Subtropical Westerly Jet Waveguide and Winter Persistent Heavy Rainfall in South China
Title: Subtropical Westerly Jet Waveguide and Winter Persistent Heavy Rainfall in South China
Journal:Journal of Geophysical Research: Atmosphere, 122(14), 7385–7400, doi:10.1002/2017JD026530
Authors: DING F., and C. Li*
Abstract: Using observeds daily precipitation and NCEP/NCAR reanalysis data, what induced winter large-spatial persistent heavy rainfall (PHR) events in South China was examined, based on composite analyses of 30 large-spatial PHR events during 1951-2015. The results showed wave trains within North African-Asian (NAA) westerly jet existed in upper troposphere during these PHR processes. The wave trains shared the characteristic of Rossby wave. The Rossby wave originated from the Northwest Europe, and entered into NAA jet through strong cold air advection to form convergence over the Mediterranean, and then propagated eastward along subtropical NAA jet. The Rossby wave propagated toward Southeast Asia and caused strong divergence in the upper troposphere. The strong divergence in the upper troposphere induced vertical convection and favored large-spatial PHR events in South China. In addition, the enhanced India-Burma trough and subtropical high in the Northwestern Pacific supplied enough water vapor transportation. This mechanism would be useful to the medium-range forecast of such winter rainfall processes over South China.