Comparison of NCEP/NCAR and ERA-40 total cloud cover with surface observations over the Tibetan Plateau

Authors

  • Qinglong You,

    Corresponding author
    1. Key Laboratory of Meteorological Disaster, Ministry of Education, Nanjing University of Information Science and Technology, Nanjing, China
    • 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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  • Yang Jiao,

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

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

    1. Laboratory for Climate Studies, National Climate Center, China Meteorological Administration (CMA), Beijing, China
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  • Xianhong Meng

    1. Key laboratory of land surface process and climate change in cold and arid regions, CAS, Lanzhou, China
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ABSTRACT

The annual and seasonal total cloud cover (TCC) variations in the eastern and central Tibetan Plateau (TP) during 1961–2005 are analysed using 71 surface observational stations. The mean TCC decreases from the southeastern to the northwestern TP, consistent with the patterns of atmospheric moisture in the region. The annual mean TCC shows a significant decreasing trend of −0.09 percent decade−1, mainly contributed by winter. About 65% of the stations show significant downward trends on the annual basis with large trend magnitudes occurring in the central TP. The seasonal patterns confirm the annual patterns in most cases. Compared with the surface observations, both National Center for Environmental Prediction/National Center for Atmospheric Research reanalysis (NCEP/NCAR) (1961–2005) and ERA-40 (1961–2001) can reproduce the decreasing TCC trends. The shift of TCC before and after the mid-1980s is obvious in observations and both reanalyses, reflecting the changes of large-scale atmospheric circulation. However, NCEP/NCAR underestimates and ERA-40 overestimates observations on the annual and seasonal basis, presumably caused by the different cloud parameterization schemes. A Taylor diagram diagnose summarizes the discrepancies between observations and reanalyses.

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