Multi-scale interactions between thermal anomalies over the Tibetan Plateau and extreme precipitation in southern China

Multi-scale interactions between thermal anomalies over the Tibetan Plateau and extreme precipitation in southern China

Fei Chen^1,2, Yali Luo¹, Yanhong Gao³, and Guo Zhang¹

¹State Key Laboratory of Severe Weather, Chinese Academy of Meteorological Sciences, Beijing, China

²National Center for Atmospheric Research, Boulder, CO, USA

³Key Laboratory of Land-surface Process and Climate Change in Cold and Arid Regions, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou, China

This paper provides a synopsis of current research on the impact of thermal anomalies over the TP on persistent extreme precipitation events (PEPEs) in southern China. We analyzed 30-year(1981-2010) observations, which indicated an increase of TP surface air temperature 3-4 days prior to PEPEs in southeastern China, accompanied low-pressure anomaly in southern China and a high-pressure anomaly in northern. Using correlation analysis and random resampling nonparametricstatistics, we simulated a typical PEPE event from 17 to 25 June 2010 with the WRF Model to investigate the impact of the TP's surface heating on theevolution of this event. Three contrasting WRF experiments were conducted with different surface heatingstrengths by changing initial soil moisture over the TP. Thermal anomalies over the TP have two main effects on this PEPE event: 1) modulate large-scale atmospheric circulations and modifying the watervapor transport to southern China; and 2) strengthen a high pressure systemover the Yangtze Plain, thereby blocking the northward movement of precipitation. It also enhances the watervapor transport from the South China Sea to southern China. The combined effects substantially increaseprecipitation over most of the southeastern China region. Also, we analyzed the correlation between 24 extreme (for 1998-2015) precipitation events in southern China and wave perturbation at synoptic scales, and found that those main synoptic perturbations originated from southeastern TP. We will discuss those new findings in the context of weather and climate research regarding the role of thermal anomalies in PEPEs in southern China, and future work that need to be pursued to further understand the role of TP thermal anomalies in synoptic temporal and spatial scales.