common pattern of interconnection between the observables: temperature has a stronger influence on the behaviour of beryllium-7 and lead-210 than that of caesium-137, but a negative correlation of the radionuclides’ concentrations with precipitation seems the strongest for caesium-137. Principal component analysis also shows local differences in the degree of relationship between the meteorological parameters and activity concentrations of the investigated radionuclides. This is an important finding for future atmospheric transport studies.
- Published
- 2021
14. Changes in long-term properties and natural cycles of the Danube river level and flow induced by damming
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Stratimirović, Đorđe, Stratimirović, Đorđe, Batas-Bjelić, Ilija, Đurđević, Vladimir, Blesić, Suzana, Stratimirović, Đorđe, Stratimirović, Đorđe, Batas-Bjelić, Ilija, Đurđević, Vladimir, and Blesić, Suzana
- Abstract
In this paper we assessed changes in scaling properties of the river Danube level and flow data, associated with building of Djerdap/Iron Gates hydrological power plants positioned on the border of Romania and Serbia. We used detrended fluctuation analysis (DFA), wavelet transform spectral analysis (WTS) and wavelet modulus maxima method (WTMM) to investigate time series of measurements from hydrological stations in the vicinity of dams and in the area of up to 480 km upstream from dams, and time series of simulated NOAA-CIRES 20th Century Global Reanalysis precipitation data for the Djerdap/Iron Gates region. By comparing river dynamics during the periods before and after construction of dams, we were able to register changes in scaling that are different for recordings from upstream and from downstream (from dams) areas. We found that damming caused appearance of human-made or enhancement of natural cycles in the small time scales region, which largely influenced the change in temporal scaling in downstream recording stations. We additionally found disappearance or decline in the amplitude of large-time-scale cycles as a result of damming, which changed the dynamics of upstream data. The most prominent finding of our paper is a demonstration of a complete or partial loss of annual cycles in the upstream stations' data that stems from the operation of the artificial water reservoir and extends as far as 220 km from dams. We discussed probable sources of such found changes in scaling, aiming to provide explanations that could be of use in future environmental assessments.
- Published
- 2021
15. Climate change within Serbian forests: Current state and future perspectives
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Stojanović, Dejan, primary, Orlović, Saša, additional, Zlatković, Milica, additional, Kostić, Saša, additional, Vasić, Verica, additional, Miletić, Boban, additional, Kesić, Lazar, additional, Matović, Bratislav, additional, Božanić, Danijela, additional, Pavlović, Lazar, additional, Milović, Marina, additional, Pekeč, Saša, additional, and Đurđević, Vladimir, additional
- Published
- 2021
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16. Assessment of climate change risks to natural resources in the republic of Serbia
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Duškov, Ljubica, Filipović, Dejan, and Đurđević, Vladimir
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forest ,climate change ,Republic of Serbia ,Raska Administrative District ,Vulnerability ,risk assessment ,agriculture - Abstract
A temperature rise, extreme weather conditions and its consequences negatively impact the quality of life in towns and regions in Serbia and are challenges yet to be faced in the future. In order to prepare the country more adequately to altered climate conditions, as well as the successful implementation of adaptive measures, it is necessary to determine the vulnerability, as well as the assessment of the risks to certain sectors to climate change. Estimates show that since 2000 the Republic of Serbia has faced several significant extreme climate and weather events that have caused the loss of human life, considerable material consequences and degradation of the natural environment. The consequences have been various depending on the part of the country and the paper uses as an example the Raska Administrative District which covers an area of 3.918 km(2) and has 309.258 residents. The aim of the paper is to assess the vulnerability and assessment of the risks of natural resources (agricultural and forest land) of the Raska Administrative District to climate change based on methodology 'FUTURE CITIES Adaptation Compass' [1], developed as part of the EU Project FUTURE CITIES. Using the results of 9 different models for the RCP 8.5 scenario, the paper concluded that agriculture and forests would be at a very high risk of heat waves, droughts and extreme precipitation, as well as under the medium-level risk of extreme cold. The research has a applicative character as it represents the starting point in the process of adapting to climate change. Also, the result of the paper has significant impact on planning spatial development because the defining of planned solutions must be in correlation with possibilities for adapting the sector to different climate conditions, and thus the realistic concept of spatial development.
- Published
- 2020
17. Seasonality of 7Be concentrations in Europe and influence of tropopause height
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Hernández-Ceballos, Miguel Angel, Brattich, Erika, Cinelli, Giorgia, Ajtić, Jelena, Đurđević, Vladimir, Hernández Ceballos, Miguel Angel, Brattich, Erika, Cinelli, Giorgia, Ajtić, Jelena, and Djurdjevic, Vladimir
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Europe ,7Be ,Radiotracers ,Tropopause height ,transport time ,seasonality ,tropopause height ,lcsh:Meteorology. Climatology ,lcsh:QC851-999 ,radiotracer ,radiotracers - Abstract
This study aims at analysing the latitudinal variability of both the yearly and seasonal pattern of 7Be surface activity concentrations, at addressing the impact of tropopause height (TPH) on 7Be distribution and at evaluating the time lag between TPH and 7Be at European level. With this aim, weekly 7Be and daily TPH data at 17 sampling stations during 10 yr (2001–2010) are analysed. 7Be shows a clear increasing tendency in the period and generally tends to increase with decreasing latitude. The seasonal pattern generally shows maxima during the warm period and minima during the cold one. The seasonal variogram analysis points out a good spatial correlation for TPH data while a weaker one is observed for 7Be, having TPH a larger influence on 7Be during summer. The influence of TPH on 7Be exhibits a large spatial variability, with a clear gap between south and north in the area of the polar front jet. The results identify the presence of two main groups, in particular separating between stations located in northern Europe (50 °N and higher) and stations in southern Europe (south of 50 °N). A similar behaviour for stations located in the same geographical area is also observed when looking at the day of maximum impact of TPH on 7Be concentrations. The results suggest that 7Be concentrations respond in different time ranges to changes in the TPH, observing seasonal differences in each group. These results represent the first European approach to the understanding of the TPH impact on 7Be concentrations at surface levels.Keywords: 7Be, radiotracers, tropopause height, transport time, seasonality, Europe(Published: 11 May 2016)Citation: Tellus B 2016, 68, 29534, http://dx.doi.org/10.3402/tellusb.v68.29534
- Published
- 2016
18. Validating AquaCrop model for rainfed and irrigated maize and soybean production in eastern Croatia
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Marković, Monika, primary, Josipović, Marko, additional, Jančić Tovjanin, Milena, additional, Đurđević, Vladimir, additional, Ravlić, Marija, additional, and Barač, Željko, additional
- Published
- 2020
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19. The potential impact of climate change on the distribution of key tree species in Serbia under RCP4.5 and RCP 8.5 scenarios.
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Miletić, Boban, Orlović, Saša, Lalić, Branislava, Đurđević, Vladimir, Mandić, Mirjam Vujadinović, Vuković, Ana, Gutalj, Marko, Stjepanović, Stefan, Matović, Bratislav, and Stojanović, Dejan B.
- Subjects
CLIMATE change ,MULTIPURPOSE trees ,FOREST ecology ,HABITATS - Abstract
Copyright of Austrian Journal of Forest Science / Centralblatt für das Gesamte Forstwesen is the property of Osterreichischer Agrarverlag Druck und Verlags Gesellschaft m.b.H. Nfg. KG and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2021
20. Analiza uticaja aktivnosti sunca i meteoroloških parametara na koncentraciju 7Be u prizemnom sloju atmosfere
- Author
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Todorović, Dragana, Puzović, Jovan, Đurđević, Vladimir, Rajačić, Milica, Todorović, Dragana, Puzović, Jovan, Đurđević, Vladimir, and Rajačić, Milica
- Abstract
Zbog svoje radioaktivne i toksične prirode, lokacije i načina nastajanja, izotop 7Be ima višedecenijsku pažnju u oblasti radioekologije i meteorologije, pre svega kao trasera u praćenju kretanja polutanata i vazdušnih masa. Shodno tome, bilo bi poželjno ustanoviti model vremenske distribucije ovog izotopa, koji bi omogućio predikciju njegove koncentracije. Kao doprinos poboljšanju odabira parametara za simulacione modele, cilj ovog istraživanja je da se ispita uticaj aktivnosti Sunca i pojedinih meteoroloških parametara na koncentraciju 7Be u prizemnom sloju atmosfere. Za potrebe ovog istraživanja, korišćeni su rezultati gamaspekrtometrijskog odreĎivanja koncentracije aktivnosti 7Be u dva medijuma (vazduh – uzorci aerosola i ukupni depozit) tokom perioda 1995–2017, sprovedenih u Laboratoriji za zaštitu od zračenja i zaštitu životne sredine, Instituta za nuklearne nauke “Vinča”. Metodama Furijeove transformacije i linearne regresije, primenjenim u ovoj disertaciji, po prvi put je uočena mogućnost uticaja smera Sunčevog magnetnog polja na koncentraciju 7Be u uzorcima vazduha. Pokazalo se da bi uključivanje perioda promene od 22 godine moglo dovesti do poboljšanja kvaliteta njene simulacije., Due to the 7Be isotope is radioactive and toxic nature, as well as its location and way of its production, it has decades of attention in the field of radiochemistry and meteorology, primarily as a tracker in monitoring the movement of pollutants and air masses. Accordingly, it would be desirable to establish a time distribution model for this isotope, which would allow a prediction of its concentration. As a contribution to improving the selection of parameters for simulation models, the aim of this study is to examine the influence of solar activity and individual meteorological parameters on the concentration of 7Be in the ground level atmosphere. For the purposes of this research, the results of gamaspekrtometric determination of the activity concentration of 7Be in two media (air - aerosols and total deposit) were used. They carried out at the Laboratory for Radiation Protection and Environmental Protection, Institute for Nuclear Sciences "Vinča" and cover the period during 1995-2017. The methods of the Fourier transform and linear regression, applied in this dissertation, for the first time have seen the possibility of influencing the direction of the Solar magnetic field to the concentration of 7Be in air samples, and it has been shown that the inclusion of a period of change of 22 years can lead to a decline in the quality of its simulation.
