Trend analysis of extreme precipitation indices in Lake Urmia basin and their relation with Teleconnection patterns

One of the most important effects of climate change is increasing in extreme climate events. Change in the frequency or intensity of extreme events can have significant impacts on natural environments and human societies so their analysis is very important. The aim of this study is to identify the trend of precipitation extremes in Lake Urmia basin and to investigate their relation with Teleconnection patterns. For this purpose, daily precipitation data of 7 synoptic stations in the basin during 1987-2014 was used. 11 extreme precipitation indices were extracted using the RClimDex and their trends were calculated by non-parametric Mann-Kendall test. Then the relationship between these indices with Teleconnection patterns was determined by the Pearson correlation coefficient. The results of time series analysis showed that all extreme precipitation indices in Lake Urmia basin have decreasing trend exept consecutive dry days (CDD). The spatial distribution of trend in extreme indices showed almost all indices have a significant trend at the 5% significance level in basin. There is no significant trend in consecutive dry days (CDD). The changes in extreme precipitation could be affected by the El Niño-Southern Oscillation (ENSO), Southern Oscillation Index (SOI), East Pacific-North Pacific (EP-NP), Madden and Julian Oscillation (MJO) and Pacific Decadal Oscillation (PDO).