A Climatology of the Surface Heat Source on the Tibetan Plateau in Summer and Its Impacts on the Formation of the Tibetan Plateau Vortex
LI Guoping;LU Huiguo;HUANG Chuhui;FAN Yuyue;ZHANG Bo;College of Atmospheric Sciences, Chengdu University of Information Technology;College of Meteorological Observation, Chengdu University of Information Technology;Sichuan Meteorological Observatory;
Based on NCEP/DOE(National Centers for Environmental Prediction/Department of Energy) reanalysis data of surface sensible heat and latent heat fluxes on the Tibetan Plateau(TP) and datasets of the Tibetan Plateau Vortex(TPV) recognized from MICAPS(Meteorological Information Comprehensive Analysis and Process System) weather maps, this paper studies the near 30-year(1981–2010) climatological characteristics of surface heating and generating frequency of TPVs over the TP in summer, and analyzes the temporal correlation between the TP surface heating and the TPV statistics and its physical cause. The following results are obtained: The climatic average of TP surface sensible heat fluxes in summer is 58 W m-2, showing an overall weak decreasing trend in the near 30-year period. An increasing trend is apparent in the early 1980 s and most of the first decade of the 21 st century, but a fluctuating decline between. Surface heating shows a quasi-three-year periodic oscillation, and an abrupt climate change starts around 1996. The climatic average of surface latent heat fluxes in summer is 62 W m-2, showing fluctuating changes accompanied by an increasing trend over the near 30-year period. The surface latent heat shows a quasi-four-year periodic oscillation, with an abrupt increase beginning around 2004. The climatic average of the surface heat source in summer is 120 W m-2; sensible heat and latent heat on the ground contributes the same to the surface heat source over the TP in summer. The surface heat source shows a modest weakening trend overall, with a strong phase between the 1990 s and 1980 s, an obvious weak phase in the first six years of the 21 st century, and then becomes strong again. The surface heat source shows a three-year periodic oscillation and an abrupt change from strong to weak around 1997. Based on identification using the MICAPS weather maps, the linear frequency of summer TPVs over the near 30-year period showed a certain degree of decline, with a higher frequency mainly concentrated in the 1980 s to 1990 s. The generating frequency of TPVs shows a 7-year periodic oscillation, and features an abrupt change around 1998. The generating frequency of TPVs over the same period is highly positively correlated to sensible heat but weakly negatively correlated to latent heat, but compared with the surface heat source over the TP, is still a significant positive correlation. On the climate scale, therefore, stronger periods of TP surface heating, especially surface sensible heating, correspond to the favorable formation of TPVs. From the perspective of the temporal correlation of climate statistics, this study reveals important impacts of the TP surface heating on promoting TPVs and convective activity.
【Fund】： 国家自然科学基金91337215、41175045;; 国家重点基础研究发展计划(973计划)项目2012CB417202;; 公益性行业(气象)科研专项GYHY201206042~~
【CateGory Index】： P461;P443
【CateGory Index】： P461;P443