96 The long-term changes of tropospheric lapse rate over China and Its Relations to Surface Warming

Monday, 7 January 2013
Exhibit Hall 3 (Austin Convention Center)
Tianbao Zhao Sr., Chinese Academy of Sciences, Beijing, China

Handout (1.1 MB)

The lapse rate in the atmosphere (defined as the change in temperature with height, -dT/dz) is most often used to characterize temperature changes because earth's surface temperature and the greenhouse effect tend to go up and down with the amount of the tropospheric lapse rate. The mean tropospheric lapse rate is a balance between many processes of energy transfer, like radiation, convection, evaporation, cloud formation, and large scale air motions. In this study, the lapse rate derived from the homogenized radiosonde dataset suggests that the changes of tropospheric lapse rate over China currently tend to amplify local variations of surface temperature and of the greenhouse effect. The result shows that during 1970-2010 when the record is relatively complete, the tropospheric lapse rate shows significant upward changes, with the -dT/dz increasing by about 0.2-06oC/km per 50-year over the most China and by more than 06oC/km per 50-year over northern China in winter, which result mostly from a faster increases in temperature at the ground and mid-lower troposphere than at the mid-upper troposphere, with most of the increase occurring after mid-1980s. The variations and changes of -dT/dz are highly correlated with those in surface temperature (r~=0.60), which is higher than the correlation between the -dT/dz and the mean tropospheric temperature (r~=0.30). This implies that the long-term changes of the tropospheric lapse may obviously response to the surface warming over China.
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