Diurnal Variation Of Warm Season Precipitation In Liaoning Province Based On Hourly Data

The study of the diurnal variations of precipitation not only helps to understand the mechanism of precipitation formation and regional climate formation,but also helps to verify the rationality of physical processes in numerical models.Based on the hourly precipitation data from 60 national meteorological stations in Liaoning Province during 2008-2017,the diurnal variations of precipitation amount,precipitation frequency and precipitation intensity of warm season?May-September?precipitation in Liaoning Province were analyzed.The results show that:?1?Daily peaks of precipitation amount and precipitation frequency in Liaoning Province decreased gradually from east to west,while the high peaks of precipitation intensity occurred at the junction of mountains and plains;the diurnal variations of warm season precipitation amount and precipitation frequency in Liaoning Province presented two peaks that occurred in the early morning and late afternoon.The peaks of precipitation amount in the early morning and late afternoon were roughly equal,and the peak of precipitation frequency in the early morning was higher than that in late afternoon.The precipitation intensity had an obvious peak in late afternoon.?2?The rainfall diurnal variations in Liaoning Province presented distinct regional features.The diurnal variations of hourly precipitation amount and precipitation frequency in western and central inland presented two peaks that occurred in the early morning and late afternoon,and the diurnal variation of precipitation intensity had an obvious peak in late afternoon.But the peaks of hourly precipitation amount,precipitation frequency and precipitation intensity in the western were smaller than those in the central inland.The diurnal variations of hourly precipitation amount and precipitation frequency in central coastal and eastern presented a single peak that occurred in the early morning,but the peaks of precipitation amount and precipitation frequency in the central coastal were smaller than those in the eastern.?3?The contribution of long-duration precipitation??7h?to the warm season daily precipitation was greater than that of short-duration precipitation?1³h?in Liaoning Province.Long-duration precipitation had a greater contribution to the peak of precipitation amount in the early morning,while short-duration precipitation had a greater contribution to the peak of precipitation amount in the late afternoon.The peaks of precipitation in late afternoon in western and central inland were dominated by 1⁶h precipitation.The peak of precipitation amount in the early morning in western was dominated by long-duration precipitation?? 7h?,while the peaks of precipitation amount in the early morning in central inland,central coastal and eastern were dominated by the duration precipitation of greater than 3 hours.?4?L1 level(0.1¹0mmh^-1)precipitation contributed most to the warm season total daily precipitation and dominated the diurnal variation of hourly precipitation amount.The precipitation amount and precipitation frequency of L2(10.1²5mmh^-1)and L3(25.1⁵0mmh^-1)in sub-regions had multi peaks.The mainly peaks of precipitation amount and precipitation frequency in western and central inland occurred in late afternoon,while the mainly peaks in central coastal and eastern occurred in the early morning.