Gustiness of downslope winds

A particular characteristic of downslope windstorms is a large difference between the mean wind speed and maximum gusts. In order to investigate the structure of the downslope winds in time, wind speed in downslope flow has been observed at high temporal resolution as a part of the SNEX campaign. During periods of extreme gustiness, a relatively large part of the energy spectrum of the wind speed oscillations is concentrated at perods of a few minutes, while during periods of weaker gusts there is more energy at periods less than one minute. A high-resolution numerical simulation does not reproduce the oscillations in the wind speed, neither on the short time-scales of less than one minute nor on the time scales of up to 10-20 minutes.