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Long‐term precipitation monitoring plays a vital role in water resource management and disaster prevention and mitigation. This study assesses spatial and temporal trends in seasonal and annual precipitation in Pakistan between 1960 and 2016 at an interannual scale. The Mann–Kendall (MK) test, Sen's slope (SS) estimator, and Sequential Mann–Kendall (SQMK) test were employed to assess trends. Cluster analysis and L‐moment approach were used to identify the homogenous precipitation regions. In general, increasing precipitation trends between 1960 and 2016 were evident. Results indicated increasing precipitation in winter, autumn, summer and annual scale at the rates of 0.20, 2.18, 5.16, and 10.89 mm·decade−1, respectively. In spring, the precipitation trend shows a decreasing trend at −0.67 mm·decade−1. Moreover, a significant decreasing trend occurred in winter in southern Pakistan. The overall increasing trends were more noticeable between 1960 and 1988, compared to the declining precipitation during 1989–2016. SQMK analysis indicates a clear downward trend in most regions during 1989–2016, except in autumn. Annual precipitation has increased topographically except at 500 m and 1,500 m during 1960–2016 with a significant increase of 1.37 mm·decade−1 at elevation <250 m. Results indicate a negative correlation in SS test value with seasonal and annual precipitation with elevation and a positive correlation in winter. The seasonal and annual precipitation trends exhibit increasing and decreasing trends before and after 1990, respectively, in most subregions. The notable finding based on the outcomes of this study is that the whole country observed an increasing trend during 1960–1988, followed by a decreasing trend in during 1989–2016. This decreasing tendency is particularly pronounced between 1985 and 1995, except in autumn. Agriculture production is largely reliant on precipitation in many regions. So, a detailed study of the influence of monsoon trends and large‐scale climatic variability controls over Pakistan is vital for improved water resource management in the context of global warming and rising human activity. The results will help policy makers while establishing and updating water‐related initiatives and regulations. [ABSTRACT FROM AUTHOR]

Rainfall is time concentric in nature. The spatial and temporal distribution of rainfall is changing over the Earth with recent anthropogenic warming. The study explores various characteristics of annual and seasonal concentration of rainfall across India using the precipitation concentration index (PCI) and its trends during the period of 1986–2015, based on a high‐resolution gauge‐based rainfall data (0.25 × 0.25°), obtained from the India Meteorological Department (IMD). An intercomparison is made with 11 other gridded rainfall datasets to infer whether these datasets can reasonably reproduce the spatiotemporal distribution of PCI and its trends in various homogenous rainfall regions of India or not. These datasets are categorized into gauge‐based (APHRODITE, GPCC, CPC), satellite‐derived (CHIRPS, PERSIANN‐CDR), and reanalysis (JRA‐55, MERRA‐2, NCEP‐2, PGF, ERA‐Interim, ERA‐5). On annual scale, about 8.52, 24.1, and 67.38% of area of India are under moderate, irregular, and strongly irregular rainfall distribution, respectively. Spatial variation of PCI in India is influenced by geographical factors such as latitude, longitude, and elevation. Significant increasing and decreasing trends in annual PCI have been observed in the northeast, eastern, and western coasts of India, respectively. Gridded data intercomparison suggests that the gauge‐based APHRODITE, GPCC, and satellite‐derived CHIRPS datasets better perform in capturing the temporal and spatial variation of PCI across India when compared to the IMD gridded dataset, whereas the ERA‐5 performs better among the reanalysis datasets. However, the rainfall datasets exhibited marked differences with the IMD while estimating the annual and seasonal trend and its magnitude across various regions of India. The JRA‐55 overestimated areas of positive trend and its magnitude on annual and seasonal scale. These findings have practical implications for hydroclimatic studies. [ABSTRACT FROM AUTHOR]

