利用中国气象局提供的0. 5°*0. 5°降水和温度的日值资料,联合ERA-Interim、MERRA2( second Modern-Era Retrospective analysis for Research and Applications)和JRA-55( Japanese 55-year Reanalysis)再分析资料以及全球陆面数据同化系统( Global Land surface Data Asimilation System,GLDAS-2. 0)资料,研究了全球变暖背景下青藏高原夏季地表气温及降水的变化特征,以及该地区大气中水汽含量及水汽输送特征。结果表明,1979-1998年期间,高原的地表气温呈增加趋势,降水呈减少趋势;而在全球增温减缓期间( 1999-2010年) ,地表气温及降水较1979-1998年期间呈现更为显著的增加趋势。在青藏高原上空,大气中水汽含量在1979-2010年间整体呈增加趋势;然而,进一步分析表明,在此期间由外界向高原输送的水汽逐年降低,尤其在1998年后,由于西南季风强度的大幅减弱,使得外界向高原的净水汽输送量减少得更为显著;青藏高原地表蒸散量的分析表明,自1998年后,高原地表的蒸散量显著增加,成为高原地区大气中水汽增加的主要原因。
英文摘要:
The Qinghai-Tibetan Plateau ( QTP) ,which is aptly called as the " Asian water tower" ,acknowledged as the water source of the rest region in China,may profoundly have an significant impact on the regional and global atmospheric water vapor cycle ,climate change and incidents of drought,disastrous weather and climate evolution in China and of the world,as a whole. In this paper,combined with the reanalysis data of ERAInterim, MERRA2 ( second Modern-Era Retrospective analysis for Research and Applications) ,JRA-55 ( Japanese 55-year Reanalysis) ,and the GLDAS-2. 0 ( Global Land surface Data Asimilation System) ,the precipitation and temperature daily grid data from CMA ( China Meteorological Administration) were used to investigate the characteristics of spacial distribution and variation tendency of precipitation,temperature,atmospheric water vapor,and the atmospheric water vapor transport in summer over the QTP in summer during the period of 1979-2010 in this study. The results showed that the surface temperature over the QTP had increasing trend while the precipitation showed a decreasing trend during the period of 1979-1998. Otherwise,during the period of global warming deceleration ( 1999-2010) ,the surface temperature and the precipitation showed a more significant increasing trend than those during the period of 1979-1998. The atmospheric water vapor over the QTP showed an increasing trend during the period of 1979-2010. On the contrary,based on the further analysis,the inward transport of atmospheric water vapor showed a decreasing trend year by year. Especially,after the year of 1998,due to the sharp weakening of the intensity of southwest monsoon,the net inward atmospheric water vapor transport was reduced more significantly in this period. The results indicated that the surface evapotranspiration over the plateau showed an increasing trend significantly,which may be a major cause of the increased atmospheric water vapor over the QTP.