- Published
- 2019
21. Vijabilnost populacije tekunice (Spermophilus citellus) pod uticajem promene klime i staništa
- Author
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Milić, Dubravka, Ćirović, Duško, Bjelić-Čabrilo, Olivera, Marković, Vladimir, Đurđević, Vladimir, Nikolić, Tijana, Milić, Dubravka, Ćirović, Duško, Bjelić-Čabrilo, Olivera, Marković, Vladimir, Đurđević, Vladimir, and Nikolić, Tijana
- Abstract
U radu je analiziran odgovor lokalnih populacija tekunice u Vojvodini na promene uslova klime i korišćenja zemljišta. Odgovori populacija tekunice (tipičnog predstavnika otvorenih staništa i idealnog model organizma) na pomenute promene omogućiće razmatranje kako mere na regionalnom nivou: i) mogu unaprediti zaštitu i očuvanje tekunice ii) ublažiti efekti promene klime i korišćenja zemljišta iii) mogu usaglasiti razvoj poljoprivrede sa očuvanjem biodiverziteta travnatih ekosistema. Kako bi se odgovorilo na pitanja i postavljene hipoteze u radu sprovedeno je terensko istraživanje, korišćen standardni prostorni pristup i ekološko modelovanje. Sve primenjene tehnike su komplementarne jedna drugoj u dobijanju odgovora na postavljena pitanja gde rezultati jedne analize predstavljaju ulazne podatke za drugu analizu. U tezi su korišćeni podaci dobijeni na osnovu terenskog mapiranja lokalnih populacija i podaci iz eksperimenta modelovanja kao i serija podataka dobijena cenzusom kolonija tekunica i terenskim uzorkovanjem zemljišta i vegetacije. Rasprostranjenje populacija oblikuju klimatski uslovi ali pored abiotičkih faktora uslovljavaju ih i biotički faktori i kretanje jedinki. Promena klime direktno utiče na distribuciju optimalnih uslova. Istraženo je u kojoj meri će doći do promene u distribuciji optimalnih uslova sredine za tekunicu. Potencijalna promena analizirana je uzimajući u obzir klimatski scenario Max Plank Instituta sa tri rcp projekcije i tri generisana prostorna scenarijadistribucije otvorenih travnatih staništa u Vojvodini. Sagledavanje mogućih efekata promene sredinskih uslova dalo je mogućnost da se ukaže na zone koja će biti ključne za očuvanje populacija tekunica i travnatih ekosistema u Vojvodini. Sledeće, s obzirom da disperzija jedinki, dostupnost resursa kao i delovanje lokaln, The study analyzes the European ground squirrel (EGS) population response to land use and climate change in Vojvodina. The response of the EGS population (typical species of open grassland habitats and the ideal model organism) to changes in environmental conditions in this region will enable consideration of following measures at the local and landscape level: i) effective protection and conservation of the EGS and habitat it relay on; ii) climate change and land use mitigation and adaptation iii) how can we harmonize the development of agriculture and preserve the biodiversity of grassland ecosystem in agricultural settings. In order to answer the questions of this study, the field research was conducted, standard spatial approach and ecological modeling were employed. All applied techniques are complementary to one another in obtaining responses to the questions asked. The results of one analysis represent the input data for the following one. The data for the study were obtained: from EGS local populations’ field mapping, from the modeling experiment, the census campaigned and the field sampling of soil and vegetation. Distribution of populations, which in addition to abiotic factors are conditioned by biotic factors and movement of individuals were evaluated in the context of climate change. Climate change directly affects the distribution of optimalconditions. The potential changes in distribution of optimal environmental conditions for EGS were assessed by considering changes in abiotic factors and the availability of grasslands. The climate scenario obtained using a dynamic vegetation map with three rcp projections and three spatial scenarios for the distribution of open grasslands were used. The extrapolation of a suitable area obtained by presence only model Maxent gives the possibility to point to the zones that will be crucial f
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- 2019
22. Analysis of trends, periodicities, and correlations in the beryllium-7 time series in Northern Europe
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Bianchi, Stefano, Plastino, Wolfango, Brattich, Erika, Đurđević, Vladimir, Longo, Alessandro, Hernandez-Ceballos, Miguel A., Sarvan, Darko, Ajtić, Jelena, Bianchi, Stefano, Plastino, Wolfango, Brattich, Erika, Đurđević, Vladimir, Longo, Alessandro, Hernandez-Ceballos, Miguel A., Sarvan, Darko, and Ajtić, Jelena
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The activity concentrations of beryllium-7, a natural radiotracer that is considered as a tracer of the strato-spheric-tropospheric exchange, shows a distinct behaviour in Northern Europe compared to the central and southern parts of the continent. In this study, we use the measurements collected at four sampling stations in Scandinavia (Ivalo, Umea, Kista, Risoe) between 2001 and 2010 and investigate their trends, periodicities and residuals with the aim to further understand the common features in the beryllium-7 data records in northern sampling sites. The beryllium-7 activity concentrations exhibit statistically significant positive trends that range from an average value of 1.50%/year to an average value of 2.96%/year. We detect a one-year periodicity in all the sites, and in the southernmost site, Risoe in Denmark, additional higher-frequency harmonics. In the residual time series, we find outliers that represent occurrences of extremely high beryllium-7 activity concentration. Cross-correlations of the beryllium-7 residuals across the four sites decrease with increasing distance; similarly, as indicated by local Hurst exponents the records exhibit long-range correlations that weaken towards the end of the investigated period. To investigate the causes of the detected trends, we also calculate correlations between beryllium-7 and factors related to its production, transport and removal from the atmosphere: in particular, cross-correlations of the beryllium-7 residuals with residuals in sunspot number, local temperature, atmospheric pressure and precipitation, as well as Arctic Oscillation index and North Atlantic Oscillation index. Most of the obtained correlations, however, are not statistically significant, highlighting the need to analyse a longer time period in order to evaluate the impact of different factors on the airborne beryllium-7 activity concentration.
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- 2019
23. Temporal and spatial distribution of the beryllium-7 activity concentration in the surface air in Europe
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Ajtić, Jelena, Đurđević, Vladimir, Saravan, Darko, Brattich, Erika, Hernández-Ceballos, Miguel-Angel, Zorko, Benjamin, Todorović, Dragana, Ajtić, Jelena, Đurđević, Vladimir, Saravan, Darko, Brattich, Erika, Hernández-Ceballos, Miguel-Angel, Zorko, Benjamin, and Todorović, Dragana
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- 2019
24. Behaviour of beryllium-7 and lead-210 time series measured in Serbia and Slovenia over 1991-2015
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Sarvan, Darko, Todorović, Dragana, Rajačić, Milica, Krneta-Nikolić, Jelena D., Đurđević, Vladimir, Zorko, Benjamin, Vodenik, Branko, Glavič Cindro, Denis, Kožar Logar, Jasmina, and Ajtić, Jelena
- Abstract
VI International Conference on Radiation in Various Fields of Research : RAD 2018 : book of abstracts; June 18-22, 2018; Ohrid, Macedonia
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- 2018
25. Expected Changes of Montenegrin Climate, Impact on the Establishment and Spread of the Asian Tiger Mosquito (Aedes albopictus), and Validation of the Model and Model-Based Field Sampling
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Petrić, Mina, primary, Lalić, Branislava, additional, Pajović, Igor, additional, Micev, Slavica, additional, Đurđević, Vladimir, additional, and Petrić, Dušan, additional
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- 2018
- Full Text
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26. Faktorska analiza specifičnih aktivnosti berilijuma-7 i olova-210 u prizemnom sloju vazduha, i meteoroloških parametara
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Ajtić, Jelena, Sarvan, Darko, Todorović, Dragana, Rajačić, Milica, Krneta-Nikolić, Jelena D., Đurđević, Vladimir, Zorko, Benjamin, Vodenik, Branko, Glavič-Cindro, Denis, and Kožar Logar, Jasmina
- Abstract
Međusobna povezanost specifičnih aktivnosti berilijuma-7 i olova-210 u prizemnomsloju atmosfere sa meteorološkim parametrima razmotrena je u faktorskoj analizi.Merenja su sprovedena u Beogradu, Republika Srbija, i u Ljubljani i Krškom, uRepublici Sloveniji, tokom 1991–2015 godine. Na sve tri lokacije, faktorska opterećenjadva faktora pokazuju da je: 1) specifična aktivnost berilijuma-7 obuhvaćena faktorom 1sa temperaturom, oblačnošću i relativnom vlažnošću; dok je 2) specifična aktivnostolova-210 obuhvaćena faktorom 2 sa količinom padavina i atmosferskim pritiskom.Iako je komunalitet već dva faktora veći od 0,5 za većinu posmatranih varijabli, tekuvođenjem trećeg faktora komunalitet za specifičnu aktivnost olova-210 i atmosferskogpritiska na sve tri merne lokacije raste na preko 0,5. Rezultati faktorske analizepokazuju da se specifične aktivnosti berilijuma-7 i olova-210 u prizmenom slojuatmosfere nalaze pod različitim dominantnim uticajima. Koncentracija berilijuma-7 jepod uticajem faktora regionalnog karaktera, koji je takođe dominantan za srednjutemperaturu. Ova veza specifične aktivnosti berilijuma-7 i temperature preko dominantnog zajedničkog faktora važi i kada se broj faktora u analizi poveća na tri i četiri.Sa druge strane, na koncentraciju olova-210, kao i na količinu padavina i atmosferskipritisak, više uticaja ima lokalni faktor. Ova povezanost olova-210 sa druga dvameteorološka parametra, međutim, prestaje da važi sa povećanjem broja faktora uanalizi na tri, kada se izdvaja specifičan faktor koji objašnjava preko 80% varijansespecifične aktivnosti olova-210. An association between the beryllium-7 and lead-210 specific activities in surface airand meteorological parameters is investigated using factor analysis. The measurementswere conducted in Belgrade, Republic of Serbia, and Ljubljana and Krško, Republic ofSlovenia, over 1991–2015. In all the locations, the factor loadings of two factors showthat: 1) the beryllium-7 specific activity is encompassed by factor 1 together withtemperature, cloud cover and relative humidity; while 2) the lead-210 specific activity,precipitation and atmospheric pressure are described by factor 2. Although thecommunalities of only two factors are already larger than 0.5 for most of the variables,an introduction of a third factor raises the communalities of all the variables above 0.5.The results imply that the beryllium-7 and lead-210 are under different dominantunderlying mechanisms. The concentration of beryllium-7 seems to be primarilyinfluenced by a mechanism of a regional character which is also a predominant factorfor temperature. This association between the beryllium-7 specific activity andtemperature prevails even when the number of factors in the analysis is raised to threeand four. The lead-210 specific activity, on the other hand, together with precipitationand atmospheric pressure, is under an influence of a local mechanism, but thatrelationship between the variables ceases to hold when the number of factors is raisedto three, and more than 80% of the variance in the Pb-210 specific activity is explainedby one specific factor.
