Torrential Rain in Qinghai Plateau： Forming Conditions and Characteristics

Abstract

This study aims to analyze the forming conditions and characteristics of torrential rain in Qinghai Plateau from 2007 to 2017 based on data from 52 regional automatic weather stations in Qinghai Province， ERA-interim 1°×1° and FY-2 TBB database.The analysis indicates that the Western Pacific subtropical high （hereinafter referred to as the subtropical high） and the Qinhai-Xizang Plateau low vortex shear （hereinafter referred to as the low vortex shear） are the main weather systems that affect the torrential rain in Qinghai Province.Based on the analysis， this study further divides the weather patterns for torrential rain in Qinghai Province into three types： Type of subtropical high border， type of subtropical high control and low vortex shear type.The results suggest that： （1）When the center of South Asia High Pressure is located in the southern part of Qinghai or the northern part of Sichuan， and the west ridge of subtropical high is located at 90°E -100°E and 32°N， it is more likely to produce the subtropical high control and border type torrential rain； When the center of South Asia High Pressure is southward， located in Xizang， it is then conducive to the formation of the low vortex shear type torrential rain.（2） The convective systems that produced the torrential rain mainly includes the mobile convective storms under the influence of the low-level jet stream， the non-mobile convective storms under the control of the subtropical high and the merging of multiple convective storms under the maintenance of the plateau shear line.（3） The water vapor source of the subtropical high control and border type torrential rain mainly comes from the Western Pacific region， while the vortex shear type torrential rain mainly comes from the Bay of Bengal， followed by the mid-latitude westerlies as secondary water vapor sources.（4） The torrential rain on the border of subtropical high has the typical characteristic of frontal precipitation.The rainstorm area appears in the concentrated area of the θse isogram inclined to the north， the mixed precipitation is dominant and the average precipitation duration is 12 h； The subtropical high control type torrential rain occurred in the high temperature and high humidity environment.The precipitation efficiency is high.Convective precipitation is considered to contribute most part of the total precipitation， and the average precipitation duration is 6 h.To some degree， the environment of low vortex shear type torrential rain also has the characteristics of baroclinic front type precipitation， but the θse contour is relatively sparse， and stable precipitation is dominant， the average duration of precipitation reaches 18 h.

Keywords

• qinghai province
• rainstorm
• convection system
• precipitation characteristics