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The most significant effects of climate change are related to temperature and precipitation. Changes in precipitation and temperature patterns affect water resource capacity, agricultural activities, global biodiversity and emergency management. In this study, using two statistical models (Mann-Kendall and Pettit’s test), climate data for the territory of Belgrade in the time interval 1961-2020 were processed. Trends were analyzed: average annual temperatures, average monthly temperatures, annual and monthly precipitation amounts. The aim of the research is to determine the statistical significance of the increasing/decreasing temperature and precipitation trends on a monthly and annual basis. Based on the obtained results, it was determined that the changing point of the annual temperature is in 1997, while a statistically significant increasing trend was observed in all months except November. The increasing trend recorded by the precipitation amount is 0.345 mm/year, but without statistical significance. The most significant results corresponding to July and October. [ABSTRACT FROM AUTHOR]

Recently, extreme climatic events have been a major concern across the world. Assessments on various climates and geographic regions are needed to understand the uncertainties in extreme climate events' responses to global warming. Developing countries particularly Ethiopia is highly affected by such extreme climate events due to its low adaptive capacity. The aim of this study was to investigate the trends of daily extreme temperatures indices in Ethiopia. The changes and trends in climate extremes of temperature were evaluated based on 14 indices of extreme temperatures over Ethiopia. The Mann-Kendall (MK) trend test is used to investigate the trends in the selected datasets. In the present study, three zones, which represent 34 stations, were selected based of extreme climate indices. The results of 14 extreme temperature indices showed that warm days (TX90p) and nights (TN90p) increased by 2.65 (P < 0.05) and 2.04 (P < 0.05) days/decade, respectively. The annual maximum and minimum temperatures (TXam and TNam) as well as the diurnal temperature range (DTR) were 2.68/decade, 2.04/decade and 0.62/decade, respectively. 73.5% and 26.5% of the stations show an increasing trend for (TXx and TNx), respectively. The extreme hot temperature indices (TXx, TXn, TX90, TN90 and SU) and cold temperature indices (ID, TNn, TXn, TX10P, TN10P and FD) exhibited contrasting variations over the stations. As far as spatial patterns concerned, most of the stations show significant increasing trends in northern and southeastern parts of Ethiopia. Thus, changes in climate extremes will likely increase the risk of severe extreme events and the society to become more vulnerable to the climate shocks. Generally, the findings of this study could help decision and policymakers to take immediate measures to tackle the climate change impacts. [ABSTRACT FROM AUTHOR]

Estimation of evapotranspiration, representing a highly sensitive variable to global warming, is often required in water resources and agricultural studies. This study explores the possible effects of climate change on evapotranspiration (ETo) across Iran. The ETo was computed using the Penman‐Monteith Temperature (PMT) method that requires only minimum and maximum temperature (Tmin and Tmax), provided by the NASA Earth Exchange Global Daily Downscaled Projections dataset (NEX‐GDDP) with a 0.25° × 0.25° spatial resolution. Accuracy of the NEX‐GDDP Tmin and Tmax were evaluated against ground truth observations at 41 synoptic weather stations distributed across the country using a set of statistical measures, including the coefficient of determination (R2) and Nash‐Sutcliffe Efficiency (NSE). Similarly, the PMT estimated evapotranspiration based on the NEX‐GDDP Tmin and Tmax (ETo‐GDDP) were statistically evaluated against the ETo computed with observed variables at selected stations (ETo‐obs). Then, at each grid cell, the 45‐years ETo‐GDDP time series was partitioned into three 15‐years subperiods such that the differences between three subperiods were computed and inter‐compared. Furthermore, annual, seasonal, and monthly ETo time series trends of each cell were evaluated using the Mann–Kendall trend test (MK) while the corresponding change rates were estimated using Theil–Sen's slope estimator (TSSE). The results demonstrated a good agreement between ETo‐GDDP and ETo‐obs with R2 greater than 0.8 and NSE greater than 0.7 in 90.2% and 65.8% of the stations, respectively. The maps of differences between the three subperiods showed negligible changes in ETo between 1975–1990 and 1950–1975 subperiods. The spatial patterns of annual and seasonal MK statistics showed a significant increasing trend in most parts of Iran. On seasonal scale, the highest and lowest ETo changes were observed in spring (0.00035–0.0045) and in autumn (0.0005–0.0015), respectively. [ABSTRACT FROM AUTHOR]

