83 Impact of Choices made when Creating Composite Soundings: Feature versus Height Averaging and Moisture Variable Considerations

Monday, 5 November 2012
Symphony III and Foyer (Loews Vanderbilt Hotel)
Alexander R. Zarnowski, University of North Dakota, Grand Forks, ND; and M. S. Gilmore

Handout (2.6 MB)

The main purpose of this study is to compare the following two techniques for creating sounding composites: feature-averaging from Brown (1993) and traditional height averaging. Examined are the impacts of the compositing choice on the resulting wind and thermodynamic features and derived variables (such as CAPE, CIN, LCL, LFC, and precipitable water) for three groups of soundings found in proximity to the following supercell classes: Classic (CL), Low-precipitation (LP), and High Precipitation (HP supercells). The Brown (1993) method prevents smoothing of the magnitudes of characteristic sounding features that would otherwise occur with height averaging such as the maximum height and temperature within the capping inversion, maximum jet stream wind, and maximum boundary-layer moisture. A secondary purpose is to extend the results of Brown (1993) and compare the impact of averaging different moisture variables (dewpoint, relative humidity, water vapor mixing ratio, or wet-bulb potential temperature) for each averaging framework. The resulting sounding-derived variables from the various sounding composites are then compared to those from the original soundings and to each other. We also comment on the appropriate way to merge the averaged thermodynamic and wind profiles from the same class.

These results are important for future researchers who are developing composite soundings representative of the near-storm environment for various storm classes and for those who wish to study those storm classes using idealized numerical experiments.

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