The Relationship between Precipitation and Airflow over the Tibetan Plateau in Boreal Summer
LI Fei 1,2 and FENG Juan 1 1 State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG), Institute of At- mospheric Physics (IAP), Chinese Academy of Sciences, Beijing 100029, China 2 Graduate University of the Chinese Academy of Sciences, Beijing 100049, China
Based on the observation data and the reanalysis datasets, the variability and the circulation features influencing precipitation in the Tibetan Plateau (TP) are investigated. Taking into account the effects of topography, surface winds are deconstructed into flow-around and flow-over components relative to the TP. Climatologically, the flow-around component mainly represents cyclonic circulation in the TP during the summer. The transition zone of total precipitation in the summer parallels the convergence belt between the southerlies and the northerlies of the flow-over component. The leading mode of rainfall anomalies in the TP has a meridional dipole structure, and the first principal component (PC1) mainly depicts the variation of rainfall in the southern TP. The wet southern TP experiences strengthened flow-over, which in turn mechanistically favors intensified ascent forced by the flow-over component. In addition, variations in the Indian summer monsoon (ISM) have an important role in influencing the flow over the southern TP, and the ISM ultimately impacts the precipitation over southern TP.