This study was aimed to use GIS techniques in climate studies. Analysis of monthly wind speed data for the period 1981 to 2017, and mapping of monthly, seasonal and annual wind speed in Iraq has been investigated in this study. The area of study was divided into three regions. the results of Mann Kendall test of the middle and southern region reveal a significant decreasing trend in the months of the summer season. While positive trends of mean wind speed were found in the northern region for the whole period. Wind speed value reaches its highest value in (Jun and July), and the lowest value of wind speed was in December. Seasonal wind speeds show the highest values recorded in the summer and spring seasons and the lowest in the autumn and winter seasons. Wind speed maps were obtained using IDW techniques in G I S, the results show that the annual average of wind speed in the northern, middle and southern regions was 2.7 m/s, 3.6 m/s and 4.1 m/s respectively. While the annual average of wind speed in the study area "Iraq" was 3.6 m/s. The winds were low in the northern region compared to the middle and southern regions. The wind speed maps show the appropriate sites for the installation of wind turbines. [ABSTRACT FROM AUTHOR]

Hourly ground-level ozone (O 3) data from 52 monitoring stations in Poland were analyzed over a ten-year pre-COVID19 period (2010–2019) to map and define areas at risk for human health and vegetation, and to calculate trends over the study period. Annual O 3 metrics (24-h average concentrations, 50th percentiles, and hourly maxima), human health metrics (Sum Of daily maximum 8-h Means Over 35 ppb, SOMO35, summertime average of the daily 8-h maximum O 3 concentrations, O 3 MDA8, and number of daily maximum 8-h values above 60 ppb, EU60) and vegetation exposure metrics (AOT40, i.e., accumulation of hourly O 3 concentrations exceeding 40 ppb during the growing season for agricultural crops AOT40c and forests AOT40f) were investigated. Higher O 3 levels occurred in rural areas than in cities. Between 2010 and 2019, the O 3 levels were rising in both urban and rural areas. Despite the reduction of nitrogen oxides (NO x : - 2.33% year-1) and volatile organic compounds emissions (VOCs: - 0.95% year-1), annual O 3 mean levels (+0.81 and +0.12% year-1), 50th percentiles (+1.06 and ∼0% year-1), hourly maxima (- 0.10 and +0.23% year-1), SOMO35 (+2.86 and +1.50% year-1), summertime O 3 MDA8 (+0.49 and +0.48% year-1), EU60 (+0.09 and +0.15 days year-1), AOT40c (+3.79 and +3.29% year-1) and AOT40f (+4.47 and +4.34% year-1) commonly increased in urban and rural stations. The O 3 levels increased at 75.0% of urban stations and 62.5% of rural stations. A slight decline of the number of O 3 peaks occurred in cities, likely driven by the recent reductions in NO x emissions by on-road transport. For all metrics, the increase can be attributed to higher regional photochemical O 3 formation and rising background O 3 levels likely driven by imported O 3 and its precursors by long-range transport, climate change, and lower O 3 titration by NO x emissions decline. The failure to attain the target value for O 3 for protecting vegetation and human health and vegetation persists. Southeastern Poland, where coal stoves are still used for residential heating, faces the highest O 3 risk. This study reports new information on surface O 3 levels, exceedances, and trends in Poland to develop effective policies to mitigate O 3 effects. [Display omitted] • We calculated human health and vegetation exposure O 3 metrics for Poland. • We calculated short-term trends for O 3 metrics over the pre-COVID19 period (2010–2019). • We used an interpolation approach to map O 3 exposure for risk assessment. • We found that the O3 baseline level is rising in both urban and rural areas. • We discussed spatial distribution of levels and changes in O 3 levels. [ABSTRACT FROM AUTHOR]

A basic statistical data analysis and trend analysis were performed for the flows recorded at the Tisne Stine 1 gauging station on the Cetina River. The analysis was carried out using the linear and nonlinear regression, Mann-Kendall test, and the so-called RAPS method. [ABSTRACT FROM AUTHOR]

A basic statistical data analysis and trend analysis were performed for the flows recorded at the Tisne Stine 1 gauging station on the Cetina River. The analysis was carried out using the linear and nonlinear regression, Mann-Kendall test, and the so-called RAPS method. [ABSTRACT FROM AUTHOR]

