Impact of daytime precipitation duration on urban heat island intensity over Beijing city

This study used the daytime hourly precipitation records and divided them into four types of duration to examine the impact of different daytime precipitation conditions on Urban Heat Island Intensity (UHII) over Beijing city. Results show that the magnitude differences of UHII are in close relation with the length of Continuous Precipitation Hours of Daytime (CPHD). The longer the CPHD, the less obvious the average UHI. When continuous precipitation events dominate the daytime, the diurnal variation pattern of UHII will be changed greatly. There are generally two (strong and weak) stable stages of UHII in no-rainy condition, while it disappears completely in the longest continuous daytime precipitation conditions. However, the diurnal cycles of UHII differences between each of the rainy daytimes and no-rain daytimes appear similar, with all of the dual peaks of the UHII differences occurring around sunrise (0600-0700 LST) and sunset (2000 LST), and the minimum of the UHII differences appearing stably from 1100 to 1500 LST.