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Lanzhou University (2019)

Numerical Simulation of Boundary Layer Height and Its Effect on Dust Weather in Arid and Semi-Arid Regions of Northwest China

谭子渊;

Titre : Numerical Simulation of Boundary Layer Height and Its Effect on Dust Weather in Arid and Semi-Arid Regions of Northwest China

Auteur : 谭子渊;

Grade : Master’s Theses 2019

Université : Lanzhou University

Résumé
The atmospheric boundary layer is an important medium for the exchange of material and energy between the surface and the atmosphere.The formation of some catastrophic weather phenomena is mostly closely related to the boundary layer process.As a kind of catastrophic weather closely related to the boundary layer,dust weather has a great influence on human life and production and ecological environment.The arid and semi-arid regions of northwest China have become one of the most frequent dust weather areas in China due to its special geographical location and climatic conditions,and have unique atmospheric boundary layer characteristics.It is of great significance to study the characteristics of boundary layer height and its influence on dust weather in order to explore the formation mechanism of dust weather,early warning,disaster prevention and mitigation.Firstly,this paper studies the spatial and temporal distribution characteristics of the boundary layer and the optimal combination of the parametric scheme for the deep boundary layer simulation in the arid and semi-arid region of northwest China by using ERA-Interim reanalysis data and WRF model.Secondly,the spatial and temporal distribution of dust weather in 5 representative areas and the characteristics of boundary layer height change under dust weather conditions are analyzed.Then the causes and effects of a typical dust weather in northwest China are analyzed by using a variety of meteorological data.Finally,use WRF-Chem model to simulate the dust transmission process,boundary layer height characteristics of the typical dust weather,as well as the influence of surface heat flux on the boundary layer height and the accompanying change of the vertical distribution of dust,the main conclusions are as follows :(1)the boundary layer height in 5 representative areas is higher in late spring and summer(the highest is 2,485 3,502m in June)and lower in autumn,winter and early spring(the lowest is758 907m in December).The seasonal variations of the boundary layer height are smaller at 02:00BJT and 08:00 BJT,while the variations are relatively larger at 14:00BJT and 20:00 BJT.The atmospheric boundary layer with heights more than 4,000m generally exists in late spring and summer.The boundary layer heights is higher in the arid region than in the semi-arid region as well as the deep-developed boundary layer lasts longer in the arid area.However,at 08:00 BJT and 20:00 BJT the boundary layer heights in Minqin and Yuzhong are relatively higher in summer,and there is little difference between areas in winter.Deep atmospheric boundary layer height persists for a long time during daytime in arid areas in summer,the average duration of atmospheric boundary layer over 2000 m in Dunhuang from May to August in extreme arid area is more than 6 hours,the higher atmospheric boundary layer lasted for more than 6 hours only in June to July in Jiuquan and Minqin.(2)The numerical simulation results show that there is a significant difference between different combinations of parameterization schemes to simulate the deep-developed boundary layer in these areas.Among the three types of parameterization schemes that are relatively closely related to the development of the boundary layer,the selection of short-wave radiation scheme,land surface process scheme and boundary layer scheme has different influence on the numerical simulation results of boundary layer height.The influence of the simulation results on the deep boundary layer in Dunhuang,Minqin,Yuzhong and Lanzhou from large to small,which is the boundary layer scheme,the land surface process scheme and the short-wave radiation scheme,while Jiuquan is the boundary layer scheme,the short-wave radiation scheme and the land surface process scheme.The combination Goddard+SLAB+ACM2 performs better in the extreme arid area Dunhuang,and the arid area Jiuquan and Minqin,while the simulation effect of combination Dudhia+Noah+ACM2 is better in the semi-arid areas,Yuzhong and Lanzhou

Mots clés : Dust weather; Boundry layer height; Spatial and temporal distribution; Numerical simulation; Parameterization scheme; Northwest China;

Présentation (CNKI)

Page publiée le 4 décembre 2019