Study on Meteorological Elements Structure of Atmospheric Surface Layer over Desert Area in Spring

The characteristics of meteorological elements of atmospheric surface layer in spring were studied based on the observational data of wind speed,wind direction,temperature and relative humidity obtained from 20m meteorological tower in Zhurihe of Inner Mongolia from January,2005 to April,2006.The results show that the temperature rises rapidly,the wind speed is maximal and the relative humidity is minimal in spring,which is beneficial to drive sand,so the sand dust weather is frequent.The wind speed profile accords with exponential function and the exponential coefficient m could reflect well the change of wind speed at different altitudes.In sand storm,blowing sand,clean air and floating dust weather conditions,the wind speed in atmospheric surface layer raises gradually in spring.Meanwhile,the turbulent exchange coefficient diminishes gradually in spring.The main wind direction is southwest.Compared with clean air,the average rate of temperature increase is larger in floating dust,less in blowing sand.And the change of temperature reduces in dust storm,which is 061℃·h-1.There is a positive correlation between the average rates of relative humidity decrease and temperature increase,and also between those of relative humidity increase and temperature decrease in all layers.Compared with clean air,the average rate of decrease is larger in floating dust,less in blowing sand.And the change of relative humidity enhances in dust storm,which is 280%·h-1.