GNSS technique is important in climate studies because of obtaining Zenith Total Delay which is significant parameter to determine weather conditions with analysis of GNSS observations. Interchanges of long term data can be detected via trend analysis produced by ZTD time series data. In this study, trend and serial correlation effect of time series of (IGS Repro1) were investigated using between 1995-2010 reprocessed ZTD data in the framework of COST Action ES1206, GNSS4SWEC (Advanced Global Navigation Satellite Systems Tropospheric Products for Monitoring Severe Weather Events and Climate). Mann-Kendall test was performed for nonparametric method. The autocorrelation coefficient was calculated to set the serial correlation. Trend-Free Prewhitening method has been applied to eliminate the correlation. The effect on the trend determination of serial correlation and the performance of Trend-Free Prewhitening method were tried to made examination by making re-trend analysis in series which eliminated correlation. As a result of the performed methods, serial correlation is substantial whole ZTD data. At the same time, there are trends in LAMA, ONSA and PENC stations after applying Trend-Free Prewhitening. In this work, MATLAB programming language was handled in all of the tests. [ABSTRACT FROM AUTHOR]

Highlights • The spatial variability of the long-term trends of the SWH in the Black Sea was studied. • Wave fields were hindcasted by Mike21 SW for the last 38 years. • Long-term trends are estimated by the Theil-Sen and line of best-fit estimators. • Severe sea states resulted in more significant and steeper trends than the mean values. • Correlations of SWH to climate oscillation indices were studied. Abstract This study aims to estimate the spatial variability of the long-term trends of Significant Wave Height (SWH) in the Black Sea. A spectral wave model was used to hindcast 38 years of SWH forced by ECMWF ERA Interim wind fields. Long-term trends were estimated from normalized SWH (NSWH) data, for each month separately, by using two non-parametric methodologies; Line of best fit and the Theil-Sen estimator, and then mapped to show their spatial variability. Maps were generated for both mean SWHs and 95th percentile SWHs, the latter is considered to reflect the trends of the severe sea states. The basin-averaged analysis was also carried out to investigate the general tendency of SWHs in the Black Sea. The significance of the trends was evaluated by using Mann-Kendall test. The annual mean SWH is found to be increasing (up to 1.6%/year) in the eastern part of the Black Sea while the western part has a negative trend (down to −1.2%/year). Long-term analysis of the 95th percentile SWHs revealed steeper trend slopes and higher statistical significance compared to the mean SWH trends, showing that storm SWHs have a higher tendency to increase than the mean SWHs. Statistically significant correlations between climate indices; North Atlantic Oscillation (NAO), Arctic Oscillation (AO), Antarctic Oscillation (AAO), Atlantic Multidecadal Oscillation (AMO), Pacific North American (PNA), East Atlantic (EA), East Atlantic/West Russia (EA/WR), Scandinavia (SCAND), Niño3 and the Black Sea wave fields were identified. [ABSTRACT FROM AUTHOR]

In the present study, we conducted a risk assessment of urban population exposure to ambient particles (PM 2.5 , PM 10), nitrogen dioxides (NO 2), and tropospheric ozone (O 3) in six Polish urban areas over the period 2015–2020. The main goals were to: i) evaluate the number of premature deaths attributed to ambient air pollutants, and to ii) assess the effectiveness of emissions control policies in reducing urban population exposure to air pollution, and thus related health effects. For that, we used air quality data from 15 urban monitoring stations and city-specific health data (relative risk values and baseline incidence). For all cities, the annual PM 2.5 , PM 10 , and NO 2 mean concentrations exceeded the 2021 World Health Organization Air Quality Guidelines in 2015–2020. In all cities, the annual PM 2.5 (- 0.5% to - 6.1% year−1), PM 10 (- 1.6 to - 8.1% year−1), and NO 2 (- 1.3% to - 4.5% year−1) mean concentrations declined over time, while O 3 levels rose (+1.0% to + 4.2% year−1). Exposure to ambient PM 2.5 , PM 10 , NO 2 , and O 3 has substantially contributed to mortality in the six studied cities: a total of 6700 deaths for non-accidental causes, 2310 deaths for cardiovascular diseases, and 500 deaths for respiratory diseases were reported. Between 2015 and 2020, the number of annual PM 2.5 -, PM 10 -, and NO 2 -related premature deaths decreased (respectively, by - 8.4, - 6.7, and - 2.1 deaths per 106 inhabitants) in line with cleaner air. The rising O 3 levels led to an increase in annual O 3 -related premature deaths (+1.3 deaths per 106 inhabitants) over time. A major concern is related to the overrun of exposure metrics compared to the target values for human health. To date, human health is mainly threatened by PM 2.5 and O 3 , particularly in Southern Poland. • Risk assessment of urban population exposure to main air pollutants in Poland in 2015–2020. • PM 2.5 , PM 10 , and NO 2 mean concentrations declined while O 3 levels rose. • About 6700 premature deaths are attributed to air pollution in 2015–2020. • PM 2.5 -, PM 10 -, and NO 2 -related deaths declined: 8.4, - 6.7, - 2.1 deaths per 106 people. • Rising annual O 3 -related number of premature deaths: +1.3 deaths per 106 people. [ABSTRACT FROM AUTHOR]

