Wintertime Surface Wind Patterns in the Colorado River Valley

Abstract

The diurnal variation of regional wind patterns in the complex terrain of the Grand Canyon area was investigated for wintertime fair weather days using a network of wind sensors on 10-m towers. Thermally driven along-slope and along-valley circulations were present at all sites within the region, but wind characteristics varied from site to site depending on nearby topography and exposure. Along the Colorado River upstream from the Grand Canyon, a series of subbasins produce a regional circulation system characterized by convergence of low-level air into the subbasins at night and divergence of air from the subbasins during the day. Contrary to valley wind theory expectations, locations down valley from the subbasin centers experience up-valley winds during nighttime and down-valley winds during daytime.