Characteristics of 600 hPa Vortex Activity at Western Sichuan Plateau in Summer Half-Year
- Article
- Figures
- Metrics
- Preview PDF
- Reference
- Related
- Cited by
- Materials
Abstract:
The weather system on 600 hPa can analyse the main characteristics of the variation of low vortex over the western Sichuan Plateau and identify the relationship between the development and movement of low vortex and the heavy precipitation area over the western Sichuan Plateau. Therefore, we are currently analyzing the spatiotemporal distribution of the vortex on 600 hPa, the relationship between low vortex and precipitation, and dynamic and thermal characteristics of vortex causing rainfall in the western Sichuan Plateau in the summer half of the year by using the 3-hour ERA5 reanalysis data (0.25°×0.25°) and the hourly precipitation data from 2011 to 2020. The results show that there are 80 low vortices per year in 42 years, and the duration of less than one day accounts for 95.7% of the total. The formation and extinction of the low vortices are affected by the topography on the east side of the plateau and the obvious diurnal variation of surface temperature. The annual average number of the low vortices generated in the western Sichuan Plateau is 61.5. The annual average number of the low vortices which move in the western Sichuan Plateau is 18. And the annual average number of the low vortices which move out of the western Sichuan Plateau is 5.3. The source area of the low vortex is located in Baiyu County in Ganzi Prefecture. And the dissipation area of the low vortex is located in Litang County in Ganzi Prefecture. The low vortices with a life history longer than 12 h account for 36.4%，which will bring precipitation. And more than 83.7% of them will cause moderate rainfall or above. The central position of the maximum daily precipitation intensity associated with the low vortex moves from the eastern and southern parts of the western Sichuan Plateau to the central part each month, and then gradually moves back to the eastern and southern parts. Correspondingly, in July and August, majority low vortices move from the north and south to the centre and wobble away. In other months, majority low vortices formed in the centre will affect the east and south areas, or generated in the south and then stagnate or wobble in situ. Strong vertical upward motion, the coupling development of positive vorticity region and the formation and maintenance of the deep unstable stratification are the dynamic characteristics and thermodynamic stratification conditions of the generation and development of vortex, causing heavy precipitation.
Keywords:
Project Supported:
Clc Number:
You are thevisitors
Supported by:Beijing E-Tiller Technology Development Co., Ltd.
Supported by:Beijing E-Tiller Technology Development Co., Ltd.