Jun 2, 2012

Causes for decadal variations of wind speed over land: Sensitivity studies with a global climate model

Bichet, A., Wild, M., Folini, D., Schär, C.
Geophysical Research Letters
  • States that over the past 30 years, observations indicate a decline of about −0.3 m/s in the northern mid-latitudes land surface wind speed
  • States the picture is less conclusive for the Southern Hemisphere and over the oceans
  • States such a stilling can affect surface evaporation and climate feedback processes, and may impact technical applications such as wind power
  • Uses an atmospheric global climate model to perform sensitivity experiments for the period 1870–2005 to assess the role of changing roughness length, aerosol emissions, sea surface temperature, and greenhouse gas concentrations in surface wind speed changes
  • Finds the wind speed trends simulated by the model generally underestimate the observed trends (land and ocean)
  • Finds that over land, the model can reproduce the observed stilling by increasing the roughness length by a factor of 1.2 to 4.9, depending on region
  • Finds that the other forcings examined can also decrease the 10 m wind speeds (up to 15% of observed values in Europe), particularly those related to increasing aerosol emissions (up to −0.2 m/s in India)
  • Results show that compared to observations, the simulated impact of climate forcings on global wind speeds over land and ocean is however small and not always significant