The aim of this paper is to examine the spatial and temporal variability of the average monthly, seasonal and annual air temperatures in Serbia. Therefore, data from 64 climatologic stations were analyzed in the period from 1961 to 2010. Based on the data, on the position of the stations (their latitude, longitude, altitude), and the characteristics of the terrain in their vicinity (inclination and terrain exposure in a radius of 10 km around the station), a regression model was constructed based on which air temperatures are interpolated for the territory of Serbia. The rootmean- square error (RMSE) of the regression model ranged from 0.2 °C in January, February and November to 1.1 °C in August. Spatial distribution of air temperatures is shown (maps of mean monthly, mean seasonal and mean annual air temperatures are made), and the Sen's procedure was used to calculate trends of air temperatures (maps of average monthly, mean seasonal and mean annual trends of air temperatures). The Mann-Kendall test was used to test the significance of air temperature trends. Apart from the southeast, the whole territory of Serbia has practically experienced a statistically significant rise in the average annual air temperature, with the highest increase in the summer and winter months. [ABSTRACT FROM AUTHOR]

ABSTRACT The objectives of this study were to investigate the trend in annual precipitation, sunshine duration, wind speed ( u2), and annual and monthly minimum temperature ( Tmin), maximum temperature ( Tmax), and relative humidity ( RH) and the adaptation strategies for the Senegal River Basin. Annual precipitation, Tmin, Tmax, RH, sunshine duration, and u2 for the period of 1950-2000 recorded at St-Louis, Bakel, Dagana, Fanaye, Podor, and Matam have been analysed using the Mann-Kendall test and Sen's slope estimator. Annual precipitation varied with location from 900 mm registered in 1967 at Bakel to 32 mm obtained at Dagana in 1986. A significant decreasing trend ( p < 0.001) in precipitation was observed at Podor, Dagana, Matam, Bakel, and St-Louis. A non-significant decreasing trend in annual precipitation was observed at Fanaye Dieri. There was a significant increasing trend ( p < 0.001) in Tmax and Tmin at all locations. Sunshine duration had a significant decreasing trend at Podor, Matam, and St-Louis at the rate of 0.27, 0.28, and 0.35 h decade−1, respectively. RH and u2 have differences in their trends, with the first one showing a strong and significant decrease and u2 with less significance in their trends. The trend analysis in the climate variables revealed a change in climate that necessitates some specific actions for resources management sustainability and conservation. [ABSTRACT FROM AUTHOR]

ABSTRACT Evapotranspiration is a sensitive parameter for assessing climate change. It controls energy and mass exchange and is a descriptor of drought in arid- and semi-arid regions. Using the Mann- Kendall ( M-K) test, Sen's slope estimator, and the stepwise regression, temporal, and spatial variations in potential evapotranspiration ( ET0) and its dominant factors were analysed. The analysis was based on data from 173 meteorological stations in a desertification-prone region of China over the period from 1960 to 2013. The annual ET0 decreased prior to 1990s and increased thereafter. The majority of stations had a decreasing ET0 trend, especially in summer, in which the average slope of all stations was −2.43 mm decade−1. Analysis of determining factors showed that a decrease in wind speed was the primary factor associated with decreasing ET0. The trend magnitude of ET0 increased from −2.25 mm decade−1 to −7.43 mm decade−1 as wind speed increased, then decreased to −3.00 mm decade−1. Decreasing ET0 and increasing P in the western region led to decrease in the aridity index, suggesting a wetter climate and reduced desertification. Increasing aridity index in the eastern region reduced the vegetation cover and facilitated desertification processes, which might be a disadvantage for ecological reconstruction and desertification control. Better understanding of the response of ET0 to regional climate change may facilitate efficient use of limited water resources and establish management strategies that can combat desertification and maintain ecological security in a desertification-prone region. [ABSTRACT FROM AUTHOR]

