The effect analysis of three-dimensional divergence and its vertical gradient on convection initiation

Frontiers in Earth Science

Earth Science

Haiwen Liu¹  Lei Chen²  Liqing Tian³  Kuo Zhou⁴  Lingkun Ran⁴  Wancheng Zhang⁵ 

[1] Department of Aviation Meteorology, Civil Aviation University of China, Tianjin, China;Guizhou Meteorological Service Center, Guiyang, China;Hebei Insititute of Meteorological Science, Shijiazhuang, China;Laboratory of Cloud Precipitation Physics and Severe Storms, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China;Yunnan Institute of Meteorological Science, Kunming, China;

关键词: three-dimensional divergence;    pressure;    vertical pressure gradient force;    vertical velocity;    convection initiation;   

DOI  :  10.3389/feart.2023.1143767

 received in 2023-01-13, accepted in 2023-04-11,  发布年份 2023

来源: Frontiers

【 摘 要 】

A severe convection process occurred in southern Xinjiang during June 15–17, 2021. Here, the convection initiation mechanism is revealed by analyzing the impacts of three-dimensional divergence (∇⋅V) on the changes in pressure and the vertical pressure gradient force (VPGF). The pressure tendency equation and vertical pressure gradient force equation are derived based on three-dimensional divergence. It is shown that three-dimensional divergence has a better correlation with precipitation. The local change in pressure is affected mainly by the three-dimensional divergence forcing term. The air mass accumulates in the lower layers because of the three-dimensional convergence in the windward slope, strengthening the positive pressure change tendency. Three-dimensional convergence in the lower layers converts to divergence with height, leading to air mass loss in the upper layers. The air mass redistributes vertically owing to the positive vertical gradient of three-dimensional divergence, which motivates the upward VPGF. The local change in VPGF is highly correlated with the vertical velocity. The vertical velocity increases as the upward VPGF strengthens, resulting in convection initiation in southern Xinjiang.

【 授权许可】

Unknown   
Copyright © 2023 Zhou, Ran, Zhang, Tian, Chen and Liu.