One of the most relevant and debated topics related to the effects of the climate change is whether intense rainfall events have become more frequent over the last decades. It is a crucial aspect, since an increase in the magnitude and frequency of occurrence of heavy rainfall events could result in a dramatic growth of floods and, in turn, human lives losses and economic damages. Because of its central position in the Mediterranean area, Sicily has been often screened with the aim to capture some trends in precipitation, potentially related to climate change. While Mann‐Kendall test has been largely used for the rainfall trend detection, in this work a different procedure is considered. Precipitation trends are here investigated by processing the whole rainfall time‐series, provided by the regional agency SIAS at a 10‐min resolution, through the quantile regression method by aggregating precipitation across a wide spectrum of durations and considering different quantiles. Results show that many rain gauges are characterized by an increasing trend in sub‐hourly precipitation intensity, especially at the highest quantiles, thus suggesting that, from 2002 to 2019, sub‐hourly events have become more intense in most of the island. Moreover, by analysing some spatial patterns, it has been revealed that the south and the east of Sicily are more interested in significant increasing rainfall trends, especially at the 10‐min duration. Finally, the comparison between the two procedures revealed a stronger reliability of the quantile regression in the trend analysis detection, mainly due to the possibility of investigating the temporal variation of the tails of precipitation distribution. [ABSTRACT FROM AUTHOR]

Extreme cold events ("cold waves") have disastrous impacts on ecosystem and human health. Evidence shows that these events will still occur under current increasing mean temperatures. Little research has been done on extreme cold events, especially in developing countries such as South Africa. These events pose a significant threat due to the low adaptive capacity, urgent development needs and relatively inadequate infrastructure in South Africa. This study presents annual and seasonal, spatial and temporal trend analyses of extreme cold temperature events for the period 1960–2016. We apply the World Meteorological Organisation Commission for Climatology and Indices Expert Team on Sector‐Specific Climate Indices (ET‐SCI) to South Africa for the first time, with comparison to the World Meteorological Organisation Expert Team on Climate Change Detection (ETCCDI) indices previously used in South Africa. The extreme cold indices are calculated using the RClimDex and ClimPACT, respectively. Trends were calculated using the non‐parametric Mann‐Kendall test, Spearman Rank Correlation Coefficient and Sen's slope estimates. A decreasing trend is found for annual cold spell duration and cold wave frequency, at rates of 0.10 days.day−1 and 0.02 events.day−1, respectively. Seasonally, coldest day temperatures increased in autumn, with increases of 0.02°C.day−1 for the period 1960–2016. Regionally, increasing trends in annual cold spell duration days were evident in stations located in the Western Cape, Eastern Cape, North‐West Province, at a rate of 0.03 days.day−1. Increasing trends in cold waves were observed for stations in Northern Cape, Gauteng, KwaZulu‐Natal and the Eastern Cape Province, at a rate of 0.01 events.day−1. These results contribute to the awareness and recognition of the incidence and duration of cold extreme events in South Africa, seeing that studies suggest that anomalously cold events may persist in a warming world. [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]

Rainfall trend analysis provides useful information for effective planning, and management of water resources, and gives an insight into climate change of a region. This study investigates trends in annual and seasonal rainfall over Sri Lanka using an Innovative Trend Analysis (ITA) and Mann–Kendall (MK) test with Sen's slope estimator. The MK test showed increasing trends in annual rainfall at 24 stations (65%) with five stations showing significant increasing trend. Annual rainfall at 13 locations (35%) showed decreasing trend, but none were significant (p <.05). ITA results for annual rainfall showed increasing trend at 67% stations while 33% stations showed decreasing trend. MK test results for seasonal rainfall indicated increasing trend at 76, 51, 32, and 86% of stations during First Inter‐Monsoon (FIM), Second Inter‐Monsoon (SIM), South West Monsoon (SWM), and North East Monsoon (NEM) seasons, respectively. Seasonal analysis of rainfall trend using ITA method showed increasing trend in 81, 70, 32, and 65% stations during FIM, SIM, SWM, and NEM, respectively. ITA and MK tests exhibited similar trend results for 80% of the stations. Moreover, Spearman's rho correlation coefficient between ITA and MK test trends showed significant (p <.05) positive correlation. In general, eastern, south eastern, north and north central regions of the country showed increasing rainfall trend over the last 31 years (1987–2017) while western, part of north western and central part of the country indicated a decreasing rainfall trend during the same period. [ABSTRACT FROM AUTHOR]

