Temperature inversion characteristics of low-air atmosphere of Urumqi City

In order to analyze the change characteristics of low-air temperature inversion,the original daily sounding records in Urumqi Meteorological Station were used to get the ground temperature inversion,heights of bottom and peak of untouched temperature inversion,temperature and analyze their temperature changes from 2000 to 2004.The results show that there is an infirmly-steady low-air temperature inversion over Urumqi City all the year round.In winter,the temperature inversion characteristic is the most remarkable with the strongest intensity,the highest occurring frequency,and the thickest ground inversion.Their average intensity,occurring frequency and ground inversion thickness are 1.06 ℃/100 m,89 percent and 860 m,respectively.The average temperature inversion intensity is stronger than that of Lanzhou,Guiyang,Changchun and Beijing city zone and the average ground temperature inversion is thicker than that of Lanzhou,Guiyang,Changchun and Jinan in winter.The heights of untouched inversion bottom and inversion peak are 534 m and 1 187 m respectively.Because of the cold air from Mongolian anticyclone accumulating in the Junggar Basin and 5 months steady snow accumulation,the ground layer atmosphere in Urumqi City is relatively steady in winter.