Journal of Geographical Sciences ›› 2008, Vol. 18 ›› Issue (2): 142-154.doi: 10.1007/s11442-008-0142-1

• Climate and Environmental Change • Previous Articles     Next Articles

Cloudiness variations over the Qinghai–Tibet Plateau during 1971–2004

ZHANG Xueqin1, PENG Lili1,2, ZHENG Du1, TAO Jie1,2   

  1. 1. Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing 100101, China|
    2. Graduate University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2007-10-12 Revised:2007-11-29 Online:2008-06-25 Published:2010-09-18
  • Supported by:

    National Basic Research Program of China, No.2005CB422006; National Natural Science Foundation of China, No.40331006; No.40201005; Knowledge Innovation Project of the CAS, No.KZCX2-YW-310;No.CXIOG-A04-03

Abstract:

With Empirical Orthogonal Function (EOF) and trend analysis method adopted, the spatio-temporal variation of total cloud amount is analyzed for 75 stations on the Qinghai–Tibet Plateau during the period 1971–2004. Analysis indicates that the total cloud amount decreases from the southeast to the northwest of the plateau, and that the annual and seasonal variations in total cloud amount both show an apparent declining tendency over the past decades. Correlation analysis demonstrates that the total cloud amount is negative with sunshine duration and diurnal temperature range (DTR), and is positive with precipitation and the relative humidity, respectively. The negative correlation is consistent with the radiative effect of cloud, while the positive correlation between total cloud amount and precipitation is obscured because of the influence of topographic factors. Discussion implies that the decrease of total cloud amount is possibly due to the variation of atmospheric aerosol content and ozone concentration over the plateau, although it is difficult to quantify the driving force mechanism up to now.

Key words: Qinghai–Tibet Plateau, total cloud amount, spatio-temporal variation, forcing