Comparisons of Rawinsonde-deduced Kinematic and Thermodynamic Quantities with Those Deduced from VHF Profiler Observations

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  • 1 NOAA, Environmental Research Laboratories, National Severe Storms Laboratory, Norman, Oklahoma
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Abstract

The testing and evaluation of new observing systems (i.e., 50-MHz wind profilers) were listed among the goals of the 1985 Oklahoma–Kansas Preliminary Regional Experiment for STORM-Central (PRE-STORM). Using a PRE-STORM dataset from 12–13 May 1985, kinematic quantities computed from profiler winds are quantitatively compared with those computed from a dense network of rawinsonde wind observations. Both the generalized thermal wind equation and the geostrophic thermal wind equation are used to retrieve horizontal gradients of virtual temperature from the profiler wind observations. The resultant gradients are compared with those computed from rawinsonde temperature and moisture measurements.

Comparisons of the kinematic quantities computed from the two data sources show some agreement in temporal trends. Comparisons of the detailed structure reveal significant differences. The temporal trends of the vertical motion fields obtained from the profilers and rawinsondes do not correspond. The virtual temperature gradients retrieved using profiler winds and the generalized thermal wind equation do not agree with those computed from rawinsonde temperature and humidity data. Overall, the use of the thermal wind equation and profiler wind observations to estimate thermal gradients was not successful. An example of detailed thermal structure from rawinsonde temperature and humidity data that was successfully detected using profiler winds and the generalized thermal wind equation is presented. The sampling characteristics and other sources of errors that hinder comprehensive comparisons of the observations from the various PRE-STORM sensors are discussed.

Abstract

The testing and evaluation of new observing systems (i.e., 50-MHz wind profilers) were listed among the goals of the 1985 Oklahoma–Kansas Preliminary Regional Experiment for STORM-Central (PRE-STORM). Using a PRE-STORM dataset from 12–13 May 1985, kinematic quantities computed from profiler winds are quantitatively compared with those computed from a dense network of rawinsonde wind observations. Both the generalized thermal wind equation and the geostrophic thermal wind equation are used to retrieve horizontal gradients of virtual temperature from the profiler wind observations. The resultant gradients are compared with those computed from rawinsonde temperature and moisture measurements.

Comparisons of the kinematic quantities computed from the two data sources show some agreement in temporal trends. Comparisons of the detailed structure reveal significant differences. The temporal trends of the vertical motion fields obtained from the profilers and rawinsondes do not correspond. The virtual temperature gradients retrieved using profiler winds and the generalized thermal wind equation do not agree with those computed from rawinsonde temperature and humidity data. Overall, the use of the thermal wind equation and profiler wind observations to estimate thermal gradients was not successful. An example of detailed thermal structure from rawinsonde temperature and humidity data that was successfully detected using profiler winds and the generalized thermal wind equation is presented. The sampling characteristics and other sources of errors that hinder comprehensive comparisons of the observations from the various PRE-STORM sensors are discussed.

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