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Lanzhou University (2022)

The Formation Mechanism and Sensitivity Test of A Rainstorm Process in the Extreme Arid Area of South Xinjiang Basin

莫绍青

Titre : The Formation Mechanism and Sensitivity Test of A Rainstorm Process in the Extreme Arid Area of South Xinjiang Basin

Auteur : 莫绍青

Grade : Master 2022

Université : Lanzhou University

Résumé partiel
Rainstorm is one of the most frequent disastrous weathers in China,but in the extremely arid area of southern Xinjiang,the occurrence of heavy rain needs not only enough water vapor,but also cooperates with local terrain features and underlying surface features,meanwhile,land-atmosphere interaction also plays an important role in the occurrence and development of heavy rainfall.In this paper,the synoptic situation,water vapor source budget and trigger mechanism of a rainstorm in southern Xinjiang basin are preliminarily discussed by using FNL,ERA5 reanalysis data,automatic meteorological station observation data and FY-2G radiation brightness temperature data.Afterwards,parameterization scheme is applied to the WRF model in order to carry out sensitivity analysis of the land surface process during the rainstorm process,then the influence that the land-atmosphere interaction imposed on the rainstorm is discussed.Based on the optimal parameterization scheme of land surface process,the terrain sensitivity experiment is carried out to study the effect of topographic height on rainstorm.The main conclusions are as follows:The persistent heavy precipitation in southern Xinjiang which occurred under the background of the large-scale circulation with two-body distribution of South Asia high,was caused by the joint action of 200 h Pa upper southwest jet,the vortex of Balkhash Lake on 500 h Pa,Iran high pressure ridge,700 h Pa shear line and surface convergence line.The water vapor of the rainstorm mainly comes from the Atlantic Ocean,the Black Sea,the Li / Aral Sea,the Arabian Sea and the Bay of Bengal,and reaches the southern Xinjiang basin along the northwest,west and southwest paths.Water vapor is mainly delivered from the upper troposphere of the southern boundary and the lower and upper troposphere of the northern boundary to the southern Xinjiang basin,and is discharged in the lower and upper troposphere of the eastern boundary.The mesoscale convergence line caused by the high topography in the south of southern Xinjiang is an important trigger system for this heavy precipitation.The water vapor brought by the northwest air flow to the north of the convergence line accumulates in front of the mountain,and under the action of topographic uplift and the promotion of the convergence line,unstable energy is released,resulting in the generation and development of the convective system,causing heavy precipitation in the southern Xinjiang basin.

Mots clés : South Xinjiang basin rainstorm ;Water vapor source and budget ;Numerical simulation ;Land surface parameterization scheme ;Terrain;

Présentation (CNKI)

Page publiée le 24 octobre 2022