A comparative study on frontogenesis characteristics in different phase during an extreme precipitation process
A rainstorm and snowstorm weather occurred in Yunnan from the evening of 8 to 10 January 2015, which was the most extreme precipitation process in January since 1961. Based on NCEP/NCAR reanalysis data, frontogenetic function and characteristics of front secondary circulation in different phase were diagnosed. Furthermore, the production mechanism of strong rain and snow was discussed. It was showed that the water vapor transport from Bay of Bengal to South Yunnan deviating from climatological mean degree reached 3σ, center intensity of frontal zone in South Yunnan was-5 × 10-5 K·m-1, namely anomaly cold and warm airflow intersected in Yunnan, which made this strong rain and snow weather. Furthmore, frontogenesis function analysis showed that at the prophase of heavy rain, horizontal convergence in lower layer and ascending motion aggravated, which made precipitation reach peak. Thereafter, horizontal deformation field, especially shear deformation's increasing made frontogenetic function maintain, but strength was obviously weak. For the snowstorm, the first peak formation of snowfall was mainly inclined item function, while the second, they were horizontal deformation and inclined items' functions, among horizontal deformation item, it was mostly growth of elongation deformation. In addition, strongly as cending motion in front secondary circulation's ascending branch provided favorably dynamic condition to strong rain and snow weather.
NETL
NSTL
万方数据
维普
