The Relationship between Cold-Frontal Radar Echoes and Selected Surface Kinematic Parameters

Richard D. Thomas Jr. Systems Development Office, National Weather Service, NOAA, Silver Spring, MD 20910

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David D. Houghton Department of Meteorology, University of Wisconsin, Madison 53706

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Abstract

This study examines the relationship between the radar echo parameters of area coverage and intensity, and the surface kinematic fields of divergence, divergence of moisture flux and relative vorticity. The study was limited to 11 cold frontal cases during the period March 1976–March 1977, and involved 99 echoes. Fine-resolution digitized radar data were used from two midwestern and one eastern United States sites. The data were analyzed on a computer-interactive video system. The area coverage did not correlate significantly with any of the surface parameters tested. However, the intensity parameters did show significant relationships with the surface parameters, the best being with relative vorticity. The correlations were higher when surface data from 1 h before the time of the echo were used, with coefficients as high as 0.5.

Abstract

This study examines the relationship between the radar echo parameters of area coverage and intensity, and the surface kinematic fields of divergence, divergence of moisture flux and relative vorticity. The study was limited to 11 cold frontal cases during the period March 1976–March 1977, and involved 99 echoes. Fine-resolution digitized radar data were used from two midwestern and one eastern United States sites. The data were analyzed on a computer-interactive video system. The area coverage did not correlate significantly with any of the surface parameters tested. However, the intensity parameters did show significant relationships with the surface parameters, the best being with relative vorticity. The correlations were higher when surface data from 1 h before the time of the echo were used, with coefficients as high as 0.5.

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