摘要
The near-surface lapse rate reflects the atmospheric stability above the surface.Lapse rates calculated from land surface temperature(γTs)and near-surface air temperature( γTa )have been widely used.However,γTs and γTa have different sensitivity to local surface energy balance and large-scale energy transport and therefore they may have diverse spatial and temporal variability,which has not been clearly illustrated in existing studies.In this study,we calculated and compared γTa and γTs at^2200 stations over China from 1961 to 2014.This study finds that γTa and γTs have a similar multiyear national average(0.53°C/100 m)and seasonal cycle.Nevertheless,γTs shows steeper multiyear average than γTa at high latitudes,and γTs in summer is steeper than γTa ,especially in Northwest China.The North China shows the shallowest γTa and γTs,then inhibiting the vertical diffusion of air pollutants and further reducing the lapse rates due to accumulation of pollutants.Moreover,the long-term trend signs for γTa and γTs are opposite in northern China.However,the trends in γTa and γTs are both negative in Southwest China and positive in Southeast China.Surface incident solar radiation,surface downward longwave radiation and precipitant frequency jointly can account for 80%and 75%of the long-term trends in γTa and γTs in China,respectively,which provides an explanation of trends of γTa and γTs from perspective of surface energy balance.
近地表温度垂直递减率反映了地表大气稳定度.基于1961~2014年中国大陆地区约2200个地面观测站点数据,本研究计算并比较了地表温度和近地面气温温度垂直递减率(γTs和γTa)的时空变化.研究发现,γTs和γTa具有相似的多年区域平均和季节循环变化.但相较于γTs,γTa在高纬度地区的数值更高,并且夏季的γTs高于γTa.受大尺度平流影响,华北地区γTs和γTa较低,抑制了空气污染物的垂直扩散,而污染物积累可能会导致其进一步减少.因对地表太阳辐射、大气向下长波辐射及降水频率变化的敏感度不同,中国大陆地区γTs和γTa的长期变化趋势存在明显差异.温度垂直递减率在本研究的改进将有助于了解因全球变暖和污染事件的不断发展而引起的大气稳定性的变化,也将有利于未来有关区域气候变化的研究.
作者
Yanyi He
Kaicun Wang
贺嫣颐;王开存(State Key Laboratory of Earth Surface Processes and Resource Ecology,College of Global Change and Earth System Science,Beijing Normal University,Beijing 100875,China)
基金
This work was supported by the National Key Research&Development Program of China(2017YFA0603601)
the National Natural Science Foundation of China(41525018 and 41930970)。
