Direct Measurements of Vertical-Velocity Power Spectra with the Sousy-VHF-Radar Wind Profiler System

Abstract

We present power spectra of vertical velocities measured with the SOUSY-VHF-Radax wind profiler.over a 5-day period in October and November 1981. Most of the data consist of hourly vertical velocity profiles based on 12-rain averages, but, for somc periods, the radar was operated continuously, providing a profile once every 12 minutes. The frequency spectra of both the 12-rain and hourly data show slopes close to -1 for the log power versus log frequency curves in the lower troposphere, decreasing toward a slope near or around the tropopause and in the lower stratosphere. The frequency range covered by the spectra corresponds to the rangeof periods from 24 minutes to 1:5 days. Thus, the slope span the time scales characteristic of the mesoscale and synoptic scales. The 300-m height resolution of the data above 3-kin altitude allowed meaningful vertical wave-number spectra to be calculnted and showed a slope close to -1.5 for the height range from 3 to IS kin.