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- 2017
27. Simulierte Langzeitveränderungen von Umweltbedingungen und Graslandvegetation in drei Schutzgebieten in Serbien
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Čavlović, Dragana, Beloica, Jelena, Obratov-Petković, Dragica, Đurđević, Vladimir, and Košanin, Olivera
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climate change ,ddc:580 ,habitat suitability index ,VSD+ model ,plant community simulation ,sh85015976 Botany ,Serbian grasslands - Abstract
Intense direct and indirect human pressure has been imposed on grasslands throughout their range. Mostly due to the constant need for more food production or due to changes in environmental conditions, grasslands as habitats are expected to become highly endangered. The aim of this study was to estimate the grasslands’ ecological response to future climate and environmental changes. The study took place in three ecologically different grassland communities in three protected natural areas of Serbia (Southeastern Europe), following the same methodology. The study sites were: 1) Peštersko polje Special Nature Reserve (SNR), 2) Deliblato sands SNR (its southern part: Labudovo okno) and 3) Zasavica SNR. Climate change was simulated for mean temperatures and precipitations using the Eta Belgrade University-Princeton Ocean Model (EBU-POM) climate model, for the A1B Intergovernmental Panel on Climate Change (IPCC) emission scenario covering the 1951–2100 period and insolation and volumetric soil moisture content for the 1979–2100 period. Grassland vegetation was analysed at all three sites. One representative plant community per site was selected for further analysis and simulation of ecological changes. One plot was positioned inside each of the above-mentioned communities, all vascular plant species inside the plot were recorded, and soil samples were taken. Ecological Optima (EO) for moisture and temperature were calculated from modified Ellenberg’s plant indicator values of recorded species. The plants’ response to climate and environmental changes was simulated using the VSD+ model for the 2010–2100 period. The data obtained from the model were further analysed with Canonical Correspondence Analysis (CCA). Overall results show that the temperature rise, along with the irregular precipitation at all three sites, will lead to a drop of the relative abundance of many native species in the period between 2040 and 2060. The low obtained Habitat Suitability Index for the future means that there will be either unfavourable environmental conditions for the development of grasslands, or the species we analysed were untypical. Cosmopolitans and xerothermic species will be more accustomed to the new conditions. Grasses will be the most resilient functional group according to our study. It may be concluded that the functional group of grasses will also play the leading role in future grasslands at the studied sites. In Serbien sind vor allem natürliche Grasländer stark gefährdet. Bislang liegen nur sehr wenige Studien zur Auswirkung von Klimaveränderungen auf Grasländer in Serbien vor (z. B. BELOICA et al. 2015). Zudem wurde die Biodiversität des Graslands in Südosteuropa bislang insgesamt kaum untersucht (DENGLER et al. 2014). Das Ziel dieser Studie ist ein Beitrag zur Kenntnis, inwieweit Pflanzengesellschaften auf veränderte Klimabedingungen reagieren. Die Untersuchung wurden in drei Schutzgebieten in Serbien durchgeführt; untersucht wurden drei ökologisch verschiedene Graslandgesellschaften. Die drei Untersuchungsgebiete waren das Peštersko polje-Special Nature Reserve (SNR), das Delibater Sande-SNR (dessen südlicher Teil zum Gebiet Labudovo okno gehört) und das Zasavica-SNR. Zunächst wurde die Graslandvegetation der drei Gebiete analysiert. In jedem Gebiet wurde eine repräsentative Pflanzengesellschaft ausgewählt um die ökologischen Veränderungen zu simulieren. Die ökologischen Optima der Arten hinsichtlich Feuchte und Temperatur wurden auf Grundlage von Zeigerwerten (nach KOJIĆ et al. 1997) berechnet. Die Bodeneigenschaften wurden an den gleichen Orten bestimmt, wo die Aufnahmen erstellt wurden. Die Namen der Pflanzenarten entsprechen der EURO+MED-Datenbank und die Habitattypen EUNIS. Die Veränderungen der mittleren Temperatur und des mittleren Niederschlags nach dem A1B-(IPCC 2014)-Szenario wurden auf Grundlage des Zeitraums 1951–2100 mit Hilfe von EBUPOM-Klimamodellen simuliert. Die Einstrahlung und der volumetrische Bodenwassergehalt wurden auf Grundlage des Zeitraums 1979–2100 simuliert. Die Reaktion der Pflanzen auf die Klima- und Umweltveränderungen wurde mit Hilfe von VSD+ (Version 5.5, 2001, 2015 Alterra, CCE; MOLDIJKSTRA & REINDS 2017) für den Zeitraum 2010–2100 simuliert. Eine kanonische Korrespondenzanalyse der Pflanzengesellschaften für denselben Zeitraum wurde mit Hilfe von Past 3.14 (HAMMER et al. 2001) durchgeführt.
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- 2017
28. Factor analysis of the beryllium-7 and lead-210 specific activities in surface air, and meteorological parameters
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Ajtić, Jelena, Sarvan, Darko, Todorović, Dragana, Rajačić, Milica, Krneta-Nikolić, Jelena D., Đurđević, Vladimir, Zorko, Benjamin, Vodenik, Branko, Glavič-Cindro, Denis, and Kožar Logar, Jasmina
- Abstract
Međusobna povezanost specifičnih aktivnosti berilijuma-7 i olova-210 u prizemnom sloju atmosfere sa meteorološkim parametrima razmotrena je u faktorskoj analizi. Merenja su sprovedena u Beogradu, Republika Srbija, i u Ljubljani i Krškom, u Republici Sloveniji, tokom 1991–2015 godine. Na sve tri lokacije, faktorska opterećenja dva faktora pokazuju da je: 1) specifična aktivnost berilijuma-7 obuhvaćena faktorom 1 sa temperaturom, oblačnošću i relativnom vlažnošću; dok je 2) specifična aktivnost olova-210 obuhvaćena faktorom 2 sa količinom padavina i atmosferskim pritiskom. Iako je komunalitet već dva faktora veći od 0,5 za većinu posmatranih varijabli, tek uvođenjem trećeg faktora komunalitet za specifičnu aktivnost olova-210 i atmosferskog pritiska na sve tri merne lokacije raste na preko 0,5. Rezultati faktorske analize pokazuju da se specifične aktivnosti berilijuma-7 i olova-210 u prizmenom sloju atmosfere nalaze pod različitim dominantnim uticajima. Koncentracija berilijuma-7 je pod uticajem faktora regionalnog karaktera, koji je takođe dominantan za srednju temperaturu. Ova veza specifične aktivnosti berilijuma-7 i temperature preko dominantnog zajedničkog faktora važi i kada se broj faktora u analizi poveća na tri i četiri. Sa druge strane, na koncentraciju olova-210, kao i na količinu padavina i atmosferski pritisak, više uticaja ima lokalni faktor. Ova povezanost olova-210 sa druga dva meteorološka parametra, međutim, prestaje da važi sa povećanjem broja faktora u analizi na tri, kada se izdvaja specifičan faktor koji objašnjava preko 80% varijanse specifične aktivnosti olova-210. An association between the beryllium-7 and lead-210 specific activities in surface air and meteorological parameters is investigated using factor analysis. The measurements were conducted in Belgrade, Republic of Serbia, and Ljubljana and Krško, Republic of Slovenia, over 1991–2015. In all the locations, the factor loadings of two factors show that: 1) the beryllium-7 specific activity is encompassed by factor 1 together with temperature, cloud cover and relative humidity; while 2) the lead-210 specific activity, precipitation and atmospheric pressure are described by factor 2. Although the communalities of only two factors are already larger than 0.5 for most of the variables, an introduction of a third factor raises the communalities of all the variables above 0.5. The results imply that the beryllium-7 and lead-210 are under different dominant underlying mechanisms. The concentration of beryllium-7 seems to be primarily influenced by a mechanism of a regional character which is also a predominant factor for temperature. This association between the beryllium-7 specific activity and temperature prevails even when the number of factors in the analysis is raised to three and four. The lead-210 specific activity, on the other hand, together with precipitation and atmospheric pressure, is under an influence of a local mechanism, but that relationship between the variables ceases to hold when the number of factors is raised to three, and more than 80% of the variance in the Pb-210 specific activity is explained by one specific factor. Article is part of: [http://vinar.vin.bg.ac.rs/handle/123456789/8245]
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- 2017
29. Seasonality of 7 Be concentrations in Europe and influence of tropopause height
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Hernández-Ceballos, Miguel A., Brattich, Erika, Cinelli, Giorgia, Ajtić, Jelena, and Đurđević, Vladimir
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Europe ,seasonality ,tropopause height ,Be-7 ,transport time ,radiotracers - Abstract
This study aims at analysing the latitudinal variability of both the yearly and seasonal pattern of Be-7 surface activity concentrations, at addressing the impact of tropopause height (TPH) on Be-7 distribution and at evaluating the time lag between TPH and Be-7 at European level. With this aim, weekly Be-7 and daily TPH data at 17 sampling stations during 10 yr (2001-2010) are analysed. Be-7 shows a clear increasing tendency in the period and generally tends to increase with decreasing latitude. The seasonal pattern generally shows maxima during the warm period and minima during the cold one. The seasonal variogram analysis points out a good spatial correlation for TPH data while a weaker one is observed for Be-7, having TPH a larger influence on Be-7 during summer. The influence of TPH on Be-7 exhibits a large spatial variability, with a clear gap between south and north in the area of the polar front jet. The results identify the presence of two main groups, in particular separating between stations located in northern Europe (50 degrees N and higher) and stations in southern Europe (south of 50 degrees N). A similar behaviour for stations located in the same geographical area is also observed when looking at the day of maximum impact of TPH on Be-7 concentrations. The results suggest that Be-7 concentrations respond in different time ranges to changes in the TPH, observing seasonal differences in each group. These results represent the first European approach to the understanding of the TPH impact on Be-7 concentrations at surface levels.
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- 2016
30. Objektivna klasifikacija atmosferske cirkulacije iznad Srbije
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Tošić, Ivana, Unkašević, Miroslava, Ruml, Mirjana, Đurđević, Vladimir, Putniković, Suzana M., Tošić, Ivana, Unkašević, Miroslava, Ruml, Mirjana, Đurđević, Vladimir, and Putniković, Suzana M.
