Study on H_2O and CH_4 Distributions and Variations over Qinghai-Xizang Plateau Using HALOE Data

The H2O and CH4 data observed by HALOE in UARS satellite from 1993 to 2004 are used to analyze their distributions and variation features in stratosphere over Qinghai-Xizang Plateau,and compare with those in the same latitudes.Finally the trends of the H2O and CH4 in stratosphere over Qinghai-Xizang Plateau are also analyzed.The results show that the H2O mixing ratio decreases with height in upper troposphere quickly reaches a minimum near the tropopause and the bottom of stratosphere;and then it increases with height in stratosphere.The characteristic of vertical distribution of CH4 shows that it always decreases with height from 140 hPa to 1 hPa.The mixing ratio of H2O and CH4 in summer is higher than that in winter in upper-troposphere and lower-stratosphere.There is obvious difference between the mixing ratio of H2O and CH4 over Qinghai-Xizang Plateau and those over the same latitudes,especially in upper-troposphere and low-stratosphere.Vertical motion caused by the thermodynamics of the Qinghai-Xizang Plateau influences the distribution of H2O and CH4 significantly,and troposphere and stratosphere exchange is active over Qinghai-Xizang Plateau.Relation of H2O and CH4 is consanguineous in middle and upper stratospheres,this is because a principal source of stratosphere H2O is from the oxidation of CH4.The trend analyses show that the H2O mixing ratio decreased from 1993 to 2004 and CH4 mixing ratio decreased near tropopause before 1998 and after 2001.In middle stratosphere,the H2O mixing ratio increased before 2000 and then decreased after 2000;the CH4 mixing ratio decreased before 2000 and then increased after 2000.