The Role of Shallow Convection over the Tibetan Plateau

Authors:

Yunying Li

School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, New York, and Nanjing University, Nanjing, China

Minghua Zhang

School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, New York, and International Center for Climate and Environment Sciences, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China

Abstract:

Cumulus (Cu) from shallow convection is one of the dominant cloud types over the Tibetan Plateau (TP) in the summer according to CloudSat–CALIPSO observations. Its thermodynamic effects on the atmospheric environment and impacts on the large-scale atmospheric circulation are studied in this paper using the Community Atmospheric Model, version 5.3 (CAM5.3). It is found that the model can reasonably simulate the unique distribution of diabatic heating and Cu over the TP. Shallow convection provides the dominant diabatic heating and drying to the lower and middle atmosphere over the TP. A sensitivity experiment indicates that without Cu over the TP, large-scale condensation and stratiform clouds would increase dramatically, which induces enhanced low-level wind and moisture convergence toward the TP, resulting in significantly enhanced monsoon circulation with remote impact on the areas far beyond the TP. Cu therefore acts as a safety valve to modulate the atmospheric environment that prevents the formation of superclusters of stratiform clouds and precipitation over the TP.

Citation:

Yunying Li, Minghua Zhang: The Role of Shallow Convection over the Tibetan Plateau, Journal of Climate, Volume 30, DOI: 10.1175/JCLI-D-16-0599.1