Satellite observations of the microstructure of natural and seeded severe hailstorms in Argentina and Alberta

Microphysical retrievals of cloud microstructure and precipitation processes has been made possible recently by the first author (Rosenfeld and Lensky, 1998), and was used to observe the impact of smoke (Rosenfeld, 1999) and industrial air pollution (Rosenfeld, 2000) on cloud microstructure and precipitation forming processes.

These methods were applied for study of the microstructure of the severe hail storms in Argentina. The retrievals revealed that the hailstorms occurred from clouds with little coalescence and an extremely deep supercooled water zone, glaciating at the homogeneous freezing level, or about -39^oC isotherm. These retrievals were validated by aircraft. The aircraft measurements are presented in a companion paper.

The satellite measurements of seeded towers in the hailstorms showed that some of them glaciated at temperatures as warm as -15^oC, in agreement with the aircraft observations. The space borne measurements provide a valuable tool for assessing the effectiveness of the seeding, including the targeting and its efficacy in freezing the supercooled cloud, which in turn suppresses the hail according to the conceptual model guiding the cloud seeding operations.

References:

Rosenfeld D. and I. M. Lensky, 1998: Spaceborne sensed insights into precipitation formation processes in continental and maritime clouds. The Bulletin of American Meteorological Society, 79, 2457-2476.

Rosenfeld D., 1999: TRMM Observed First Direct Evidence of Smoke from Forest Fires Inhibiting Rainfall. Geophysical Research Letters. 26, (20), 3105-3108.

Rosenfeld D., 2000: Suppression of Rain and Snow by Urban and Industrial Air Pollution. Science, 287 (5459), 1793-1796.