Hydrometer Classification with Elliptical Polarization Radar: Applications for Glaciogenic Cloud Seeding

Authors

  • Roger F Reinking Environmental Technology Laboratory NOAA/ERL Boulder, CO
  • Sergey Y Matrosov CIRES University of Colorado/NOAA Boulder, CO
  • Roelof T Bruintjes Research Applications Program NCAR Boulder, CO

Abstract

Polarization capabilities of 8.66-mm-wavelength radar and corresponding hydrometeor depolarization calculations now provide the basis for identifying individual types of ice and liquid hydrometeors within clouds and precipitation. Model results and radar measurements with correlated snow crystal samples from winter stratiform and convective orographic clouds are examined. The results are interpreted to illustrate how this method for estimating hydrometeor types can be applied to monitor cloud evolution and evaluate the potentials and effects of glaciogenic cloud seeding. This information is derived from hydrometeor depolarizations (and related cloud reflectivities) associated with cloud phase transition, snow crystal growth habit, graupel development, snow crystal aggregation, the presence and nature of the melting level, and the distinction of rain from drizzle below the melting level. The radar’s polarization capability offers the opportunity to monitor the development of hydrometeors in the volume of cloud affected by seeding or by natural processes. Spatial gradients in hydrometeor types, rates at which a volume is transformed, and the form of precipitation can also be estimated. These features are all important for verifying the changes in hydrometeors introduced by seeding and interpreting the rates and mechanisms by which the changes occur.

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Scientific Papers