Abstract:
Based on 20-08,20-20 precipitation data from May to September in 1961-2018,and hourly precipitation data from 2010 to 2018,the spatiotemporal variations such as the rate,intensity and frequency of night precipitation in Sichuan Basin are analyzed by using the EOF and other methods.The results show that:(1)The night precipitation rate reveals a consistent variational feature in Sichuan Basin from the EOF first eigenvector,which accounts for 17.1% of the total variance.And the EOF first eigenvector(21.5%)of night precipitation intensity reveals a meridional dipole spatial distribution with 105.5 ° E as the boundary.(2)The high frequency center of night precipitation is located at the junction of Ya'an,Leshan and Meishan.The sub-high frequency regions are in the southwest and south of Sichuan Basin as well as along the west mountains,while the middle and northeast of Sichuan Basin are the lower frequency areas.In addition,the frequency of precipitation characterized in a single peak time from 02 to 05.(3)From light rain to heavy rain,the daily and monthly variation of night precipitation rate and intensity show that:the night precipitation rate first decreases and then rises,while the intensity first rises and then decreases,with transitional period from July to August.In addition,the annual variation shows a wave-like distribution,without obvious upward and downward trend.