Effects of Small-Scale Vertical Motion on Radar Measurements of Wind and Temperature Profiles

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  • 1 Wave Propagation Laboratory, Forecast Systems Laboratory, National Oceanic and Atmospheric Administration, U.S. Department of Commerce. Boulder, Colorado
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Abstract

Vertical velocities were observed during the month of June 1990 with two side-by-side wind profilers at Platteville, Colorado. Many of the observations reveal strong wave motion, probably mountain lee waves, that sometimes caused vertical velocity changes of several meters per second in less than an hour. It is demonstrated that, under these conditions, hourly averages cannot always be used to accurately account for the effects of vertical motion on the profiler measurements. It is also shown that it is impossible to accurately remove the effects of vertical motion from the horizontal wind component estimates when the horizontal scale of vertical-motion variability is comparable to the horizontal separation distance between antenna beams. The Radio Acoustic Sounding System (RASS) temperature measurements, however, are not affected by the small spatial scales because those measurements are made on the same vertical antenna beam as the vertical velocity measurements. Nevertheless, it is important that these temperature measurements be made simultaneously with vertical velocity measurements so that valid vertical velocity corrections can be made.

Abstract

Vertical velocities were observed during the month of June 1990 with two side-by-side wind profilers at Platteville, Colorado. Many of the observations reveal strong wave motion, probably mountain lee waves, that sometimes caused vertical velocity changes of several meters per second in less than an hour. It is demonstrated that, under these conditions, hourly averages cannot always be used to accurately account for the effects of vertical motion on the profiler measurements. It is also shown that it is impossible to accurately remove the effects of vertical motion from the horizontal wind component estimates when the horizontal scale of vertical-motion variability is comparable to the horizontal separation distance between antenna beams. The Radio Acoustic Sounding System (RASS) temperature measurements, however, are not affected by the small spatial scales because those measurements are made on the same vertical antenna beam as the vertical velocity measurements. Nevertheless, it is important that these temperature measurements be made simultaneously with vertical velocity measurements so that valid vertical velocity corrections can be made.

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