Time-Integrated Radar Echo Tops as a Measure of Cloud Seeding Effects

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  • 1 Atmospheric Sciences Division, Alberta Research Council, Edmonton, Canada T6G 2C2
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Abstract

Radar echo tops of individual cells, integrated over their duration above 7.6 km, are used to define an overall storm magnitude, a growth factor after seeding, and an average seeding rate. The growth factor is then plotted as a function of the average seeding rate for 23 seeded cells and 23 randomly selected non-seeded cells. The results show an appreciable decrease not only in the range of growth factors but also in the average growth factor as the average seeding rate is increased.

Time-integrated values of other radar measures, such as reflectivity and echo coverage, that can be better related to precipitation intensity than echo tops, are suggested as more accurate and sensitive measures of the effects of cloud seeding on the radar characteristics of convective storms.

Abstract

Radar echo tops of individual cells, integrated over their duration above 7.6 km, are used to define an overall storm magnitude, a growth factor after seeding, and an average seeding rate. The growth factor is then plotted as a function of the average seeding rate for 23 seeded cells and 23 randomly selected non-seeded cells. The results show an appreciable decrease not only in the range of growth factors but also in the average growth factor as the average seeding rate is increased.

Time-integrated values of other radar measures, such as reflectivity and echo coverage, that can be better related to precipitation intensity than echo tops, are suggested as more accurate and sensitive measures of the effects of cloud seeding on the radar characteristics of convective storms.

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