Monday, August 19, 2013

New paper finds warming decreases wind speeds & sunshine hours increase wind speeds

A new paper published in the International Journal of Climatology finds wind speeds in the Tibetan Plateau have decreased with warming since 1980 due to a decrease in the temperature gradient [difference] between adjacent latitudes. Contrary to the claims of climate alarmists, the paper corroborates many other peer-reviewed publications demonstrating that warming leads to decreased wind speeds and fewer cyclones/hurricanes. Conversely, the authors find that sunshine hours are significantly positively correlated with wind speeds, potentially yet another solar amplification mechanism via Svensmark's theory of cosmoclimatology.

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

Qinglong You et al

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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