Abstract:

To further understand the climate change in alpine pastoral areas, based on the daily precipitation data of Haiyan Station in the northeast of Qinghai Lake from 1976 to 2017, we determined the extreme precipitation (snow) threshold in winter (summer) half year and counted extreme precipitation events by using the percentile method, analyzed the variation characteristics, future trends and cycles of extreme precipitation events by linear trend, R/S and wavelet analysis. The results showed that: the extreme precipitation days and extreme precipitation in the northeastern of Qinghai Lake did not increase significantly in winter and summer half year; the extreme precipitation intensity and daily maximum precipitation did not increase significantly in winter half year, but did not decrease significantly in summer half year; the contribution rate of extreme precipitation to annual precipitation increased at different rates, and the extreme precipitation in summer half year had a greater impact on annual precipitation; the number of precipitation days in winter half year did not decrease significantly, while the precipitation increased significantly, indicating that the probability of short-term heavy precipitation in winter half year increased, and the number of precipitation days and precipitation in summer half year were not obvious; in the future, the trend of increasing the number of extreme precipitation days in winter half year would change; the extreme precipitation would continue to show volatility irrespective of the previous trend, and other factors would continue to change in the early stage; the number of extreme precipitation days and precipitation in winter (summer) half year had obvious periodic variation characteristics. The study of extreme precipitation in alpine pastoral areas is of significance in preventing the occurrence of snowstorms and floods caused by short-term heavy precipitation.

Key words: extreme precipitation, precipitation intensity, contribution rate, trend