The hourly ozone (O 3 ) data from 332 background monitoring stations, spread in France, were analyzed over the period 1999–2012 and short-term trends were calculated. In the current climate change context, the calculation of human health- and vegetation-relevant metrics, and of associated trends, provides a consistent method to establish proper and effective policies to reduce the adverse O 3 effects. The generation of optimal O 3 maps, for risk and exposure assessment, is challenging. To overcome this issue, starting from a set of stations, a hybrid regression-interpolation approach was proposed. Annual surface O 3 metrics, O 3 human health metrics (number of exceedances of daily maximum 8-h values greater than 60 ppb and SOMO35) and O 3 vegetation impact metrics (AOT40 for vegetation and forests) were investigated at individual sites. Citizens are more exposed to high O 3 levels in rural areas than people living in the cities. The annual mean concentrations decreased by −0.12 ppb year −1 at rural stations, and the significant reduction at 67% of stations, particularly during the warm season, in the number of episodic high O 3 concentrations (e.g. 98th percentile, −0.19 ppb year −1 ) can be associated with the substantial reductions in NO x and VOCs emissions in the EU-28 countries since the early 1990s Inversely, the O 3 background level is rising at 76% of urban sites (+0.14 ppb year −1 ), particularly during the cold period. This rise can be attributed to increases in imported O 3 by long-range transport and to a low O 3 titration by NO due to the reduction in local NOx emissions. The decrease in health-related and vegetation-relevant O 3 metrics, at almost all stations, is driven by decreases in regional photochemical O 3 formation and in peak O 3 concentrations. The short-term trends highlight that the threat to population and vegetation declined between 1999 and 2012 in France, demonstrating the success of European control strategies over the last 20 years. However, for all exposure metrics, the issue of non-attainment of the target value for O 3 persists in comparison with the objectives of air quality directives. The region at highest O 3 risk is the South-eastern France. This study contains new information on the i) spatial distribution of surface O 3 concentration, ii) exceedances and iii) trends to define more suitable standards for human health and environmental protection in France. [ABSTRACT FROM AUTHOR]

Several studies have shown that the stream water quality in agricultural catchments could vary according to the changes in land use, production intensities and implemented agri-environmental measures. In present study we investigated the nitrogen content and temporal dynamics in concentration and loss in small streams and catchments in Estonia for the period 1992–2011. The studied catchments represent various agricultural production areas, management practices, soil types, geology and size. A statistical analysis using the Mann Kendall (MK) test was undertaken to discern monotone trends in time series of total nitrogen (TN) and nitrate nitrogen (NO 3 –N) concentrations for 8 sampling sites and TN loss for five sites, for which at least a data set of 10 years was available. Additionally the partial Mann–Kendall (PMK) test has been adapted to account for the influence of water discharge to the temporal trends in TN loss in five catchments. The MK trend test revealed one statistically significant ( p < 0.05; two-sided test) upward trend in TN concentrations and two upward trends in NO 3 –N concentrations. Less significant ( p < 0.08) upward trend in TN content was also noted in two streams. Overall, the TN concentrations were rather high and it ranged with 90% probability from 2.3 to 8.9 mg l −1 in the studied streams. The MK test revealed the statistically significant upward trend in TN loss only at the Räpu ( p < 0.001) and Jänijõgi ( p < 0.05) catchments (one-sided test). After conditioning on trends in water discharge there was only one (Räpu) statistically significant temporal upward trend in TN loss. Elevated nitrogen concentrations in three other catchments (Rägina, Vodja, Porijõgi) explain only part of the upward trend in nitrogen losses and increasing tendencies in losses could mainly be associated with upward tendency in discharge. The direct (not flow-normalised) unit-area loss of nitrogen from agricultural land reached to 63.1 and 82.5 kg N ha −1 yr −1 in the Räpu and Jänijõgi catchments, respectively, which is higher than seen at the Rägina basin (25 kg ha −1 yr −1 ) and the River Vodja catchment (21.9 kg ha −1 yr −1 ). Elevated losses are typical for recent years, particularly after 2007. [ABSTRACT FROM AUTHOR]