- Abstract
Vreme i klima neke oblasti odraz su na prvom mestu osobenosti opšte cirkulacije atmosfere. Promene u atmosferskoj cirkulaciji su presudne zato što su one često praćene promenama u površinskim meteorološkim promenljivama. Da bi se lakše proučavala veza između atmosferske cirkulacije i lokalnih vremenskih uslova, vrši se klasifikacija sinoptičkih sistema, tj. određuju se tipovi cirkulacije. Zato je glavni cilj ove disertacije da se na objektivan način identifikuju i opišu tipovi cirkulacije koji karakterišu vremenska stanja iznad Srbije. Proučavanje tipova cirkulacije je aktuelna tema, koja se stalno unapređuje i dopunjuje. Metod Jekinson-a i Collison-a je objektivna verzija Lamb-ove klasifikacije atmosferske cirkulacije, gde je dnevna cirkulacija okarakterisana upotrebom indeksa povezanih sa pravcem, jačinom i vrtložnošću strujanja. Ovaj metod je bio primenjen iznad Srbije za period od 1961. do 2010. Dobijeno je dvadesetšest cirkulacionih tipova: osam usmerenih tipova po pravcu − severni (N), severoistočni (NE), istočni (E), jugoistočni (SE), južni (S), jugozapadni (SW), zapadni (W) i severozapadni (NW), zatim dva vrtložna tipa zasnovana na jačini vrtložnosti − ciklonalni (C) i anticiklonalni (A) i šesnaest hibridnih tipova (osam ciklonalnih i osam anticiklonalnih za svaki pravac). Sinoptičke karakteristike dobijenih tipova su razmatrane za sve četiri sezone. Svaki cirkulacioni tip ima poseban sinoptički obrazac koji daje očekivan tip i smer strujanja iznad posmatrane oblasti. Analizirani su i trendovi i relativne učestalosti cirkulacionih tipova. Mana metoda Jekinson–a i Collison–a je što nema podataka na višim nivoima. Ovaj nedostatak je rešen u disertaciji tako što su analizirane anomalije geopotencijalne visine na 500 hPa. Utvrđeno je da je anticiklonalni (A) cirkulacioni tip najučestaliji u jesen (23,87%), zatim zimi (18,93%) i u leto (18,70%). Sledi severoistočni tip (NE) sa čestinom od 16,65% za vreme letnje sezone. A tip ima pozitivan trend za zimu i proleće, One of the primary dynamic factors shaping weather and climate of an area is the atmospheric circulation. Regional or local changes in meteorological parameters in the mid-latitudes are mainly controlled by the atmospheric circulation. In order to study relationships between atmospheric circulation and local weather conditions, classification of the synoptic systems is conducted, i.e., circulation weather types (WTs) are determined. Therefore, the main goal of this thesis is to objectively determine and explain the circulation weather types over Serbia. Studying of circulation types is a current topic that is constantly improved and updated. The method of Jenkinson and Collison is an objective version of the Lamb’s classification of atmospheric circulation, in which daily circulation is characterized using a set of indices associated with the direction, strength and vorticity of the flow. This method has been applied to the atmosphere over Serbia for the time period 1961- 2010, resulting in 26 WTs: eight pure directional types - northerly (N), northeasterly (NE), easterly (E), southeasterly (SE), southerly (S), southwesterly (SW), westerly (W) and northwesterly (NW), two pure types based on the severity of the vorticity - cyclonic (C) and anticyclonic (A), and sixteen hybrid types (eight cyclonic and eight anticyclonic for each direction). Synoptic characteristics of circulation types against all four seasonal times are considered. Each of the circulation types has a distinct underlying synoptic pattern that produces the expected type and direction of flow over the study area. Trends and relative frequencies of the circulation types are analyzed. A shortcoming of this method is the lack of data on other higher levels. In thesis, this deficiency has been solved by the vertical structure of the atmosphere that was employed to analyze the anomalies of the geopotential height at the 500 hPa. It has been found that the anticyclonic type (A), is the most common type of ci
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- 2017
31. Beryllium-7 surface concentration extremes in Europe
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Ajtić, Jelena, Sarvan, Darko, Đurđević, Vladimir S., Hernández-Ceballos, Miguel A., Brattich, Erika, Ajtić, Jelena, Sarvan, Darko, Đurđević, Vladimir S., Hernández-Ceballos, Miguel A., and Brattich, Erika
- Abstract
Seasonal and spatial patterns of extremely high beryllium-7 surface concentration recorded over the 2001-2010 period across Europe are investigated. The beryllium-7 measurements for 14 sites are taken from the Radioactivity Environmental Monitoring Database. The maxima and minima in the annual cycle of the beryllium-7 surface concentration occur later in the year as the latitude of the measurement site decreases. Extremely high beryllium-7 surface concentrations are defined here as values greater than the 95th percentile in each measurement site. Most of the extremes occur over the March-August period. At least 10 % of the total number of extremes appear during autumn and winter, with an exception of Vienna, where all the extremes took place during spring and summer. The regional spread of extremes common to pairs of measurement sites points to an existence of three distinct regions in Europe: north of 55°N, between 45°N and 55°N, and south of 45°N. Although the beryllium-7 concentration records are significantly correlated across all the investigated sites, the strongest correlations are found within the identified regions., Sezonska i prostorna raspodela ekstremno visokih specifičnih aktivnosti berilijuma-7 u prizemnom sloju atmosfere analizirane su u ovom radu. Merenja tokom 2001-2010. godine na 14 evropskih stanica preuzeta su iz REMdb-baze podataka Monitoring radioaktivnosti u životnoj sredini. Prvo su razmotreni godišnji ciklusi specifične aktivnosti berilijuma-7 koji pokazuju da se godišnje maksimalne i minimalne srednje mesečne vrednosti pomeraju ka kasnijim mesecima kako se smanjuje geografska širina merne stanice. Za ekstremno visoke vrednosti specifične aktivnosti berilijuma-7 uzete su vrednosti veće od 95-og percentila, koji je izračunat za svaku stanicu posebno. Najveći broj ovih ekstrema događa se od marta do avgusta, a najmanje 10 % od ukupnog broja ekstrema tokom jeseni i zime. Izuzetak je merna stanica Beč na kojoj su se svi ekstremi dogodili tokom proleća i leta. Rasprostranjenost ekstrema koji su zajednički za parove mernih mesta, ukazuje da postoje tri različita regiona u Evropi: severno od 55°N, između 45°N i 55°N, i južno od 45°N. Iako su merenja specifične aktivnosti berilijuma-7 značajno korelisana za sve analizirane stanice, najveći koeficijenti korelacije dobijeni su u okviru ovih regiona.
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- 2017
32. Dynamics of beryllium-7 specific activity in relation to meteorological variables, tropopause height, teleconnection indices and sunspot number
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Sarvan, Darko, Sarvan, Darko, Stratimirović, Đorđe, Blesić, Suzana, Đurđević, Vladimir, Miljković, Vladimir, Ajtić, Jelena, Sarvan, Darko, Sarvan, Darko, Stratimirović, Đorđe, Blesić, Suzana, Đurđević, Vladimir, Miljković, Vladimir, and Ajtić, Jelena
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The dynamics of the beryllium-7 specific activity in surface air over 1987-2011 is analyzed using wavelet transform (WT) analysis and time -dependent detrended moving average (tdDMA) method, WT analysis gives four periodicities in the beryllium-7 specific activity: one month, three months, one year, and three years. These intervals are further used in tdDMA to calculate local autocorrelation exponents for precipitation, tropopause height and teleconnection indices. Our results show that these parameters share common periods with the beryllium-7 surface concentration. tdDMA method indicates that on the characteristic intervals of one year and shorter, the beryllium-7 specific activity is strongly autocorrelated. On the three-year interval, the beryllium-7 specific activity shows periods of anticorrelat ion, implying slow changes in its dynamics that become evident only over a prolonged period of time. A comparison of the Hurst exponents of all the variables on the one- and three-year intervals suggest some similarities in their dynamics. Overall, a good agreement in the behavior of the teleconnection indices and specific activity of beryllium-7 in surface air is noted.
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- 2017
33. Simulation of long-term changes in environmental factors and grassland composition in three protected areas of Serbia
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Čavlović, Dragana, Beloica, Jelena, Obratov-Petković, Dragica, Đurđević, Vladimir, Košanin, Olivera, Čavlović, Dragana, Beloica, Jelena, Obratov-Petković, Dragica, Đurđević, Vladimir, and Košanin, Olivera
- Abstract
Intense direct and indirect human pressure has been imposed on grasslands throughout their range. Mostly due to the constant need for more food production or due to changes in environmental conditions, grasslands as habitats are expected to become highly endangered. The aim of this study was to estimate the grasslands’ ecological response to future climate and environmental changes. The study took place in three ecologically different grassland communities in three protected natural areas of Serbia (Southeastern Europe), following the same methodology. The study sites were: 1) Peštersko polje Special Nature Reserve (SNR), 2) Deliblato sands SNR (its southern part: Labudovo okno) and 3) Zasavica SNR. Climate change was simulated for mean temperatures and precipitations using the Eta Belgrade University-Princeton Ocean Model (EBU-POM) climate model, for the A1B Intergovernmental Panel on Climate Change (IPCC) emission scenario covering the 1951–2100 period and insolation and volumetric soil moisture content for the 1979–2100 period. Grassland vegetation was analysed at all three sites. One representative plant community per site was selected for further analysis and simulation of ecological changes. One plot was positioned inside each of the above-mentioned communities, all vascular plant species inside the plot were recorded, and soil samples were taken. Ecological Optima (EO) for moisture and temperature were calculated from modified Ellenberg’s plant indicator values of recorded species. The plants’ response to climate and environmental changes was simulated using the VSD+ model for the 2010–2100 period. The data obtained from the model were further analysed with Canonical Correspondence Analysis (CCA). Overall results show that the temperature rise, along with the irregular precipitation at all three sites, will lead to a drop of the relative abundance of many native species in the period between 2040 and 2060. The low obtained Habitat Suitability Index for the fu, In Serbien sind vor allem natürliche Grasländer stark gefährdet. Bislang liegen nur sehr wenige Studien zur Auswirkung von Klimaveränderungen auf Grasländer in Serbien vor (z. B. BELOICA et al. 2015). Zudem wurde die Biodiversität des Graslands in Südosteuropa bislang insgesamt kaum untersucht (DENGLER et al. 2014). Das Ziel dieser Studie ist ein Beitrag zur Kenntnis, inwieweit Pflanzengesellschaften auf veränderte Klimabedingungen reagieren. Die Untersuchung wurden in drei Schutzgebieten in Serbien durchgeführt; untersucht wurden drei ökologisch verschiedene Graslandgesellschaften. Die drei Untersuchungsgebiete waren das Peštersko polje-Special Nature Reserve (SNR), das Delibater Sande-SNR (dessen südlicher Teil zum Gebiet Labudovo okno gehört) und das Zasavica-SNR. Zunächst wurde die Graslandvegetation der drei Gebiete analysiert. In jedem Gebiet wurde eine repräsentative Pflanzengesellschaft ausgewählt um die ökologischen Veränderungen zu simulieren. Die ökologischen Optima der Arten hinsichtlich Feuchte und Temperatur wurden auf Grundlage von Zeigerwerten (nach KOJIĆ et al. 1997) berechnet. Die Bodeneigenschaften wurden an den gleichen Orten bestimmt, wo die Aufnahmen erstellt wurden. Die Namen der Pflanzenarten entsprechen der EURO+MED-Datenbank und die Habitattypen EUNIS. Die Veränderungen der mittleren Temperatur und des mittleren Niederschlags nach dem A1B-(IPCC 2014)-Szenario wurden auf Grundlage des Zeitraums 1951–2100 mit Hilfe von EBUPOM-Klimamodellen simuliert. Die Einstrahlung und der volumetrische Bodenwassergehalt wurden auf Grundlage des Zeitraums 1979–2100 simuliert. Die Reaktion der Pflanzen auf die Klima- und Umweltveränderungen wurde mit Hilfe von VSD+ (Version 5.5, 2001, 2015 Alterra, CCE; MOLDIJKSTRA & REINDS 2017) für den Zeitraum 2010–2100 simuliert. Eine kanonische Korrespondenzanalyse der Pflanzengesellschaften für denselben Zeitraum wurde mit Hilfe von Past 3.14 (HAMMER et al. 2001) durchgeführt.