This study uses the daily maximum and minimum temperature data sets of 48 meteorological stations to assess the observed changes in temperature extremes over China–Pakistan Economic Corridor (CPEC) during 1980–2016. The nonparametric Mann–Kendall, Sen's slope estimator, least squares method, and two‐tailed simple t‐test methods were used to assess the trend in nine temperature extreme indices. The results of the study indicated that the trends in annual mean anomalies of cold nights, cold days, and frost days significantly decreased at the rates of −1.09, −1.58, and −1.05 day/decade, respectively. The number of warm nights, warm days, and summer days exhibited significant positive trends at the rates of 1.49, 1.04, and 4.32 day/decade, respectively. In addition, the trends of the warmest day and coldest day also increased significantly at the rates of 0.45 and 0.51 °C/decade, respectively. The trend of diurnal temperature range decreased significantly with −0.35 °C/decade. The spatial distribution of temperature extreme indices indicated that the number of cold nights, cold days, and diurnal temperature range have been decreased, while the trends of warm nights, warm days, summer days, warmest day, and coldest day have been increased over the whole country. Large‐scale atmospheric circulation changes derived from ERA‐Interim reanalysis show that a weak (strong) wind pressure, increasing (decreasing) geopotential height, and rapid warming (cooling) over the northern (southern) region have contributed to the changes in temperature extremes in Pakistan to some extent. With respect to elevation‐dependent warming (EDW), the trends of cold nights, warm days, summer days, warmest day, and diurnal temperature range showed significant positive correlations with increasing elevation. However, the trends of cold days, warm nights, frost days, and coldest day showed significant negative relationships with increasing elevation. The findings of this study will be helpful in the adaptation of climate change and mitigation of climatological disasters in the region. The study recommends that future studies should investigate the natural and anthropogenic drivers of temperature extremes and the possible mechanism of EDW in the CPEC region. Topographic map of the study area with CPEC routes and selected meteorological stations. [ABSTRACT FROM AUTHOR]

This paper examines changes in rainfall in New South Wales (NSW), Australia using daily rainfall data from 200 rainfall stations covering the period of 1945–2014. The Mann–Kendall test is applied to identify trends in the selected rainfall indices, while the Pettitt change point test is employed to determine the direction and timing of a change point. Van Bell and Hughes homogeneity test is applied to examine homogeneity of the observed trends. It is found that the southern half of NSW is dominated by a negative trend in annual total rainfall, and autumn and spring rainfall. Based on the Pettitt change point test, it is found that annual maximum 24-h rainfall data in NSW is dominated by a negative shift. Based on the Van Belle and Hughes method, it is found that NSW is dominated by non-homogeneous trends in monthly maximum daily rainfall data. Overall, the results do not show any consistent pattern of rainfall trends in NSW. The findings of this study contribute towards the growing body of knowledge on the nature of changes in rainfall based on the latest data in NSW. [ABSTRACT FROM AUTHOR]

ABSTRACT: This study examines the spatial and temporal surface (10 m) wind speed trend characteristics of Brazil during 1980–2014 using two in situ and three climate reanalysis datasets. Nonparametric regression is used to understand how mean seasonal and annual wind speeds change over space and time across Brazil. Overall temporal linear trends show that station and reanalysis products exhibit varying seasonal and annual wind speed trends. A geographic examination displays statistically significant (P < 0.05) positive (negative) mean wind speed trends for equatorial (southeastern and central) Brazil. Quantile regression is performed to interpret how wind speed changed across different percentiles. Results show that the largest positive and negative spatial wind speed trends occur for the upper percentiles (75 and 95%). The spatial and temporal trends and correlations described could be interconnected to possible changes developing with the location of Intertropical Convergence Zone and South Atlantic Anticyclone over the study region. Results have implications for optimizing renewable wind energy production and development across Brazil. [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]

