Characteristics of extreme precipitation in Ansai District of Yan'an City, China.

Abstract

The extreme precipitation characteristics of Ansai District in 40 years was analyzed from the perspective of precipitation intensity and precipitation frequency with 11 extreme precipitation indices, based on daily precipitation data of Ansai Meteorological Station from 1980 to 2019. The trend of extreme precipitation in the future was predicted. The results showed that the extreme precipitation indicators generally showed a downward trend during 1980-2019. The downtrend of heavy precipitation days and simple daily precipitation intensity reached significant level, with their climate tendency slopes being -0.65 d·(10 a)-1, -0.32 mm·d-1·(10 a)-1, respectively. Except for consecutive wet days and extremely wet day precipitation, the other extreme precipitation indices had mutation points. After the mutation, most of them had a downward trend, with significant decreases of annual precipitation, moderate precipitation days, heavy precipitation days, very heavy precipitation days, very wet day precipitation, simple daily precipitation intensity. The correlation between the consecutive dry days and other indicators was low and negatively correlated with some indicators, while the consecutive wet days were only correlated with a few indicators. In addition, other extreme precipitation indicators were significantly correlated. Results of the Hurst index analysis showed that the trend of extreme precipitation in Ansai District was sustainable.