Mid-Pliocene Westerlies from Plio MIP Simulations  

作　　者：LI Xiangyu JIANG Dabang ZHANG Zhongshi ZHANG Ran TIAN Zhiping YAN Qing 

机构地区：[1]Nansen–Zhu International Research Centre,Institute of Atmospheric Physics,Chinese Academy of Sciences [2]University of Chinese Academy of Sciences [3]CAS Center for Excellence in Tibetan Plateau Earth Sciences [4]Climate Change Research Center,Chinese Academy of Sciences [5]Uni Research,Bjerknes Centre for Climate Research

出　　处：《Advances in Atmospheric Sciences》2015年第7期909-923,共15页大气科学进展（英文版）

基　　金：the Pliocene Model Intercomparison Project (Plio MIP) modeling groups (listed in Table 1 of this paper) for producing and making available their model output;supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDB03020602);the National Natural Science Foundation of China (Grant Nos. 41430962 and 41421004)

摘　　要：The midlatitude westerlies are one of the major components of the global atmospheric circulation. They play an important role in midlatitude weather and climate, and are particularly significant in interpreting aeolian sediments. In this study, we analyzed the behavior and the possible mechanism involved in the change of the westerlies, mainly in terms of the jet stream position, in the mid-Pliocene warm period （3.3 to 3.0 million years ago） using simulations of 15 climate models from the Pliocene Model Intercomparison Project （PlioMIP）. Compared to the reference period, the mid-Pliocene midlatitude westerlies generally shifted poleward （approximately 3.6° of latitude in the Northern Hemisphere and 1.9~ of latitude in the Southern Hemisphere at 850 hPa level） with a dipole pattern. The dipole pattern of the tropospheric zonal wind anomalies was closely related to the change of the tropospheric meridional temperature gradient as a result of thermal structure adjustment. The poleward shift of the midlatitude westerly jet corresponded to the poleward shift of the mean meridional circulation. The sea surface temperatures and sea ice may have affected the simulated temperature structure and zonal winds, causing the spread of the westerly anomalies in the mid-Pliocene between the atmosphere-only and coupled atmosphere-ocean general circulation model simulations.The midlatitude westerlies are one of the major components of the global atmospheric circulation. They play an important role in midlatitude weather and climate, and are particularly significant in interpreting aeolian sediments. In this study, we analyzed the behavior and the possible mechanism involved in the change of the westerlies, mainly in terms of the jet stream position, in the mid-Pliocene warm period （3.3 to 3.0 million years ago） using simulations of 15 climate models from the Pliocene Model Intercomparison Project （PlioMIP）. Compared to the reference period, the mid-Pliocene midlatitude westerlies generally shifted poleward （approximately 3.6° of latitude in the Northern Hemisphere and 1.9~ of latitude in the Southern Hemisphere at 850 hPa level） with a dipole pattern. The dipole pattern of the tropospheric zonal wind anomalies was closely related to the change of the tropospheric meridional temperature gradient as a result of thermal structure adjustment. The poleward shift of the midlatitude westerly jet corresponded to the poleward shift of the mean meridional circulation. The sea surface temperatures and sea ice may have affected the simulated temperature structure and zonal winds, causing the spread of the westerly anomalies in the mid-Pliocene between the atmosphere-only and coupled atmosphere-ocean general circulation model simulations.

关 键 词：mid-Pliocene WESTERLY climate model PlioMIP 

分 类 号：P434[天文地球—大气科学及气象学]