Observational evidence from two mountainous regions that nearsurface wind speeds are declining more rapidly at higher elevations than lower elevations: 1960-2006

Abstract

Coupling recent observed declines of terrestrial mid-latitude near-surface wind speed (u) with knowledge that high-elevation sites rapidly experience climate change led to an assessment of the regional near-surface elevation dependence of u (uZ) at two mountainous regions (central China and Switzerland). The monthly uZ were calculated from 1960-2006. In both regions uZ were higher in winter (∼2.25 m s-1 km -1) compared to summer (∼1.25 m s-1 km-1). For the first time uZ trends were calculated, the results were strongly seasonal, ranging from ∼-0.025 m s-1 km-1 a-1 in winter to ∼-0.005 m s-1 km-1 a -1 in summer. For both regions uZ trend results showed that u has declined more rapidly at higher than lower elevations, even though different u dynamics were observed. The uZ trends have important implications for climatic changes of coupled land-surface/boundary-layer processes (such as evapotranspiration) at high-elevation regions where much of the globe's fresh water is derived. Show more