利用常规资料作飑线分析的尝试

ANALYSIS OF SQUALL LINE BASED ON CONVENTIONAL DATA

摘要:

本文在珠江流域常规地面站网的自记资料基础上,对1980年2月27日的飑线过程作了详细的分析,发现这是一次锋上的飑线过程。而且,飑线经过测站的时间与测站的日最大风速出现时间很一致。利用这种关系,在1980—1985年2月到6月中辨认出17个飑线个例,对其中一类飑线的大尺度背景进行分析.发现这类以大约70kmh^-1。的速度沿珠江流域东移的飑线是影响广东主要的中尺度强对流天气系统之一,它们属槽前型飑线,其发生往往同地面锋和低空偏南急流相联系。

Abstract:

In this paper, a meso-scale analysis on a squall line process which swept Guangdong Province is operated mainly by utilizing self-recording data of the conventional surface observation network over Pearl River Basin. After surveying its orientatation, movements and the characteristic fluctuation of various meteorological elements during the passage of the squall line, it is concluded that this is a cold frontal squall line process. Based on the correlation between the daily maximum wind(V_M) occurrence time and the squall line passage, under some restrictive conditions, a few squall line activity days can be identified from historical data. The isochrones of V_M can be used to represent the appro ximate positions of the squall line. By analyzing their background fields, it is seen that all the six cases of squall line which moved eastward along Pearl River Basin initiated in front of an upper trough in the subtropical westerlies and most of them were associated with a surface front and low level southwesterly jet. The necessary instable stratifications resulted from the joint effects of lower tropospheric warm moist advection and mid-tropospheric cold advection. The propagating speed of squall lines were nearly equal to the 700 hPa average wind speed at Wuzhou and Guangzhou.