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- 2017
34. Suše i proces aridizacije kao faktor degradacije zemljišta na području Deliblatske peščare
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Кадовић, Ратко, Đurđević, Vladimir, Костадинов, Станимир, Knežević, Milan, Белановић-Симић, Снежана, Mansour, Yousef Ali Bohajar, Кадовић, Ратко, Đurđević, Vladimir, Костадинов, Станимир, Knežević, Milan, Белановић-Симић, Снежана, and Mansour, Yousef Ali Bohajar
- Abstract
In this doctoral dissertation, the research of the influences of droughts and the process of aridification have been conducted on Deliblato Sands area’s sensitivity, as a Special nature reserve, especially from the aspect of land degradation, the condition of vegetation cover and sustainable management of these ecosystems. Research included two groups: climatological studies (for the period 1980-2010) and the studies of soil. Within climatological studies, the focus was on climate factors most often used in the research of land degradation. This primarily refers to precipitation (P), temperature (T), wind (W) and their extremes, potential evapotranspiration (PET), standardized precipitation index (SPI for 1. 2. 3. 6 and 12 monts ) and aridity indices (AI and BGI). Soil studies (31 pedological profiles) comprised of field and laboratory research that defined morphological, physical and chemical properties. Based on these researches, described and selected soils were grouped into four categories, according to WRB classification: group I – Protic Arenosol (Calcaric), group II – Arenosol (Haplic, Calcaric), group III – Chernozem (Arenic), group IV – Glaysol (Calcaric, Arenic). The results of soil degradation of Deliblato Sands, amongst other, have enabled the marking off of three texture classes which belong to different categories of erodibility: highly erodible soils with 56.17% (sand), medium erodible soils with 41.27% (clay sand) and low erodible soils with 36.62% (sandy clay). Soil sensitivity to the process of wind erosion, in model RWEQ, is defined by the participation of erodible fraction (EF) that contains soil particles <0.84 mm. The erodible fraction depends on physical and chemical soil properties, including the contents of sand, dust and clay, the contents of organic matter and CaCO3 in surface level 0-25 mm. Using the same model, the soil crust factor (SCF) is determined which reflects the changes of abrasive surface resistance, when the surface is modifie
- Published
- 2016
35. Beryllium-7 specific activity in surface air and its correlation with meteorological variables, solar zenith angle, and number of sunspots
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Ajtić, Jelena, Đurđević, Vladimir, Sarvan, Darko, Brattich, Erika, Hernandez-Ceballos, Miguel A., Ajtić, Jelena, Đurđević, Vladimir, Sarvan, Darko, Brattich, Erika, and Hernandez-Ceballos, Miguel A.
- Abstract
This analysis presents linear correlations of beryllium-7 specific activity in surface air with several variables measured in Helsinki, Finland, over 1987-2011. Measurements of beryllium-7 are linearly correlated with the following 10 variables: tropopause height; mean, minimum and maximum temperature; precipitation; atmospheric pressure; potential vorticity at 300 hPa and 200 hPa; solar zenith angle; and the number of sunspots. A time lag is also introduced into the calculations of Pearsons linear correlation coefficients, i.e. the beryllium-7 specific activity measured on a day is correlated with a value of a given variable measured on some preceding day. In particular, the time lag is allowed to vary between 0 and 7 days for tropopause height, meteorological parameters and potential vorticity, and between 0 and 31 days for solar zenith angle and number of sunspots. In this way, we obtain sets of correlation coefficients for each pair of the analysed variables, in which we look for the maximum correlation coefficient as well as for the time lag on which this value is reached. In addition to investigating all of the available measurements, the time series are further split into seasonal subsets. Weak to moderate maximum correlation coefficients, ranging between 0.29 and 0.44, are found for the beryllium-7 specific activity with the tropopause height, temperatures and atmospheric pressure. These correlations are reached with a time lag of 0-2 days. Seasonal correlation coefficients show that the strongest linear relationships are obtained in summer. Similarly, a moderate correlation (0.48) with the solar zenith angle is reached with a time lag of 0 days, but the seasonal correlation coefficients in this case show a weaker relationship during different seasons. On the other hand, our analysis suggests that the correlations of beryllium-7 with precipitation, potential vorticity and the number of sunspots are not statistically significant.
- Published
- 2016
36. The Fourier analysis applied to the relationship between Be-7 activity in the Serbian atmosphere and meteorological parameters
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Rajačić, Milica, Todorović, Dragana, Krneta-Nikolić, Jelena D., Janković, Marija M., Đurđević, Vladimir S., Rajačić, Milica, Todorović, Dragana, Krneta-Nikolić, Jelena D., Janković, Marija M., and Đurđević, Vladimir S.
- Abstract
Air sample monitoring in Serbia, Belgrade started in the 1960s, while Be-7 activity in air and total (dry and wet) deposition has been monitored for the last 22 years by the Environment and Radiation Protection Department of the Institute for Nuclear Sciences, Vinca. Using this data collection, the changes of the Be-7 activity in the air and the total (wet and dry) deposition samples, as well as their correlation with meteorological parameters (temperature, pressure, cloudiness, sunshine duration, precipitation and humidity) that affect Be-7 concentration in the atmosphere, were mathematically described using the Fourier analysis. Fourier analysis confirmed the expected; the frequency with the largest intensity in the harmonic spectra of the Be-7 activity corresponds to a period of 1 year, the same as the largest intensity frequency in Fourier series of meteorological parameters. To analyze the quality of the results produced by the Fourier analysis, we compared the measured values of the parameters with the values calculated according to the Fourier series. Absolute deviations between measured and predicted mean monthly values are in range from 0.02 mBq/m(3) to 0.7 mBq/m(3) for Be-7 activity in air, and 0.01 Bq/m(2) and 0.6 Bq/m(2) for Be-7 activity in deposition samples. Relatively good agreement of measured and predicted results offers the possibility of prediction of the Be-7 activity. (C) 2016 Elsevier Ltd. All rights reserved.
- Published
- 2016
37. Modeliranje hidrološkog ciklusa u integrisanom geofizičkom sistemu
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Rajković, Borivoj, Đurđević, Vladimir, Vuković, Ana, Vujadinović Mandić, Mirjam P., Rajković, Borivoj, Đurđević, Vladimir, Vuković, Ana, and Vujadinović Mandić, Mirjam P.
- Abstract
Hidrološki ciklus u integrisanom geofizičkom sistemu ima ulogu da simulira procese vezane za kopnene vode i međusobne interakcije komponenti klimatskog sistema koji opisuju kruženje vode u prirodi. Numerički modeli za prognozu vremena i simulaciju klime obuhvataju najveći deo ovih procesa i razvojem računarskih resursa postaju kompleksniji i prerastaju u modele za simulaciju celog geofizičkog sistema. Hidrološki ciklus u operativnim modelima nije zatvoren zbog nedostatka dinamičkog modela koji simulira kopneni oticaj vode. U ovom radu je predstavljen numerički model za simulaciju i prognozu površinskog oticaja koji direktno utiče na stanje podloge, što je donji granični uslov za atmosferske procese i prognozu vremena. Model je razvijen u skladu sa modelom za prognozu vremena poslednje generacije, NMMB, koji ima sposobnost da simulira procese od globalnih do lokalnih razmera. Testiranje numeričke ispravnosti nove komponente hidrološkog ciklusa kvalifikovalo ga je za povezivanje sa atmosferskim modelom. Povezani numerički model sa zatvorenim hidrološkim ciklusom otvara mogućnost za poboljšanje kvaliteta prognoza i klimatskih simulacija i uvodi nove prognostičke produkte koji mogu naći upotrebu u sistemima najava i upozorenja na ekstremne vremenske prilike. Upotreba ovakvog modela u operativnoj prognozi demonstrirana je na primeru simulacije majskih poplava 2014. godine u oblasti zapadnog Balkana. Povezani model je uspešno reprodukovao hidrološki ciklus ove vremenske nepogode, tj. intenzivne padavine, njihovo oticanje po površini i akumulaciju, uključujući njegovu interakciju sa podlogom i atmosferom, sve do porasta signala u rečnom toku, u skladu sa osmatranjim, Hydrological cycle in the integrated geophysical system simulates processes related to inland waters and interactions between the climate system components, that describes water cycle in its natural environment. Numerical models for weather forecast and climate simulations include majority of these processes and, following computer resource development, they are more complex and evolve into models of the integrated geophysical system. Hydrological cycle in operational numerical weather prediction models is not complete because dynamical overland water flow component is missing. Here is presented numerical model for simulation and forecast of the surface runoff, which has direct impact on land surface conditions and thereby lower boundary condition for atmospheric processes and weather forecast as well. The model is developed following numerical approach in the last generation weather forecast model, NMMB, which has the ability to simulate processes from global to local scales. Tests for numerical stability of the new hydrological cycle component justified its implementation within the atmospheric model. Coupled numerical model with complete water cycle opens new possibilities for quality increase in weather forecast and climate simulation, and introduces new prognostic products, which can be used in extreme weather warning system. Such model performance in operational forecast is demonstrated in case study of May 2014 flood event over west Balkans. Coupled model successfully simulated hydrological cycle in this extreme weather event with high precipitation, intense water surface runoff and accumulation, including its interaction with land surface and atmosphere, and at the end producing high signal in river discharge as observed.
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- 2015
38. Predictability of lead-210 in surface air based on multivariate analysis
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Ajtić, Jelena, Ajtić, Jelena, Maletić, Dimitrije, Stratimirović, Đorđe, Blesić, Suzana, Nikolić, Jelena, Đurđević, Vladimir, Todorović, Dragana, Ajtić, Jelena, Ajtić, Jelena, Maletić, Dimitrije, Stratimirović, Đorđe, Blesić, Suzana, Nikolić, Jelena, Đurđević, Vladimir, and Todorović, Dragana
- Abstract
Dependence of the lead-210 activity concentration in surface air on meteorological variables and teleconnection indices is investigated using multivariate analysis, which gives the Boosted Decision Trees method as the most suitable for variable analysis. A mapped functional behaviour of the lead-210 activity concentration is further obtained, and used to test predictability of lead-210 in surface air. The results show an agreement between the predicted and measured values. The temporal evolution of the measured activities is satisfactorily matched by the prediction. The largest qualitative differences are obtained for winter months.
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- 2015
39. Climate change effects and UV-B radiation in the Vojvodina region, Serbia under the SRES-A2
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Malinović-Milićević, Slavica B., Malinović-Milićević, Slavica B., Mihailović, Dragutin T., Drešković, Nusret M., Đurđević, Vladimir S., Mimić, Gordan I., Arsenić, Ilija D., Malinović-Milićević, Slavica B., Malinović-Milićević, Slavica B., Mihailović, Dragutin T., Drešković, Nusret M., Đurđević, Vladimir S., Mimić, Gordan I., and Arsenić, Ilija D.
- Abstract
In this article we considered the extreme temperatures, precipitation and UV-B radiation in Vojvodina region, Serbia. We describe the actual climate conditions for the period 1981-2007 and applied a dynamic downscaling technique using the EBU-POM regional coupled climate model under the SRES-A2 scenario to assess the changes for the period 2021-2100. The results indicate that a warmer and drier climate in the Vojvodina region can be expected at the end of the century. Projection of climate indicates to a strong increase in the mean annual minimum temperatures, and much smaller increase in the mean annual maximum temperatures. The increase of both extreme temperatures is predicted to be the highest in the winter and the lowest in the summer. Mean annual precipitation is projected to increase toward the end of the first half of the 21st century and to decrease for the last 30 years of the 21st century. Precipitation amount will be the highest during the winter and spring. The model simulations show that, by the end of this century, annual mean UV-B dose will recover by 5.2%. Recovery will be faster in the first half of the 21st century and more slowly later on. The UV-B doses recovery is expected to be the highest during the autumn and spring.
