Changes of daily precipitation extremes in the Himalayan range within China, 1978-2016

Abstract

The temporal and spatial changes of trends for extreme precipitation indices were analyzed on account of precipitation records at 9 meteorological stations in Himalayan range within China from 1978 to 2016. The results contain three parts. Firstly, the temporal and spatial changes of trends for precipitation extreme indices are irregular in Himalayan range with China. For regional pattern, only the consecutive dry days (CDD) has a statistically significant increasing trend of 3.17 days/decade over Himalayan range within China. Most of the other indices have statistically significant decreasing trends except CWD and SDII. The regionally averaged consecutive wet day (CWD) is stationary. The regionally averaged simple daily intensity index (SDII) is slightly increasing trend. For individual stations, many stationary trends are observed in heavy, very heavy and extremely heavy precipitation days (R10, R20 and R25). Most of the precipitations on very wet days (R95) have decreasing trends, but they are not statistically significant. Most of the precipitations on extremely wet days (R99) have stationary trends. Increasing and decreasing trends are observed in RX1day, RX5day, SDII and NW. The obvious trends of individual station are detected in PRCPTOT. Secondly, annual total precipitation and precipitation extremes indices have significant correlations based on the methods of Pearson's correlation and two-tailed t-test, except consecutive dry days (CDD). Thirdly, the South Asia Summer Monsoon evolution influence the trend changes of most precipitation extreme indices in the Himalayan range within China.