Observed surface wind speed in the Tibetan Plateau since 1980 and its physical causes

Authors

  • Qinglong You,

    Corresponding author
    1. Key Laboratory of Meteorological Disaster, Ministry of Education, Nanjing University of Information Science and Technology, Nanjing, China
    2. Max Plank Institute for Meteorology, KlimaCampus, Hamburg, Germany
    • Correspondence to: Q. You, Key Laboratory of Meteorological Disaster, Ministry of Education, Nanjing University of Information Science and Technology, Nanjing 210044, China. E-mail: yqingl@126.com

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  • Klaus Fraedrich,

    1. Max Plank Institute for Meteorology, KlimaCampus, Hamburg, Germany
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  • Jinzhong Min,

    1. Key Laboratory of Meteorological Disaster, Ministry of Education, Nanjing University of Information Science and Technology, Nanjing, China
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  • Shichang Kang,

    1. State Key Laboratory of Cryospheric Science, Chinese Academy of Sciences (CAS), Lanzhou, China
    2. Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, CAS, Beijing, China
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  • Xiuhua Zhu,

    1. Max Plank Institute for Meteorology, KlimaCampus, Hamburg, Germany
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  • Nick Pepin,

    1. Department of Geography, University of Portsmouth, Portsmouth, UK
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  • Ling Zhang

    1. Key Laboratory of Meteorological Disaster, Ministry of Education, Nanjing University of Information Science and Technology, Nanjing, China
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ABSTRACT

Climate warming on the Tibetan Plateau (TP) potentially influences many climate parameters other than temperature including wind speed, cloudiness and precipitation. Temporal trends of surface wind speed at 71 stations above 2000 m above sea level in the TP are examined during 1980–2005. To uncover causes of observed trends in wind speed, relationships with surface temperature, a TP index and sunshine duration are also analysed. The TP index is calculated as the accumulated 500 hPa geopotential height above 5000 m over the region of 30°N–40°N, 75°E–105°E from NCEP/NCAR reanalysis. The annual mean wind speed patterns during 1980–2005 are similar to those in different seasons, with higher wind speeds in the northern and western parts of the TP. Highest mean wind speeds occur in spring and lowest in autumn. During 1980–2005, annual and seasonal mean wind speeds show statistically decreasing trends at most stations. The mean trend magnitude for annual mean wind speed is −0.24 m s−1 decade−1, with the maximum decline in spring (−0.29 m s−1 decade−1) and minimum in autumn (−0.19 m s−1 decade−1). Both annually and in different seasons, wind speed is significantly negatively correlated with mean temperature, minimum temperature, maximum temperature, and the TP index, but significantly positively correlated with sunshine duration. Wind speed trends fail to show a simple elevation dependency but speeds are positively correlated with meridional surface temperature/pressure gradients. Warming in the TP may weaken the latitudinal gradients of both regional temperature and surface pressure, thus altering the regional atmospheric circulation and accounting in part for the observed decline of wind speed.

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