32nd Conference on Broadcast Meteorology/31st Conference on Radar Meteorology/Fifth Conference on Coastal Atmospheric and Oceanic Prediction and Processes

Wednesday, 6 August 2003: 5:30 PM
Investigating the density of ice particles using dual-wavelength Doppler radar
Nicolas Gaussiat, University of Reading, Reading, Berks, United Kingdom; and A. J. Illingworth
Poster PDF (359.7 kB)
Observations of ice water content are needed to evaluate the performance of models used for forecasting weather and climate change. Recent papers have demonstrated that dual-wavelength radar technique can reliably determine ice particle concentration, mean volume diameter, and ice water content in ice clouds. But the results still depend widely on the choice of the ice density function. As well as reflectivity ratio the Doppler velocity difference depends on particle size - Mie scattering reduces Z at the higher frequency; it also reduces the observed Doppler velocity, which is weighted by Z. Since, both reflectivity ratio and Doppler velocity difference depend differently on the density function, the relationship between the Doppler velocity difference and reflectivity ratio is dependent on the choice of the density function only. By comparing model output and measurements, we show that a best density function can be inferred.

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