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- 2015
40. Kant via Adorno, sa Hegelom u zaleđu
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Krstić, Predrag, Kinđić, Zoran, Đurđević, Vladimir, Krstić, Predrag, Krstić, Predrag, Kinđić, Zoran, Đurđević, Vladimir, and Krstić, Predrag
- Published
- 2014
41. Effects of glutathione S-transferase T1 and M1 deletions on advanced carotid atherosclerosis, oxidative, lipid and inflammatory parameters
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Živković, Maja, Stanković, Aleksandra, Đurić, Tamara, Končar, Igor, Kolaković, Ana, Đurđević, Vladimir, Davidović, Lazar, Alavantić, Dragan, Živković, Maja, Stanković, Aleksandra, Đurić, Tamara, Končar, Igor, Kolaković, Ana, Đurđević, Vladimir, Davidović, Lazar, and Alavantić, Dragan
- Abstract
Glutathione S-transferases (GSTs) carry out a wide range of functions in cells, such as detoxification of endogenous compounds, removal of reactive oxygen species, and even catalysis of reactions in metabolic pathways beyond detoxification. Based on previous research, GSTM1 and GSTT1 might modify the risk of atherosclerosis. The aim of our study was to analyze the possible association of GSTM1 and GSTT1 gene polymorphisms with the occurrence of carotid plaque (CP); and biochemical parameters of oxidative stress, lipid profile and inflammation, in 346 consecutive patients with advanced atherosclerosis that underwent endarterectomy. A multiplex polymerase chain reaction (PCR) method was used to detect the deletions in GSTM1 and GSTT1 genes in the genomic DNA in 346 patients and 330 controls. The adjusted OR for CP presence (adjusted for age, gender, smoking, hypertension, BMI, HDLC, TG) was 0.24, 95 %CI 0.08-0.7, p LT 0.01 for GSTT1 null and 1.13, 95 %CI 0.62-2.07, p = 0.7 for GSTM1 null genotype. We found significantly lower plasma lipoprotein (a) (Lp(a)) levels in GSTT1 null compared to wild-type genotype carriers in patient group (20.68 +/- A 26.02 mg/dl vs. 40.66 +/- A 42.89 mg/dl, mean +/- A SD, p = 0.04). The serum interleukin-6 (IL-6) values were significantly influenced by both GST polymorphisms in patients with CP. Our results, showing the significant reduction of GSTT1 deletions in patients with CP, suggest involvement of GSTs in carotid atherosclerosis. This study shows additional view of the possible role of GSTs in advanced chronic inflammatory disease of vascular system, but the confirmation in a larger studies in different populations are needed.
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- 2014
42. Wavelet spectral analysis of teleconnection indices and activities of beryllium-7 and lead-210 in ground level air in Belgrade, Serbia
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Ajtić, Jelena, Ajtić, Jelena, Stratimirović, Đorđe, Đurđević, Vladimir, Todorović, D., Nikolić, J., Ajtić, Jelena, Ajtić, Jelena, Stratimirović, Đorđe, Đurđević, Vladimir, Todorović, D., and Nikolić, J.
- Abstract
Activities of beryllium-7 and lead-210 are monitored in ground level air in Belgrade, Serbia. The measuring sites are located at the Institute of Nuclear Sciences Vinča. The activities are determined on HPGe detectors by standard gamma spectrometry. Five teleconnection indices of large scale atmospheric circulation: North Atlantic Oscillation, East Atlantic Pattern, East Atlantic/West Russia Pattern, Scandinavia Pattern, and Polar/Eurasia Pattern are obtained from the data archive of the United States National Oceanic and Atmospheric Administration's Climate Prediction Center. The collected time series consist of monthly values and span more than two decades: beryllium-7 since 1991, lead-210 since 1985, and the teleconnection indices since 1950, thus offering data arrays of sufficient lengths for wavelet spectral analysis. A relation between the radionuclides' activities and the indices is first investigated using Pearson's correlation coefficients. The computed coefficients do not indicate a linear relationship between the variables. However, the wavelet spectral analysis shows a number of common characteristic frequencies in the data arrays. The annual cycle of all the variables is clearly evident. A common time period of two to three years is also found, as well as a higher frequency variability corresponding to five to six months.
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- 2014
43. Kant via Adorno, sa Hegelom u zaleđu
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Kinđić, Zoran, Đurđević, Vladimir, Krstić, Predrag, Kinđić, Zoran, Đurđević, Vladimir, and Krstić, Predrag
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- 2014
44. A multi-year study of radioactivity in surface air and its relation to climate variables in Belgrade, Serbia
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Ajtić, Jelena, Todorović, Dragana, Nikolić, Jelena D., Đurđević, Vladimir S., Ajtić, Jelena, Todorović, Dragana, Nikolić, Jelena D., and Đurđević, Vladimir S.
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Activities of 7Be and 210Pb were monitored in surface air in Belgrade, Serbia, from 2004 to 2012. The measurements were taken from two locations, in an open field of a city suburb and in the central city area. The activities were determined on HPGe detectors by standard gamma spectrometry. The 7Be activity shows a pronounced seasonal pattern, with the maximum in spring-summer and minimum in winter, while the 210Pb activity exhibits two maxima, in autumn and late winter. The mean monthly concentrations measured at both sites are below 9 mBq/m3 and 1.3 mBq/m3 for 7Be and 210Pb, respectively. The obtained correlation of the 7Be activity with the number of sun-spots is not statistically significant. Relations of the radionuclides' activities with climate variables (precipitation, temperature, relative humidity, cloud cover, sunshine hours, and atmospheric pressure) are also investigated, but the only significant correlations are found for the 7Be activity with temperature and sunshine hours, and the 210Pb activity with atmospheric pressure. The maximum 7Be and 210Pb activities corresponding to binned total monthly precipitation data imply different modes of the radionuclide scavenging from the atmosphere. During dry periods, accumulation of the radionuclides in the atmosphere leads to their increased activities, but no correlation was found between the activities and the number of consecutive dry days., Aktivnosti 7Be i 210Pb merene su tokom 2004-2012, u prizemnom sloju atmosfere na dve lokacije u Beogradu. Mesečne specifične aktivnosti određene su standardnom metodom spektrometrije gama zračenja na HPGe detektorima. Aktivnosti radionuklida pokazuju sezonski karakter: 7Be ima maksimum tokom proleća i leta, a minimum zimi, dok 210Pb ima dva maksimuma, tokom jeseni i kasne zime. Na obe lokacije, srednje mesečne aktivnosti 7Be su manje od 9 mBq/m3, dok su za 210Pb manje od 1.3 mBq/m3. Između aktivnosti 7Be i broja sunčevih pega nije nađena statistički značajna korelacija. Relacije između aktivnosti ovih radionuklida i klimatskih parametara (količina padavina, temperatura, relativna vlažnost, oblačnost, broj sunčanih sati i atmosferski pritisak) takođe su ispitane, ali su značajne korelacije dobijene samo za aktivnost 7Be sa temperaturom i brojem sunčanih sati, odnosno za aktivnost 210Pb sa atmosferskim pritiskom. Na osnovu veze između maksimalne aktivnosti po intervalima količine padavina, mogu se razlikovati tri režima spiranja radionuklida iz atmosfere. Tokom sušnih perioda, akumulacija radionuklida u atmosferi uzrokuje njihovu povišenu aktivnost, ali korelacija između aktivnosti i broja uzastopnih suvih dana nije dobijena.
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- 2013
45. A Multi-Year Study of Radioactivity in Surface Air and Its Relation to Climate Variables in Belgrade, Serbia
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Ajtić, Jelena V., Todorović, Dragana, Krneta-Nikolić, Jelena D., Đurđević, Vladimir S., Ajtić, Jelena V., Todorović, Dragana, Krneta-Nikolić, Jelena D., and Đurđević, Vladimir S.
- Abstract
Activities of Be-7 and Pb-210 were monitored in surface air in Belgrade, Serbia, from 2004 to 2012. The measurements were taken from two locations, in an open field of a city suburb and in the central city area. The activities were determined on HPGe detectors by standard gamma spectrometry. The Be-7 activity shows a pronounced seasonal pattern, with the maximum in spring-summer and minimum in winter, while the Pb-210 activity exhibits two maxima, in autumn and late winter. The mean monthly concentrations measured at both sites are below 9 mBq/m(3) and 1.3 mBq/m(3) for Be-7 and Pb-210, respectively. The obtained correlation of the Be-7 activity with the number of sun-spots is not statistically significant. Relations of the radionuclides activities with climate variables (precipitation, temperature, relative humidity, cloud cover, sunshine hours, and atmospheric pressure) are also investigated, but the only significant correlations are found for the Be-7 activity with temperature and sunshine hours, and the Pb-210 activity with atmospheric pressure. The maximum Be-7 and Pb-210 activities corresponding to binned total monthly precipitation data imply different modes of the radionuclide scavenging from the atmosphere. During dry periods, accumulation of the radionuclides in the atmosphere leads to their increased activities, but no correlation was found between the activities and the number of consecutive dry days.
- Published
- 2013
46. Wavelet spectral analysis of teleconnection indices and activities of beryllium-7 and lead-210 in ground level air in Belgrade, Serbia
- Author
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Ajtić, Jelena, Stratimirović, Đorđe, Đurđević, Vladimir, Todorović, D., and Nikolić, J.
- Subjects
Beryllium-7 ,Teleconnection indices ,Air ,Lead-210 ,Wavelet analysis - Abstract
Activities of beryllium-7 and lead-210 are monitored in ground level air in Belgrade, Serbia. The measuring sites are located at the Institute of Nuclear Sciences Vinča. The activities are determined on HPGe detectors by standard gamma spectrometry. Five teleconnection indices of large scale atmospheric circulation: North Atlantic Oscillation, East Atlantic Pattern, East Atlantic/West Russia Pattern, Scandinavia Pattern, and Polar/Eurasia Pattern are obtained from the data archive of the United States National Oceanic and Atmospheric Administration's Climate Prediction Center. The collected time series consist of monthly values and span more than two decades: beryllium-7 since 1991, lead-210 since 1985, and the teleconnection indices since 1950, thus offering data arrays of sufficient lengths for wavelet spectral analysis. A relation between the radionuclides' activities and the indices is first investigated using Pearson's correlation coefficients. The computed coefficients do not indicate a linear relationship between the variables. However, the wavelet spectral analysis shows a number of common characteristic frequencies in the data arrays. The annual cycle of all the variables is clearly evident. A common time period of two to three years is also found, as well as a higher frequency variability corresponding to five to six months.
