Pulsating downslope windstorms

Abstract

A new high resolution simulation of the 11 January 1972 windstorm in Boulder, Colorado, constructed using a very large model domain, is shown to qualitatively reproduce the strong, quasi-periodic, 5-15 min transience in surface wind speed to the lee of the topography that was actually observed during this event. It is demonstrated that this transience is caused by the continuous generation of strong pulses of enhanced surface wind on the lee slope, which thereafter propagate downstream with individually constant speeds. This newly discovered pulsation phenomenon is therefore a generic property of flows induced by the breaking of topographically forced internal waves. -from Authors