WHY MIE? Accurate Observations of Vertical Air Velocities and Raindrops Using a Cloud Radar

• Published in: Bulletin of the American Meteorological Society Vol. 83; no. 10; pp. 1471 - 1483
• Main Authors: Kollias, Pavlos, Albrecht, B. A., Marks, F.
• Format: Journal Article
• Language: English
• Published: Boston, MA American Meteorological Society 01.10.2002
• Subjects: Atmosphere; Backscattering; Clouds; Doppler radar; Earth, ocean, space; Exact sciences and technology; External geophysics; Geophysics. Techniques, methods, instrumentation and models; Kinetics; Meteorology; Precipitation; Radar; Rain; Raindrops; Terminal velocity; Turbulence; United States; North America; America; Vertical speed; Radiation scattering; Water drop; Clouds; Radar observation; Microwave; Mie scattering; Atmospheric precipitation; Doppler radar; Hydrometeor
• ISSN: 0003-0007; 1520-0477
• DOI: 10.1175/bams-83-10-1471

This article demonstrates an innovative method for the observation of vertical air motion and raindrop size distribution in precipitation using a 94-GHz Doppler radar. The method is particularly appealing since it is based on fundamental physics—the scattering of microwave radiation by large particles (Mie scattering). The technique was originally proposed in 1988 by Dr. Roger Lhermitte, who ironically pioneered the development of 94-GHz Doppler radars for the study of nonprecipitating clouds. Since then, no real effort for the evaluation and demonstration of the technique was undertaken. In this article, observations from stratiform rain are presented to illustrate the potential and accuracy of the method. The retrievals from this technique provide vertical air motion to an accuracy of 5–10 cm s−1. Despite attenuation, the Doppler velocity measurements remain unbiased and the data revealed high-resolution kinematical and microphysical structures within the stratiform precipitation for the first time. This article will hopefully expose the potential of this technique to the meteorological community and will serve as another example of the visionary contributions that Dr. Lhermitte has made to radar meteorology.