Diurnal Variations of Precipitation, Deep Convection, and Lightning over and East of the Eastern Tibetan Plateau

Abstract

Diurnal cycles of total rainfall, precipitation features, mesoscale convective systems (MCSs), deep convection, precipitation vertical structure, and lightning over the eastern Tibetan Plateau (TP) and eastward through China are investigated using 11 yr of Tropical Rainfall Measuring Mission (TRMM) measurements. Diurnal cycles of rainfall and precipitation features present apparent phase propagation eastward from the eastern TP for about 1000 km. The phase propagation is most evident during the pre-mei-yu and mei-yu seasons. However, it weakens with the northward progress of the East Asian monsoon and ceases in midsummer. During the pre-mei-yu season, diurnal cycles of storm population, total rainfall, deep convection, and lightning over the central and eastern TP foothills are in phase, peaking during the early morning. Another striking feature of the pre-mei-yu season is that nocturnal rainfall and MCSs prevail over the southeastern TP foothills following the deep convection and lightning maxima. These nocturnal peaks of deep convection and lightning over the foothills shift to afternoon after the onset of the monsoon, but nocturnal precipitation still dominates. Over the less mountainous region of eastern China, deep convection usually has an afternoon peak during the mei-yu whereas the rainfall maximum is at night. In midsummer, most parts of eastern China have strong afternoon peaks of deep convection, precipitation, and lightning, except in northeastern China where deep convection has an afternoon peak followed by a nocturnal precipitation peak.