Journal ArticleDOI
Changes of Pan Evaporation in the West of Iran
Hossein Tabari,Safar Marofi +1 more
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In this article, the authors investigate temporal variations in pan evaporation and the associated changes in maximum (Tmax), mean (Tmean) and minimum (Tmin) air temperatures and precipitation (P) for 12 stations in Hamedan province in western Iran for the period 1982-2003.Abstract:
Evaporation is an important component of the hydrological cycle and its change would be of great significance for water resources planning, irrigation control and agricultural production. The main purpose of this study was to investigate temporal variations in pan evaporation (Epan) and the associated changes in maximum (Tmax), mean (Tmean) and minimum (Tmin) air temperatures and precipitation (P) for 12 stations in Hamedan province in western Iran for the period 1982–2003. Significant trends were identified using the Mann–Kendall test, the Sen’s slope estimator and the linear regression. Analysis of the Epan data revealed a significant increasing trend in 67% of the stations at the 95% and 99% confidence levels. To put the changes in perspective, the trend in Epan averaged over all 12 stations was (+)160 mm per decade. Trend analysis of the meteorological variables for examination of causal mechanisms for Epan changes showed warming trends in Tmax, Tmean and Tmin series in almost all the stations, which were significant over half of the total stations. On the contrary, no significant changes in precipitation were found approximately at all of the stations. Furthermore, a moderate positive correlation was observed between Epan and Tmax, Tmean and Tmin, while a inverse correlation was found between Epan and P data. The results indicated that the study area has become warmer and drier over the last 22 years, hence the evaporative demands of the atmosphere and thereby crop water requirements have increased.read more
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Analysis of changes in meteorological variables using Mann-Kendall and Sen's slope estimator statistical tests in Serbia
Milan Gocic,Slavisa Trajkovic +1 more
TL;DR: In this article, the authors analyzed the annual and seasonal trends of seven meteorological variables for twelve weather stations in Serbia during 1980-2010 and used the nonparametric Mann-Kendall and Sen's methods to determine whether there was a positive or negative trend in weather data with their statistical significance.
Journal ArticleDOI
Global review and synthesis of trends in observed terrestrial near-surface wind speeds; implications for evaporation
Tim R. McVicar,Michael L. Roderick,Randall J. Donohue,Ling Tao Li,Tom Van Niel,Axel Thomas,Jürgen Grieser,Deepak Jhajharia,Y. Himri,Natalie M. Mahowald,Anna V. Mescherskaya,Andries Kruger,Shafiqur Rehman,Yagob Dinpashoh +13 more
TL;DR: In this paper, the authors present a review of the literature to assess whether stilling is a globally widespread phenomenon and highlight the contribution of the aerodynamic and radiative components to these declining evaporation rates.
Journal ArticleDOI
Temporal variability of precipitation over Iran: 1966-2005
TL;DR: In this paper, the authors analyzed the annual and seasonal precipitation trends of 41 stations in Iran for the period 1966-2005 using the Mann-Kendall test, the Sen's slope estimator and the linear regression.
Journal ArticleDOI
Trend analysis of reference evapotranspiration in the western half of Iran
TL;DR: In this paper, the authors examined the Penman-Monteith ETO at 20 meteorological stations during 1966-2005 in the western half of Iran using the Mann-Kendall test, the Sen's slope estimator and the linear regression.
Journal ArticleDOI
Trends in reference crop evapotranspiration over Iran
Yagob Dinpashoh,Yagob Dinpashoh,Deepak Jhajharia,Ahmad Fakheri-Fard,Vijay P. Singh,Ercan Kahya +5 more
TL;DR: In this article, the authors examined the trends in reference crop evapotranspiration (ET0) on monthly and annual time scales in Iran using the globally accepted FAO Penman Monteith method.
References
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TL;DR: In this article, a simple and robust estimator of regression coefficient β based on Kendall's rank correlation tau is studied, where the point estimator is the median of the set of slopes (Yj - Yi )/(tj-ti ) joining pairs of points with ti ≠ ti.
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The cause of decreased pan evaporation over the past 50 years.
TL;DR: In this article, the authors show that the decrease in evaporation is consistent with what one would expect from the observed large and widespread decreases in sunlight resulting from increasing cloud coverage and aerosol concentration.
Journal ArticleDOI
Trend analysis in Turkish precipitation data
Turgay Partal,Ercan Kahya +1 more
TL;DR: In this article, a trend analysis of the long-term annual mean and monthly total precipitation series using non-parametric methods (i.e., the Mann-Kendall and Sen's T tests) is presented.