Vertical Structure of Atmosphere Boundary Layer during Wind-sandstorm Process over Sandstorm Source in Arid Area of Northwest China
Based on the daily observed sounding data at 08:00 and 20:00,precipitations,maximum temperatures and sandstorm real-time data of 1 811 typical wind-sandstorm cases during 1971-2008 in Minqin,a sandstorm source in arid area of Northwest China,vertical structure characteristics of atmosphere boundary layer in different months and seasons is discussed under dry-wet variation,sandstorm strength,sandstorm occurring time and sandstorm duration.The main conclusions are:(1) The maximum atmospheric mixed layer thickness during sandstorm process is larger with more than 2 500 m from April to May,but the maximum atmospheric mixed layer thickness during strong sandstorm process is larger from June to July with 2 530 m in July,the maximum atmospheric mixed layer thickness during sandstorm process is lower by 200-400 m than that during gale process from March to August.The maximum atmospheric mixed layer thickness during sandstorm process is deeper in afternoon with 2 700 m from April to May.The maximum maximum atmospheric mixed layer thickness varies inversely with the sandstorm duration.(2)The disturb and front inversion are more frequent and stronger during sandstorm process,disturb inversion' s strength is strongest up to 2.5 ℃/100m.The front inversion height is 700-1 000 m,disturb inversion height is 150-400 m.The radiation and radiation-front inversion are more frequent and stronger during gale process,and the front inversion is obviously stronger during strong sandstorm process.It shows that sandstorm is mainly resulted from strong wind disturbance in lower atmosphere and cold front above 500 m in upper atmosphere.(3)There is an obvious dry atmospheric layer above 800 hPa in daytime,but it is drier and warmer in nighttime,and a phenomenon of inversion wet is also obvious in nighttime.If the surface layer is drier and colder,northwest wind is stronger,the duration of strong sandstorm will be longer.
sandstorm sourcearid area of northwest Chinaatmosphere boundary layermaximum mixed layer depthinversion layervertical T-Td fieldwind field
NETL
NSTL
万方数据
维普