For sustainable water resource management, it is important to determine the relationship between streamflow and other variables that influence availability of water resources. However, many catchments do not have sufficient data to allow for a more detailed study of these relationships. We faced a similar challenge in the Chengcun Basin (limited historical data: from 1986-1999); and therefore we used a new approach to overcome this. We found that, using nonparametric trend methods in conjunction with the climate elasticity analyses and the 2D visualization of hydrologic data, it is possible to assess the relationships between streamflow and other hydro-climatic variables. In the past, streamflow trends in the basin were more correlated with precipitation than with potential evapotranspiration (PET). In addition, there is a gradual shift in the hydrological regime of the catchment, which may affect the occurrence of available water resources and activities that depend on them. In addition, based on our climate sensitivity analyses, the streamflow is dependent and more sensitive to variations in precipitation than to PET (δ Q=0.79δ P+0.42δ E; precipitation elasticity, ɛ =1.32; PET elasticity, ɛ =−2.10). Therefore pending more detailed studies, the use of our approach will provide a rapid means to assess the variation of water resources (streamflow) in a watershed. In the future, we hope to carry out related research in other watersheds and also perform a more detailed studies to improve upon the results of this study. [ABSTRACT FROM AUTHOR]

Abstract: Analyzing hourly ozone data from 214 European background sites over the time period 2000–2010, we demonstrated for the first time that the ozone control measures are effective at rural sites, while ozone concentrations are still increasing in the cities. The Western European Mediterranean basin is expected to be more strongly affected by climate change, including ozone pollution, than most of the other regions of the world. At 58% of the rural sites significant decreases were found resulting in an average – 0.43% per year while an increase was recorded in urban and suburban stations (+0.64% year−1 and +0.46% year−1, respectively). At cities ozone average levels increased, but the peak ozone concentrations decreased. In all station types, a significant reduction in the amplitude of peak ozone concentrations was found at more than 75% of stations (98th percentile, −0.77% year−1; hourly peak, −1.14% year−1 and daily average peak, −0.76% year−1). The peak reduction may largely be attributed to the reduction in NO x and VOC emissions within the European Union which started in the early 1990s. The results suggested a convergence of ozone pollution at remote and urban sites all around the Western European Mediterranean basin. [Copyright &y& Elsevier]

Abstract: Long term (2000–2010) analysis of hourly surface ozone data from 6 out of 9 background air pollution monitoring sites in Portugal shows prominent secondary/nocturnal peak in monthly averaged diurnal variation during winter months (Nov–Feb). Of 9 sites: 3 are urban, 5 suburban and 1 rural. The bimodal diurnal variation of surface ozone shows a major peak around 15 h and a minor peak around 03–05 h with minima around 08 h and 20 h in the months of November–February. During winter months, more than 50% of observations in Porto and Lisbon region had nocturnal surface ozone concentrations higher than 40 μg m−3 compared to monthly averaged early morning/late evening minima (20±5 μg m−3). Analysis also shows an increasing trend in nocturnal surface ozone daily maxima over 5 urban/suburban sites and over another site (Alfragide) which exhibits the same trend but only in the last 7 years of the studied period. Also the non-parametric Mann–Kendall test confirms that the trends are statistically significant. The enhancement of nocturnal surface ozone is most likely associated with transport process and prevailing meteorological conditions since photochemical production of ozone ceases after sunset. [Copyright &y& Elsevier]

Abstract: The nonparametric Mann–Kendall test was used to detect the trends of major hydroclimatic variables in the Tarim River Basin, the largest inland river basin in China for the period of 1960–2007. Results showed that both mean annual air temperature and precipitation experienced an increasing trend, while annual streamflow demonstrated a mixed trend of decreasing and increasing: The mountainous region upstream showed an increasing trend and the region downstream exhibited a decreasing trend. Impacts of the increased air temperature on streamflow have shown different characteristics depending on location and seasons: it has positive effect on the runoff at mountainous region due to snowmelt and glacier-melt in spring, but negative effect on the runoff at plain area due to the increase of actual evaporation in summer. In addition, human activity contributed to the declining of streamflow in the arid plain oases at downstream of the Tarim River Basin. The results obtained in this paper can be used as a reference for the planning and management of water resources to maintain the health of the river system. [Copyright &y& Elsevier]

