Optical Remote Sensing of Ice in Clouds

Authors

  • P Pilewskie NASA Ames Research Center Atmospheric Physics Research Branch Moffett Field, CA
  • S Twomey NASA Ames Research Center Atmospheric Physics Research Branch Moffett Field, CA

Abstract

A practical method of inferring cloud phase with potential applications in weather modification is presented. The instrument used is a ground-based passive spectroradiometer which measures cloud spectral reflectance or transmittance; differences between ice and liquid water near-infrared absorption spectra are the basis for phase discrimination, the results show that reflectance spectra from cumulus towers abruptly change on the order of minutes due to the conversion of liquid water to ice. Transmission measurements from overlying stratiform clouds are presented and shown to aIso be useful in predicting cloud phase.

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Scientific Papers