ABSTRACT Snowfall in mountainous areas provides indispensable water sources for arid and semi-arid watersheds. Changes in snowfall and snowmelt regimes have significantly impacted the water resources' variations and management. This study addresses the ratio of snowfall to precipitation (S/P) in the Tian Shan Mountains, China. It aims to examine changes in S/P ratio and its synchronization with climate change. The results show that the average S/P ratio experienced a downward trend under the precipitation and snowfall increases as well as temperature increases during the cold seasons in 1961-2010. Spatially, the S/P ratios show an increasing trend in the Boertala Valley and the southern slope of the middle Tian Shan Mountains, but a decreasing trend in Yili Valley, and the western and the northern slope of the middle Tian Shan Mountains. The S/P ratios decreased significantly in middle altitudes with elevation ranging from 1500 to 2500 m, but either decreased or increased at elevations below 1500 m due to a temperature inversion in the elevation belt. In high altitudes with elevation over 3500 m, the magnitudes of the decreased S/P ratios were small because the temperature was always below freezing. The decreases in S/P ratio was mainly attributed to the relative changes in snowfall (dS/S) being less than that in precipitation (dP/P), whereas the increases in S/P ratio resulted from the relative changes in snowfall (dS/S) being more than that in precipitation (dP/P). Temperature increases have also lead to the decreases in S/P ratios to some extent. [ABSTRACT FROM AUTHOR]

ABSTRACT In this study, a comprehensive analysis of long-term trends of the Koshava wind during the period between 1949 and 2010 is carried out. Koshava is a strong wind that blows from southeast quadrant over Serbia, Bulgaria and Romania. The Siberian high and West-Mediterranean cyclones, together with the orography of the eastern Balkan, are the main drivers of the Koshava wind. The trend analyses are performed on wind data sets from five synoptic weather stations, all situated in the region where the Koshava wind is fully developed. Koshava wind speeds are divided into two categories: (1) all wind speeds and (2) wind speeds above 5 ms−1. Two homogeneity tests are used to inspect the quality of wind speed and wind direction time series. The Mann-Kendall test and Sen's slope estimator are used to analyze trends of the Koshava wind speeds and the annual number of days with the Koshava wind. Statistically significant negative trends of the Koshava wind speeds and wind activity are observed at all five weather stations and are more pronounced for wind speeds above 5 ms−1. The negative trends of the Koshava wind are mostly related to the changes in the synoptic circulation, temperature and weakening of the Siberian high and West-Mediterranean cyclones. It is shown that the observed decline of the Koshava wind has a significant impact on reducing the wind energy potential in the region. [ABSTRACT FROM AUTHOR]

ABSTRACT The daily snow cover data from Interactive Multisensor Snow and Ice Mapping System ( IMS) by National Oceanic and Atmospheric Administration's National Environmental Satellite Data and Information Service ( NOAA/ NESDIS) covering the 2004-2012 time period is used in this study. In the first part of the study, daily IMS product is validated over Turkey using daily ground truth snow depth measurements from 219 climatological and synoptic sites. The categorical statistics of probability of detection ( POD) and false alarm rates ( FAR) are provided both for whole Turkey and with respect to geographical sub-regions. The overall POD and FAR amounts for Turkey are obtained as 73.55 and 25.11%, respectively. The performed analysis indicates an increase in IMS accuracies as the snowpack depth at the stations increase. In the second part of the study, the nonparametric Mann-Kendall test is performed to analyse the snow cover trend over Turkey with respect to sub-regions considering the whole year and each season separately. A negative trend in snow-covered area percentage is obtained for Turkey at the significance level of α = 0.05. From the seasonal perspective for Turkey, negative trend for spring and summer seasons, positive trend for autumn season and combination of negative and no trend for winter season are obtained at the same significance level. Almost the same results are valid for the sub-regions with some local and seasonal variations. [ABSTRACT FROM AUTHOR]

ABSTRACT There is little dispute that global surface air temperature has increased and the anthropogenic-induced global warming is likely to play an important role in the management of water resources of a river basin. Therefore, this study was undertaken for Godavari River basin, a large southern peninsular river basin in India. After removing the effect of significant lag-1 serial correlation by pre-whitening procedure, the Mann-Kendall ( MK) test was employed to investigate trends in maximum temperature ( Tmax), minimum temperature ( Tmin) and mean temperature ( Tmean) at 35 stations in the basin. At seasonal (monthly) time scales, a majority of the stations exhibited no trends in Tmean, Tmax and Tmin in any of the four seasons (12 months) with the exception of post-monsoon (December) for Tmax and monsoon (July and September) for Tmin. About 60% (45%) of the stations exhibited increasing trends in Tmax ( Tmin) in different durations: the month of December and post-monsoon season (the months of July and September and monsoon season) indicating the presence of an element of seasonal cycle in temperature over the Godavari basin. Results of tests of spatial and temporal homogeneity of trends by the Van Belle and Hughes method showed that trends in temperature over the Godavari basin were not homogeneous for different months or at different stations. In spite of the warmer climate in the basin, the evaporation (Epan) has been found to decrease significantly over the Godavari basin. Strong decreases in wind speed and increases in relative humidity may have actually caused the Epan decreases over the southern peninsular region of India. [ABSTRACT FROM AUTHOR]