Trends in annual and seasonal drought patterns in Turkey were investigated on the basis of regionally averaged surface humidity index (SHI) series. For this purpose, two nonparametric approaches, Mann-Kendall test and Sen's T test, were used. For some regions, significant upward trends in fall SHI series were detected due to the increasing precipitation for the period 1951–1998. The North Atlantic Oscillation influences on the SHI series were also investigated and significant negative correlations were found for some regions. [ABSTRACT FROM AUTHOR]

For the purpose of detecting the possible long-term trends of Japanese precipitation, both parametric t-test and nonparametric Mann–Kendall and Mann–Whitney techniques are applied to the spatially averaged precipitation time series over Japan. The results indicate that although several step changes occurred in Japanese precipitation, the time series did not exhibit significant evidence of monotonic trend during the past century. When a step change is present, the number of observations required for detecting the trend of a given magnitude at a specified significance and power level is investigated with the power function of the t-test. Results indicate that if the magnitude of the step change reaches one or two times of its standard deviation, the previous 50-year of record together with 5 years or more of new data will be available for detecting the possible trend. This conclusion may be helpful for the detection of step changes in the regions where the precipitation has near-normal distributions. [Copyright &y& Elsevier]

Studying weekend-weekday variation in ground-level ozone (O 3) allows one to better understand O 3 formation conditions, with a potential for developing effective strategies for O 3 control. Reducing inappropriately the O 3 precursors emissions can either produce no reduction or increase surface O 3 concentrations. This paper analyzes the weekend-weekday differences of O 3 at 300 rural and 808 urban background stations worldwide from 2005 to 2014, in order to investigate the O 3 weekend effect over time and assess the effectiveness of the precursors emissions control policies for reducing O 3 levels. Data were analyzed with the non-parametric Mann-Kendall test and Theil-Sen estimator. Rural sites typically did not experience a weekend-weekday effect. In all urban stations, the mean O 3 concentration on the weekend was 12% higher than on weekdays. Between 2005 and 2014, the annual mean of daily O 3 concentrations increased at 74% of urban sites worldwide (+ 0.41 ppb year−1) and decreased in the United Kingdom (- 0.18 ppb year−1). Over this time period, emissions of O 3 precursors declined significantly. However, a greater decline in nitrogen oxides (NO x) emissions caused an increase in Volatile Organic Compounds (VOCs) to NO x ratios leading to O 3 formation. In France, South Korea and the United Kingdom, most urban stations showed a significant upward trend (+ 1.15% per year) for O 3 weekend effect. Conversely, in Canada, Germany, Japan, Italy and the United States, the O 3 weekend effect showed a significant downward trend (- 0.26% per year). Further or inappropriate control of anthropogenic emissions in Canada, Southern Europe, Japan, South Korea and the United States might result in increased daily O 3 levels in urban areas. • Urban ozone levels generally showed increasing trends over time: + 0.35 ppb year−1. • Ozone pollution is becoming a major environmental concern in cities. • The ozone weekend effect increased in France, South Korea, and the United Kingdom: + 1.15% year−1. • It did not increase in Canada, Germany, Italy, Japan and the United States: - 0.26% year−1. • Ozone control in cities should be planned considering the ozone chemical regime. [ABSTRACT FROM AUTHOR]

Climate is an important and determining factor affecting many agricultural products. Diurnal temperature range (DTR) is an effective parameter in assessing climate change impacts on environment in a region. This parameter is determined by the difference between minimum and maximum air temperatures. In this study, changes in the daily DTR collected from 11 synoptic stations were analyzed. The selected sites cover 50 years of daily observations from 1956 to 2005, specifying suitable geographical distribution throughout the country. Kolmogrov-Smirnov test was used to check the normal distribution and Run-test to control the quality of the temperature data. Trend investigation of DTR data was carried out by using Mann-Kendall test (MK) and linear regression method (LR) at 95 percent confidence level for monthly and annual time scales. About 18 percent of the study sites showed no significant DTR trend, but the rest of the sites (82%) revealed significant negative (decreasing) trends for the observed diurnal temperature difference time series. However, few months experienced no DTR trend in the selected sites. In about 95.5 percent of the studies cases, the existence of trend and the decreasing DTR trends obtained by MK test were also confirmed by the LR method. In this research, the minimum and maximum slopes were determined by the LR method. The analysis of the measured temperature data showed an average decreasing in DTR slope about -0.445°C per decade for the selected sites. According to the results, the decreasing DTR trends in northern and central sites were more significant than those in the [ABSTRACT FROM AUTHOR]