Abstract
ABSTRACTClimate 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.
Highlights
According to the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4), global mean surface temperature has risen by 0.74 ± 0.18°C during the last 100 years (1906–2005), and the rate of warming over the last 50 years is almost 0.13 °C/decade (IPCC, 2007)
The maximum mean wind speed occurs in the Hoh Xil area and the Qaidam Basin, with smaller values in the south and east of the TP
The minimum mean wind speed is recorded in eastern Tibet and northern Sichuan
Summary
According to the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4), global mean surface temperature has risen by 0.74 ± 0.18°C during the last 100 years (1906–2005), and the rate of warming over the last 50 years is almost 0.13 °C/decade (IPCC, 2007). Annual mean temperature has increased by 0.16 °C/decade during 1961-2002 (Liu and Chen, 2000), and precipitation has exhibited inconsistent trends (Kang et al, 2010). 1961-2005, the frequencies of cold days and nights in the TP have reduced at -0.85 and -2.38 days/decade, respectively, while warm days/nights have increased by 1.26 and 2.54 days/decade This has resulted in a negative trend of -0.20 °C/decade for diurnal temperature range (You et al., 2008a). In lowland China, mean wind speeds during the periods of 1969-2000, 1969-2005, 1969-2009, 1961-2007 and 1956-2004 have been studied and the decline in wind speeds is pronounced, regarded as a cause of decreased surface evaporation and dust storm frequency (Fu et al, 2011; Guo et al, 2011; Jiang et al, 2010; Xu et al, 2006; Yang et al, 2012). Understanding these forcing factors will enable future trends in wind speed to be predicted with greater confidence
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