ABSTRACT Variability and trends in daily and monthly near-surface temperatures in Uganda, collected over the period 1960-2008 (49 years), are analysed. For this purpose, daily observational maximum and minimum temperature records from eight selected stations in Uganda were acquired from the Uganda Meteorological Department ( UMD). Data collected by the UMD are quality controlled through a rigorous process before being archived. The data received were tested for homogeneity, gaps were filled and correlation analyses were used for validation of area average series. Statistical techniques (e.g. Mann-Kendall and Linear Regression) were employed to analyse temperature variability and to obtain temperature trends. Findings indicate that intra-annual temperature shows reduced variability over recent decades, but which is not statistically significant. Results also demonstrated that maximum temperatures are more variable compared to minimum temperatures in Uganda. An increasing trend in hot days, hot nights, warm nights and warm spells were also detected. At seven of the stations, annual temperature range and diurnal temperature range trends were found to be negative. The finding that intra-annual and intra-monthly variance is declining suggests that fewer anomalously extreme temperature episodes occur. The gap between maximum and minimum extremes is reducing, which supports the observation that minimum temperatures are on the increase. [ABSTRACT FROM AUTHOR]

ABSTRACT We examined trends in minimum and maximum temperatures in the Oahu during the period of past 39 (1969-2007) and 25 (1983-2007) years. We found a strong spatial and temporal variability in the temperature trends on Oahu. During the past 39 years, island-wide minimum temperature has increased by 0.17 °C/decade and shows a considerable variability in trends at individual location. There was no detectable trend found in maximum temperature over the same time period. The year 1983 was identified as the change point in the island-wide minimum temperature. During the recent 25 years annual and summer maximum temperature showed a decline while minimum temperature continued to increase. Trend in diurnal temperature range ( DTR) shows a decline during the past 39 years with a stronger decreasing trend during the recent 25 years. The trend in DTR for Oahu is much higher compared to the global DTR trend indicating a rapid warming in minimum temperature. Extreme temperature indices show a general warming during the past 39 years. There has been significant increase in tropical and warm nights at the two urban stations. Maximum temperature generally followed the Pacific Decadal Oscillation ( PDO) except the period when there is an increase in Hawaii Rainfall Index ( HRI). In contrast, minimum temperature showed better agreement with HRI compared to the PDO, at least up until 1999 after which it showed an increase. Despite the relative cooling in PDO during the recent decade an increase in minimum temperature can be attributed to a decline in HRI. [ABSTRACT FROM AUTHOR]

Seasonal changes of extreme daily temperature indices (frequency of frost days, tropical nights, and 'summer' days) of 25 stations in the Iberian Peninsula (IP) from 1929 to 2005 are investigated. Cluster analysis is used to identify homogeneous groups of stations with similar thermal regimes. The Mann-Kendall test is applied to look for statistically significant trends. The results show a significant decreasing trend (−0.6 days/decade), especially from 1965 onwards, in the frequency of frost days for coastal stations, and significant increasing trends, from 1980 onwards, especially important to the southeast of the IP (+3.8 days/decade) for summer tropical nights, and in the southern stations (+2.3 days/decade) for summer days. The behaviour of the winter frost days index is related to the evolution of winter NAO and EA patterns (with increasing trends in the last decades of the 20th century). Although multiple regression models establish a relationship between summer indices and the SCAN pattern, the behaviour of residuals indicates that summer indices must be explained by other causal mechanisms. Copyright © 2011 Royal Meteorological Society [ABSTRACT FROM AUTHOR]

