南亚夏季风爆发前后青藏高原地表热通量的长期变化特征分析

Long-term variation characteristics of surface heat flux over the Tibetan Plateau before and after the onset of the South Asian summer monsoon

  • 摘要: 青藏高原作为世界第三极,其热力强迫作用不仅对亚洲季风系统的发展和维持十分重要,也会对大气环流场产生深远影响。利用欧洲中期天气预报中心(ECMWF)的ERA-Interim中1979-2016年3-10月青藏高原及其周边地区的地表热通量月平均再分析资料,通过分析得出以下结论:3-5月青藏高原主体由感热占据,感热强度快速上升且呈西高东低的分布态势,潜热强度较小但随时间而增强。季风爆发后的6-8月,青藏高原感热强度减弱,潜热强度迅速增强且呈东高西低的分布特征。季风消退后的9-10月,感热与潜热强度相当,但感热呈现出西高东低的分布特征。过去38年,青藏高原地表感热总体呈现微弱下降趋势,潜热呈较弱上升趋势。青藏高原西部地区感热呈微弱下降趋势,潜热呈上升趋势。东部感热呈较为明显的下降趋势且近年来变化趋势增强,东部潜热通量则呈现较为明显的上升趋势,分析结论与近期全球变暖条件下青藏高原气候变暖变湿这一变化状况一致,通过对青藏高原地表热通量的变化分析为下一步运用第三次青藏高原大气科学试验所获资料分析青藏高原上空大气热源的变化以及地表加热场如何影响大气环流奠定基础。

     

    Abstract: As the "Third Pole of the world", the thermal forcing of the Tibetan Plateau is very important for the Asian summer monsoon system; it also has great influences on the atmospheric circulation. In this paper, the European Medium Weather Forecasting Center (ECMWF) ERA Interim monthly mean reanalysis data of surface heat fluxes in the Tibetan Plateau and its surrounding areas is used. The time series of data are for March-October from 1979 to 2016 (data and method). Through the analysis of the above information, the following conclusions are reached. From March to May, the main body of the Tibetan Plateau is occupied by sensible heat flux, which increases rapidly with higher values in the west. The change of latent heat flux is smaller but increases with time. After the onset of the Asian summer monsoon, the sensible heat flux over the Tibetan Plateau decreases and latent heat flux increases rapidly. The distribution of latent heat flux shows higher values in the east and lower values in the west of the Tibetan Plateau. After the Asian summer monsoon is over, the intensities of sensible and latent heat fluxes are close to each other with higher sensible heat flux in the west and lower flux in the east. The surface sensible heat flux of the Tibetan Plateau shows a slightly downward trend, while latent heat shows an increasing trend over the past 38 years. The sensible heat flux in the western part of the Tibetan Plateau shows a weak decreasing trend, whereas the latent heat flux is increasing. In the eastern part of Tibetan Plateau, the sensible heat decreases and the latent heat shows a more obvious upward trend, which is also consistent with the climate change in the Tibetan Plateau. This is the basis for further studies that will use the data from The Third Qinghai-Xizang Plateau Atmospheric Science Experiment to analyze the change of atmospheric heat flux over the Tibetan Plateau and how the surface heating field affects the atmospheric circulation.

     

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