Atmospheric Physical Characteristics of Northwest Airflow Type Sandstorm in the East of Hexi Corridor
Based on the conventional high altitude,ground observation data and encrypted observation data with interval of 50 m at 08:00 and 20:00 of Minqin station in the east of Hexi Corridor from 2006 to 2022,the surface time variations of meteorological elements,characteristics of vertical structure and atmospheric stratification were analyzed.The results showed that:(1)The northwest airflow type sandstorm occurred when ground-air temperature and temperature difference were maximum,relative humidity was minimum,surface air pressure and wind speed increased sharply.Especially in spring,the sandstorm occurred with big wind,dry surface and strong thermal convection near surface layer.(2)The vertical structure was dry in the morning but wet in the evening,the wind speed increased with height,the wind direction turned clockwise and then reversed,the lower layer was warm and the upper layer was cold.The lower layer air temperature was higher,vertical gradient increased greatly,T-Td was bigger,intensity of cold-warm air was stronger and intersection height(near 1 km)in spring,the stratification was more unstable and sandstorms were prone to occur.(3)The bigger vertical gradient of potential temperature resulted more unstable atmosphere at 08:00 in spring and 20:00 in winter,so sandstorm appeared earlier in the day in spring.There were deeper and lower unstable stratification heights at 20:00 in spring and 08:00 in winter,so the strong sandstorm often concentrated from afternoon to night in spring and noon in winter.(4)When the center strength of cold advection(≥-34℃)and northwest jet stream(≥26 m/s)were stronger at 500 hPa,and the corresponding wind speed was greater than 20.0 m/s at 700 hPa over Hexi and the larger area of lower warm zone,the stronger the intensity and the longer the duration of the sandstorm.
morthwest airflow type sandstormground elementsvertical structurelatmospheric stratification
国家科技期刊平台
NSTL
万方数据