This study examines the climatology of annual frost days, and analyses the size and behaviour of the long-term variability and trends in annual numbers of frost day at the 72 stations over Turkey from 1950 to 2010. The main results are summarized as follows: (1) The annual number of frost days has evidently decreased at most of the stations with some observed regional differences, (2) The decreasing trends are largest over the Eastern Anatolia, the Marmara regions and along the Mediterranean coastline. The meteorological stations located in the continental northeast and the easternmost parts of the Anatolian Peninsula, including Ardahan, Iǧdır and Van, show a negative linear trend with a rate of four days per decade, (3) As in other regions of the Earth, changes in number of frost days are very likely associated with changes in minimum air temperatures and increasing growing season lengths in Turkey, (4) The decreasing trends in number of frost days also indicated considerable decadal-scale variability. This variability is very likely attributable to the large-scale atmospheric circulation and atmospheric oscillations such as the Arctic Oscillation (AO) or North Atlantic Oscillation (NAO) and the North Sea-Caspian Pattern, (5) Consequently, the long-winter (DJFM) composites of number of frost days were examined for extreme phases of the AO index during the period 1950-2010 in order to assess the influence of atmospheric oscillations on year-to-year variability in number of frost days. According to the Cramer's t k test, winter number of frost days tended to increase significantly during the high (positive) index AO phase, while they tended to decrease significantly during the low (negative) index AO phase. These relationships are statistically significant at the 1% level at the majority of stations. Copyright © 2011 Royal Meteorological Society [ABSTRACT FROM AUTHOR]

The interannual variability of rainfall amounts and rainy days is analysed from synoptic stations located in different climatic zones of Congo-Brazzaville over the common period 1932-2007. The annual and seasonal rainfall evolution is appreciated using standardized indices. Trends examined were based on the non-parametric Mann-Kendall test (the major synoptic stations point out alternative periods of anomalies-positive and negative). A majority of negative anomalies is recorded during the 1930s and 1940s. The decade 1950 shows mainly positive anomalies with the exception of 1958 which records a general precipitation deficit all across Congo. The decade 1960 is characterized by precipitation excess over the whole Congo. The decades 1980 and 1990 experience the largest rainfall deficit (about 10-20% below the long-term mean). The evolution of the precipitation at Brazzaville is particularly stable, although there are large positive anomalies during the 1990s. The transition between positive and negative anomalies decades is not uniform across Congo. The progressive non-parametric Mann-Kendall trend test shows that there is stability in the annual rainfall and rainy days over the southern area in the period 1932-2007. By contrast, the annual rainfall for the northern stations shows a significant decline since about the 1980s. In the south the decline is observable only in the evolution of the March-May seasonal rainfall. In most of the stations there is a precipitation increase during the September-November rainy season. Copyright © 2011 Royal Meteorological Society [ABSTRACT FROM AUTHOR]

The article discusses research on the consideration of spatial and temporal variations to analyze changes and trends of precipitation total series from 97 stations in Turkey. It says that secular trends in precipitation series were examined using the Mann-Kendall rank correlation test for the general period 1930-2002. In addition, the precipitation series' spatial variabilities and relationships at 86 stations were studied through the principal component analysis (PCA) for the period 1953-2002.

The article presents a study on the hydrological and meteorological change in the Yangtze River Basin in China. Significant changes were found in many monthly precipitation datasets that were collected between 1961 and 2000. It states that the strongest relative increase was detected when the monthly precipitation is low in absolute terms. Some of the changes in the monthly precipitation in spring and summer from April to August, tends to aggravate the flood hazard. It also detected significant upward trends in the discharge of the River Yangtze Basin in the middle and lower regions on summer months.

The article offers information on the climactic effects of urbanization in Istanbul, Turkey, using statistical and modeling method. To capture the climactic trends and changes in trends in Istanbul, the Mann-Kendall trend test and a mesoscale atmospheric model were used. The study shows the expansion of urban heat in the city is related to population growth. The experiment recorded the decreasing volume of northeasterly wind and water vapor mixing over the city. The increasing heat in the city is associated on the urbanization activity in earth's surface.

The article presents an analysis of the trends in daily rainfall in the Iberian Peninsula from 1951 to 2002. It examines the annual and seasonal variations in total precipitation, precipitation intensity, number of wet days, and percentage of rain falling on days above the 95th percentile from daily precipitation records in 22 sites. Results of the study show a decrease in the daily intensity of rainfall and a decreasing trend in precipitation intensity in winter and annual series for some localities.