47. Uticaj promene biosfere u Panonskom basenu na lokalnu i regionalnu klimu tokom prolećnih, letnjih i jesenjih meseci
- Author
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Ruman, Albert, Đurđević, Vladimir, Tošić, Ivana, and Vujadinović Mandić, Mirjam
- Subjects
atmospheric circulation, biosphere, temperature, radiation, Earth climate system, climate model MPI-ESM ,cirkulacija atmosfere, biosfera, temperatura, zračenje, klimatski sistem Zemlje, klimatski model MPI-ESM - Abstract
Uticaj kopnene vegetacije na fizičke procese u površinskom i planetarnom graničnom sloju atmosfere je od velikog značaja za izučavanje vremenskih i klimatskih uslova u klimatskom sistemu Zemlje. Kopnena vegetacija, kao sastavni deo klimatskog sistema Zemlje, ima veliki uticaj na razmenu energije između kopna i atmosfere, a usled toga i značajnu ulogu u definisanju vremenskih i klimatskih obrazaca, kako na globalnom, tako i na regionalnom i lokalnom nivou. Međutim, usled konstantnog antropogenog uticaja, ali i zbog sopstvene dinamike, ovaj vegetacioni sistem se stalno menja i veoma ga je komplikovano predstaviti, kao i njegov uticaj na klimatski sistem Zemlje. Cilj ovog istraživanja je proučavanje uticaja regionalne promene vegetacije na sezonsku temperaturu vazduha u blizini Zemljine površine. Istraživanje je urađeno upotrebom globalnog klimatskog modela MPI-ESM (Max Planck Institute - Earth System Model). Oblast ovog istraživanja je smeštena u Panonskom basenu koji predstavlja jedan od mnogih regiona u kome je antropogeni uticaj na geofizičke promene životne sredine veliki. Vremenski okvir unutar koga su rađeni numerički eksperimenti MPI-ESM modelom je pokrivao period od 2002. do 2011. godine. Izmena zastupljenosti tipova šumske, travnate i poljoprivredne vegetacije koja je izvedena u istraživanju nedvosmisleno pokazuje da je došlo do povećanja dekadnih vrednosti srednjih sezonskih temperatura vazduha u blizini Zemljine površine (T2m) i temperature vazduha u nižim slojevima atmosfere (Tlev), kako na lokalnom tako i na regionalnom nivou. Međutim, došlo je i do značajnih promena u trendovima srednjih sezonskih vrednosti: temperature vazduha u blizini Zemljine površine (YT2m), fluksa osetne toplote (YFh), fluksa latentne toplote (YFl), površinskog albeda (Ya) i oblačnosti (YOb). Postignut je trend hlađenja vazduha u letnjoj sezoni, dok je u prolećnoj postignut trend zagrevanja prizemnog vazduha, a za jesenju sezonu dobijeni su trendovi zagrevanja i hlađenja vazduha. Promena trenda YT2m je uglavnom dobijena usled promene u površinskom albedu, kao i usled promene oblačnosti. Trend hlađenja vazduha za letnju sezonu je zastupljen uglavnom u severnim i centralnim oblastima Panonskog basena dok je u južnoj oblasti zabeležen trend zagrevanja. Ovim istraživanjem je postignut postavljeni cilj, odnosno potvrđeno je da postoji značajan antropogeni uticaj na promenu klimatskih uslova, kako na lokalnom, tako i na regionalnom nivou, usled geofizičkih uticaja na kopnenu vegetaciju. Pokazalo se da izmenom vegetacije na površini možemo ublažiti zagrevanje u letnjoj sezoni, kao i da ubrzamo povećanje prizemne temperature vazduha u prolećnoj sezoni, dok je za jesenju sezonu postignuto i hlađenje i zagrevanje. The influence of terrestrial vegetation on developments in the surface and planetary boundary layer of the atmosphere has great importance for the study of weather and climatic conditions in the Earth's climate system. Terrestrial vegetation as an integral part of the Earth's climate system has a great influence on the exchange of energy between the land and the atmosphere and consequently a significant role in defining weather and climate patterns globally, regionally and locally. However, due to the constant anthropogenic impact, this vegetation system is constantly changing and it is very complicated to present it during research as well as its impact on the Earth's Climate System. The aim of this study is to study the impact of regional vegetation change on the seasonal air temperature near the Earth's surface and was performed using the global climate model MPI-ESM (Max Planck Institute - Earth System Model). The region of our research is located in the Pannonian basin and is one of many regions in which the anthropogenic impact on geophysical changes in the environment is great. The research was conducted for a ten-year period from 2002 to 2011. The change in the concentration of CF types that we performed in our study unequivocally shows that it has led to an increase in decadal values of mean seasonal air temperatures: near the Earth's surface (T2m) and air temperature in the lower atmosphere (Tlev) both locally and at the regional level. However, there were also significant changes in the trends of average seasonal values: air temperature near the Earth's surface (YT2m), sensory heat flux (YFh), latent heat flux (YFl), surface albedo (Ya), cloud cover (YOb) and soil water content (YSW). We managed to achieve the trend of air cooling in the summer season, while in the spring we got the trend of heating the ground air, and for the autumn season we got the trend of heating and cooling the air. The change in the YT2m trend was mainly due to a change in surface albedo as well as due to a change in cloud cover. The trend of air cooling that we received for the summer season is represented mainly in the northern and central areas of the Pannonian basin, while for the southern area we received a trend of warming. For the spring season, we mainly obtained a mean positive linear correlation between the mean monthly values of air temperature T2m and the mean monthly values of the sensory heat flux Fh. For the summer season we mostly got that medium and strong linear correlation while for the autumn season we got weak positive and weak negative linear correlation. Through our research, we have achieved the set goal and shown that there is a significant anthropogenic impact on climate change at both local and regional levels. We have shown that we can mitigate warming in the summer season as well as accelerate the increase in ground air temperature in the spring season while we have achieved both cooling and warming for the autumn season...
- Published
- 2022
48. Viability of European ground squirrel population (Spermophilus citellus) under climate and land use change
- Author
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Nikolić, Tijana, Milić, Dubravka, Ćirović, Duško, Bjelić-Čabrilo, Olivera, Marković, Vladimir, and Đurđević, Vladimir
- Subjects
species diversity ,promena klime ,mere zaštite ,ekološko modelovanje ,diverzitet vrsta ,habitat network ,open grassland areas ,mreža staništa ,otvorena travnata staništa ,agroecological zoning ,European ground squirrel ,sitni sisari ,climate change ,small mammals ,active conservation measures ,ecological modeling ,ekološko zoniranje ,Tekunica ,protected areas ,zaštićena područja - Abstract
U radu je analiziran odgovor lokalnih populacija tekunice u Vojvodini na promene uslova klime i korišćenja zemljišta. Odgovori populacija tekunice (tipičnog predstavnika otvorenih staništa i idealnog model organizma) na pomenute promene omogućiće razmatranje kako mere na regionalnom nivou: i) mogu unaprediti zaštitu i očuvanje tekunice ii) ublažiti efekti promene klime i korišćenja zemljišta iii) mogu usaglasiti razvoj poljoprivrede sa očuvanjem biodiverziteta travnatih ekosistema. Kako bi se odgovorilo na pitanja i postavljene hipoteze u radu sprovedeno je terensko istraživanje, korišćen standardni prostorni pristup i ekološko modelovanje. Sve primenjene tehnike su komplementarne jedna drugoj u dobijanju odgovora na postavljena pitanja gde rezultati jedne analize predstavljaju ulazne podatke za drugu analizu. U tezi su korišćeni podaci dobijeni na osnovu terenskog mapiranja lokalnih populacija i podaci iz eksperimenta modelovanja kao i serija podataka dobijena cenzusom kolonija tekunica i terenskim uzorkovanjem zemljišta i vegetacije. Rasprostranjenje populacija oblikuju klimatski uslovi ali pored abiotičkih faktora uslovljavaju ih i biotički faktori i kretanje jedinki. Promena klime direktno utiče na distribuciju optimalnih uslova. Istraženo je u kojoj meri će doći do promene u distribuciji optimalnih uslova sredine za tekunicu. Potencijalna promena analizirana je uzimajući u obzir klimatski scenario Max Plank Instituta sa tri rcp projekcije i tri generisana prostorna scenarijadistribucije otvorenih travnatih staništa u Vojvodini. Sagledavanje mogućih efekata promene sredinskih uslova dalo je mogućnost da se ukaže na zone koja će biti ključne za očuvanje populacija tekunica i travnatih ekosistema u Vojvodini. Sledeće, s obzirom da disperzija jedinki, dostupnost resursa kao i delovanje lokalnih faktora ugrožavanja (barijere, menadžment staništa, varijabilnost sredinskih uslova, predatorstvo, poljoprivredne aktivnosti) oblikuju distribuciju populacija u prostoru, u radu je analiziran i uticaj promene ovih faktora na distribuciju populacija. Na području lokalnog slatino-stepskog koridora srednjeg Banata istražene su kompozicija biljnih vrsta, upravljanje na staništu, promena u kompoziciji okolnih poljoprivrednih kultura i dinamika populacije. Dobijene su informacije o efektima lokalnih uslova na prisustvo kolonija, veličinu kolonija i kondiciono stanje jedinki. Informacije dobijene u ovim poglavljima su kasnije korišćeni za formiranju seta kriterijuma radi karakterizacije svih mapiranih staništa u Vojvodini. Dalje, veliku ulogu u poljoprivrednom predelu imaju tranziciona staništa koja povezuju lokalne populacije. Identifikovanje koja tranziciona staništa koriste jedinke tekunice je ključno za očuvanje populacija i ublažavanje trena opadanja brojnosti. Na terenu su mapirani distribucioni obrasci lokalnih kolonija tekunice i istraženo je da li postoje razlike na lokalnom i predeonom nivou u distribuciji nastanjenih i napuštenih staništa na području Vojvodine. U radu je dalje analizirana mapirana mreža staništa lokalnih populacija i pretpostavljano je da populacije funkcionišu i održavaju se u okviru metapopulacione strukture. Sa druge strane, veličina i površina koju zauzimaju potencijalne metapopulacione struktura mapirane mreže staništa koje se razlikuju u odnosu na okupiranost, kapacitet i povezanost nisu bile poznate. Kako bi se kvantifikovale potencijalne metapopulacione jedinice i utvrdila vijabilnost svake definisane pojedinačne metapopulacione mreže korišćen je metod ključnog fragmenta. Mapirane mreže evaluirane su iz perspektive samog taksona i testiran je potencijalni disperzioni kapacitet. Proverena je permeabilnost predeonog matriksa između mapiranih staništa i identifikovani su potencijalni koridori za jedinke. Ovakav pristup daje uvid u koji deo predela je značajno i neophodno ulagati ograničena sredstva za zaštitu prirode unutar regiona Vojvodine. U tezi je na kraju ocenjen doprinos trenutne regionalne konzervacione prakse zaštiti staništa tekunice, dat pregled slabih tačaka i predlog predeono adaptacionih mera koji će doprineti zaštiti i očuvanju populacije tekunice kao i mozaika otvorenih travnatih staništa. The study analyzes the European ground squirrel (EGS) population response to land use and climate change in Vojvodina. The response of the EGS population (typical species of open grassland habitats and the ideal model organism) to changes in environmental conditions in this region will enable consideration of following measures at the local and landscape level: i) effective protection and conservation of the EGS and habitat it relay on; ii) climate change and land use mitigation and adaptation iii) how can we harmonize the development of agriculture and preserve the biodiversity of grassland ecosystem in agricultural settings. In order to answer the questions of this study, the field research was conducted, standard spatial approach and ecological modeling were employed. All applied techniques are complementary to one another in obtaining responses to the questions asked. The results of one analysis represent the input data for the following one. The data for the study were obtained: from EGS local populations’ field mapping, from the modeling experiment, the census campaigned and the field sampling of soil and vegetation. Distribution of populations, which in addition to abiotic factors are conditioned by biotic factors and movement of individuals were evaluated in the context of climate change. Climate change directly affects the distribution of optimalconditions. The potential changes in distribution of optimal environmental conditions for EGS were assessed by considering changes in abiotic factors and the availability of grasslands. The climate scenario obtained using a dynamic vegetation map with three rcp projections and three spatial scenarios for the distribution of open grasslands were used. The extrapolation of a suitable area obtained by presence only model Maxent gives the possibility to point to the zones that will be crucial for preserving the populations and grassland ecosystems in future. Dispersion of individuals, availability of resources and the operation of local threats (e. g. barriers, habitat management, variability of the central conditions, predation, agricultural activities) shape the distribution of populations in space and time. In the area of the local saline steppe corridor of the central Banat in Vojvodina i) the composition of plant species, ii) open grassland habitat management iii) changes in the composition of surrounding crops and iv) population dynamics of EGS have been investigated. The effects of local conditions on the presence, size of colonies and condition of the individuals of EGS were assessed. The information obtained in these chapters was later used to form a set of criteria for the characterization of all mapped habitats in Vojvodina. In the agricultural area, transitional habitats connect local populations of many species. Identifying transitional habitats which potentially can be used by focal species is key to protect and mitigate population decline. For this purpose distribution patterns of the colonies were mapped in the field. The haracteristics and differences among mapped patches at the local and sub landscape scale were detected and evaluated. Later in the study the network of mapped habitats patches was evaluated. It was assumed that mapped populations in Vojvodina function within several metapopulations networks. However, the size and area of potential meta-population networks are likely to differ in relation to occupancy, capacity and habitat connectivity. The knowledge of potential population units was scarce. In order to quantify the potential population units, to determine the viability and conservation priority of each defined habitat network the key patch approach was used. Mapped networks were evaluated from the perspective of the taxon itself and potential dispersed capacity was tested. The ermeability of the matrix area, connectivity of the mapped habitats and the distribution of potential corridors was verified. This approach gives an opportunity to assess to which part of the area and population it is necessary to invest limited resources for nature protection in Vojvodina.The contribution of current regional conservation practice to protection of EGS was evaluated, a brief overview of the weak points and the proposal of preciseadaptation measures that should be taken in Vojvodina are presented in final chapter. The results of this study propose the development of spatial adaption measures and conservation design that will contribute not only in preserving EGS and habitats it relay on but also other wild plant and animal species in this intensively used agricultural settings.
