A Heavy Precipitation Event in the Yangtze River Basin Led by an Eastward Moving Tibetan Plateau Cloud System in the Summer of 2016

Abstract

From 29 June to 6 July 2016, China's Yangtze River Basin experienced heavy precipitation, causing more than 200 deaths and affecting tens of millions of people. Using ERA5 reanalysis, soundings, and satellite observations from FY‐2 and Global Precipitation Measurement (GPM), we reviewed this heavy rainfall event from the perspective of its meteorological triggers and the cloud microphysics. As the cloud system moved eastward from the Tibetan Plateau, precipitation particles got larger and denser, and the enhancement of stratiform precipitation contributed the most precipitation. The riming and aggregation processes, the dominant growth modes of particles, were significantly enhanced between 5.5 and 7 km. The increase in the echo‐top height had a considerable positive effect on the near‐surface particle size (from ~1.0 mm at 4 km to ~1.5 mm at 10 km), but this feature was not significant over the Tibetan Plateau. We suggest that the microphysics of this event was dominated by the combination of the eastward moving cloud system, which acted as continuous “seeder” cloud, and the increase in water vapor associated with the low‐level vortex and jet, which generated enhancing “feeder” cloud. The particles from the “seeder” cloud grew by the lower “feeder” cloud, thus increasing the particle size to enhance the precipitation. Overall, the generation and movement of such a cloud system is an important atmospheric disturbance for the generation of heavy precipitation downstream, and could be an early warning signal in the forecasting of heavy rainfall in China during the Meiyu period.

Potential vorticity perspective of the genesis of a Tibetan Plateau vortex in June 2016

“…The occurrence of persistent torrential rain in southern China has long been a key research topic owing to its significant socioeconomic impacts (Tao 1980). Synoptic studies have reached a consensus that the main weather systems that directly contribute to its occurrence come from eastern Asia-namely, cold intrusions from the north, shifts in the Submitted to Climate Dynamics on August 23, 2021. subtropical anticyclone over the northwestern Pacific from the east, monsoon surges from the south, and meso-α lowpressure perturbations from the west via the Tibetan Plateau (TP) (Zhang et al 2002(Zhang et al , 2003Tao and Wei 2007;Chen et al 2020;Wu et al 2020). In addition to these adjacent weather systems, the torrential rainfall over southern China in the summer of 2016 was regulated by the Madden-Julian Oscillation from the tropics (Shao et al 2018) and the atmospheric quasi-biweekly oscillations over the TP (Zhang et al 2021), and attributed to the impacts of the strong 2015/16 El Niño event and external forcing including global warming (Zhou et al 2018).…”

Intercomparison of Cloud Vertical Structures over Four Different Sites of the Eastern Slope of the Tibetan Plateau in Summer Using Ka-Band Millimeter-Wave Radar Measurements

“…However, there is a lack of attention on the cloud vertical structure and diurnal statistical analysis on the eastern slope of the TP (ESTP). Clouds over the ESTP can evolve and eventually form heavy precipitation, which has a profound impact on the Sichuan Basin and the middle reach of the Yangtze River [27]. Geographically, the ESTP is a transitional area between the main body of the TP and the downstream Sichuan Basin.…”

Impacts of land use and land cover change and reforestation on summer rainfall in the Yangtze River basin

“…We are also aware that convective parameterizations differ significantly in their treatment of the cloud updrafts and downdrafts and mass-flux closure and triggering, often assuming that one is averaging over both cloud updrafts and the subsiding environment. As a result, all these schemes are better at predicting the area-average rainfall (Clark et al, 2016). Additionally, the cumulus parameterizations also introduce uncertainties to the model results (Liu et al, 2016).…”