大气科学2018，Vol.42Issue(2)：339-356,18.DOI:10.3878/j.issn.1006-9895.1712.17126
一次飑线过程对流稳定度演变的诊断分析
Diagnostic Analysis of Convective Stability Evolution during a Squall Line Process
摘要
Abstract
The Weather Research and Forecast (WRF) model with a high resolution is used to simulate the rainfall during a squall line process that occurred in eastern China on 2 May 2016. Based on the successful simulation of the squall line process including its formation, strengthening, and evolution, the convective instability characteristics and the causes of the convective stability variation are analyzed. The results are as follows. (1) Before the rainfall occurrence, the atmosphere was convectively unstable; after the rainfall occurred, however, the atmosphere tended to be stable due to the release of unstable convective energy. In order to explore the physical cause of the convective stability, the tendency equation of vertical potential temperature gradient in a local rectangular coordinate system is deduced and the potential divergence is the major forcing term in the equation. In the weak rainfall area, the potential divergence in the lower atmosphere was negative, which was conductive to enhanced potential instability. In the strong precipitation area, the potential divergence was positive and tended to inhibit the potential instability. In the lower levels of rainfall area, the main component of the potential divergence was the vertical wind shear item, which represented the joint effects of the vertical wind shear and the atmospheric moist baroclinicity. While in the higher levels, the main component was the divergence item, which reflected the coupling effects of horizontal divergence and potential stability. (2) Since the potential divergence can well represent the effects of vertical wind shear, atmospheric baroclinicity, horizontal divergence, and the variation of atmospheric potential stability, it is used to forecast precipitation during the squall line process in the present study. Results show that the spatial and temporal distribution of potential divergence is in good agreement with that of observed hourly precipitation. Therefore, the potential divergence is indicative of rainfall area and can provide an important reference for operational precipitation forecast during squall line processes.关键词
飑线/对流不稳定/位势稳定度/位势散度Key words
Squall/Convective instability/Potential stability/Potential divergence分类
天文与地球科学引用本文复制引用
周围,包云轩,冉令坤,王勇..一次飑线过程对流稳定度演变的诊断分析[J].大气科学,2018,42(2):339-356,18.基金项目
公益性行业(气象)科研专项GYHY201406029、GYHY201306043,国家重点基础研究发展计划项目2013CB430105,国家自然科学基金项目41175060,Special Scientific Research Fund of Meteorological Public Welfare Profession of China (Grants GYHY201406029, GYHY201306043), National Basic Research Program of China (Grant 2013CB430105), National Natural Science Foundation of China (Grant 41175060) （气象）
