نتایج جستجو برای: standard precipitation index
تعداد نتایج: 938540 فیلتر نتایج به سال:
Concentrations of chemical constituents of precipitation are frequently expressed in terms of the precipitation-weighted mean, which has several desirable properties. Unfortunately, the weighted mean has no analytical analog of the standard error of the arithmetic mean for use in characterizing its statistical uncertainty. Several approximate expressions have been used previously in the literat...
Drought is a natural and climatic phenomenon that occurs in world wide areas every year and occurrence becomes an inevitable issue. This phenomenon is impaired in ecosystem. Arid rangeland ecosystems are a significant part of our land that is brittle systems that climatic changes are useful to simply unfounded destruction. Therefore, drought identifying and monitoring valid descriptive statisti...
the standardized precipitation index (spi) has become a popular measure of drought across the globe. in this study, standardized precipitation index (spi) was used in annual period of time to survey on drought. also, in order to zonation frequency of drought, geographic information system (gis) software and kriging method used for extracting dry areas. the zoning maps show most severe drought i...
This study aims at predicting the Standard Precipitation Index (SPI) drought class transitions in Portugal, considering the influence of the North Atlantic Oscillation (NAO) as one of the main large-scale atmospheric drivers of precipitation and drought fields across the Western European and Mediterranean areas. Log-linear modeling of the drought class transition probabilities on three temporal...
Drought, which is often defined as not enough precipitation, does a mean simple lack of precipitation. This condition, occurs when humidity less than the average value for many years, caused by disrupted balance between precipitation and evaporation in region. It very difficult to predict start end time drought. In present study, drought conditions stations selected from Yesilirmak Basin 1970 2...
The reliability of standard meteorological drought indices based on measurements of precipitation is limited by the spatial distribution and quality of currently available rainfall data. Furthermore, they reflect only one component of the surface hydrologic cycle, and they cannot readily capture nonprecipitation-based moisture inputs to the land surface system (e.g., irrigation) that may temper...
In the present study, the ARC SWAT model in ARC GIS software was used to model the Zolachai watershed in the city of Salmas (Chehric Alia). For sensitivity analysis, calibration, SPSS statistical software was used. In the model used from precipitation data, minimum temperature, maximum temperature and daily relative humidity of rain gauge and synoptic stations in the study area for 35 years (...
in this research, effect of north atlantic oscillation and sea surface temperature (sst) of atlantic ocean on precipitation and temperature of lorestan province and its effect on occurrence of drought and wet in this province were investigated. so, data of teleconnection indices used as an index for determination of fluctuations of pressure and sea surface temperature in atlantic ocean, amount ...
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