- Published
- 2019
49. Analiza uticaja aktivnosti sunca i meteoroloških parametara na koncentraciju 7Be u prizemnom sloju atmosfere
- Author
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Rajačić, Milica, Todorović, Dragana, Puzović, Jovan, and Đurđević, Vladimir
- Subjects
aproksimacija i predikcija ,radioaktivnost ,meteorološki parametri ,meteorological parameters ,7-beryllium ,Furijeova analiza ,7-berilijum ,Fourier analysis ,kosmičko zračenje ,cosmic radiation ,radioactivity ,Sun activity ,solar magnetic field strength ,approximation and prediction ,jačina Sunčevog magnetnog polja ,aktivnost Sunca - Abstract
Zbog svoje radioaktivne i toksične prirode, lokacije i načina nastajanja, izotop 7Be ima višedecenijsku pažnju u oblasti radioekologije i meteorologije, pre svega kao trasera u praćenju kretanja polutanata i vazdušnih masa. Shodno tome, bilo bi poželjno ustanoviti model vremenske distribucije ovog izotopa, koji bi omogućio predikciju njegove koncentracije. Kao doprinos poboljšanju odabira parametara za simulacione modele, cilj ovog istraživanja je da se ispita uticaj aktivnosti Sunca i pojedinih meteoroloških parametara na koncentraciju 7Be u prizemnom sloju atmosfere. Za potrebe ovog istraživanja, korišćeni su rezultati gamaspekrtometrijskog odreĎivanja koncentracije aktivnosti 7Be u dva medijuma (vazduh – uzorci aerosola i ukupni depozit) tokom perioda 1995–2017, sprovedenih u Laboratoriji za zaštitu od zračenja i zaštitu životne sredine, Instituta za nuklearne nauke “Vinča”. Metodama Furijeove transformacije i linearne regresije, primenjenim u ovoj disertaciji, po prvi put je uočena mogućnost uticaja smera Sunčevog magnetnog polja na koncentraciju 7Be u uzorcima vazduha. Pokazalo se da bi uključivanje perioda promene od 22 godine moglo dovesti do poboljšanja kvaliteta njene simulacije. Due to the 7Be isotope is radioactive and toxic nature, as well as its location and way of its production, it has decades of attention in the field of radiochemistry and meteorology, primarily as a tracker in monitoring the movement of pollutants and air masses. Accordingly, it would be desirable to establish a time distribution model for this isotope, which would allow a prediction of its concentration. As a contribution to improving the selection of parameters for simulation models, the aim of this study is to examine the influence of solar activity and individual meteorological parameters on the concentration of 7Be in the ground level atmosphere. For the purposes of this research, the results of gamaspekrtometric determination of the activity concentration of 7Be in two media (air - aerosols and total deposit) were used. They carried out at the Laboratory for Radiation Protection and Environmental Protection, Institute for Nuclear Sciences "Vinča" and cover the period during 1995-2017. The methods of the Fourier transform and linear regression, applied in this dissertation, for the first time have seen the possibility of influencing the direction of the Solar magnetic field to the concentration of 7Be in air samples, and it has been shown that the inclusion of a period of change of 22 years can lead to a decline in the quality of its simulation.
- Published
- 2019
50. Objektivna klasifikacija atmosferske cirkulacije iznad Srbije
- Author
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Putniković, Suzana M., Tošić, Ivana, Unkašević, Miroslava, Ruml, Mirjana, and Đurđević, Vladimir
- Subjects
cirkulacioni tipovi ,postepena regresija ,padavine ,seasons ,atmospheric circulation ,cirkulacija atmosfere ,temperature ,Srbija ,stepwise regression ,sezone ,precipitation ,Serbia ,circulation types - Abstract
Vreme i klima neke oblasti odraz su na prvom mestu osobenosti opšte cirkulacije atmosfere. Promene u atmosferskoj cirkulaciji su presudne zato što su one često praćene promenama u površinskim meteorološkim promenljivama. Da bi se lakše proučavala veza između atmosferske cirkulacije i lokalnih vremenskih uslova, vrši se klasifikacija sinoptičkih sistema, tj. određuju se tipovi cirkulacije. Zato je glavni cilj ove disertacije da se na objektivan način identifikuju i opišu tipovi cirkulacije koji karakterišu vremenska stanja iznad Srbije. Proučavanje tipova cirkulacije je aktuelna tema, koja se stalno unapređuje i dopunjuje. Metod Jekinson-a i Collison-a je objektivna verzija Lamb-ove klasifikacije atmosferske cirkulacije, gde je dnevna cirkulacija okarakterisana upotrebom indeksa povezanih sa pravcem, jačinom i vrtložnošću strujanja. Ovaj metod je bio primenjen iznad Srbije za period od 1961. do 2010. Dobijeno je dvadesetšest cirkulacionih tipova: osam usmerenih tipova po pravcu − severni (N), severoistočni (NE), istočni (E), jugoistočni (SE), južni (S), jugozapadni (SW), zapadni (W) i severozapadni (NW), zatim dva vrtložna tipa zasnovana na jačini vrtložnosti − ciklonalni (C) i anticiklonalni (A) i šesnaest hibridnih tipova (osam ciklonalnih i osam anticiklonalnih za svaki pravac). Sinoptičke karakteristike dobijenih tipova su razmatrane za sve četiri sezone. Svaki cirkulacioni tip ima poseban sinoptički obrazac koji daje očekivan tip i smer strujanja iznad posmatrane oblasti. Analizirani su i trendovi i relativne učestalosti cirkulacionih tipova. Mana metoda Jekinson–a i Collison–a je što nema podataka na višim nivoima. Ovaj nedostatak je rešen u disertaciji tako što su analizirane anomalije geopotencijalne visine na 500 hPa. Utvrđeno je da je anticiklonalni (A) cirkulacioni tip najučestaliji u jesen (23,87%), zatim zimi (18,93%) i u leto (18,70%). Sledi severoistočni tip (NE) sa čestinom od 16,65% za vreme letnje sezone. A tip ima pozitivan trend za zimu i proleće i statistički značajan negativan trend za jesen i leto. C tip pokazuje značajno negativan trend samo u proleće... One of the primary dynamic factors shaping weather and climate of an area is the atmospheric circulation. Regional or local changes in meteorological parameters in the mid-latitudes are mainly controlled by the atmospheric circulation. In order to study relationships between atmospheric circulation and local weather conditions, classification of the synoptic systems is conducted, i.e., circulation weather types (WTs) are determined. Therefore, the main goal of this thesis is to objectively determine and explain the circulation weather types over Serbia. Studying of circulation types is a current topic that is constantly improved and updated. The method of Jenkinson and Collison is an objective version of the Lamb’s classification of atmospheric circulation, in which daily circulation is characterized using a set of indices associated with the direction, strength and vorticity of the flow. This method has been applied to the atmosphere over Serbia for the time period 1961- 2010, resulting in 26 WTs: eight pure directional types - northerly (N), northeasterly (NE), easterly (E), southeasterly (SE), southerly (S), southwesterly (SW), westerly (W) and northwesterly (NW), two pure types based on the severity of the vorticity - cyclonic (C) and anticyclonic (A), and sixteen hybrid types (eight cyclonic and eight anticyclonic for each direction). Synoptic characteristics of circulation types against all four seasonal times are considered. Each of the circulation types has a distinct underlying synoptic pattern that produces the expected type and direction of flow over the study area. Trends and relative frequencies of the circulation types are analyzed. A shortcoming of this method is the lack of data on other higher levels. In thesis, this deficiency has been solved by the vertical structure of the atmosphere that was employed to analyze the anomalies of the geopotential height at the 500 hPa. It has been found that the anticyclonic type (A), is the most common type of circulation in autumn with a frequency of 23.87%, then winter (18.93%) and summer (18.70%), followed by the northeasterly type (NE) with a frequency of 16.65% during the summer season. The A type has a positive trend for winter and spring, and significant negative trend for autumn and summer. The C type shows a significantly negative trend only in spring...
- Published
- 2017
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