R. Marchand, J. Comstock, and S. McFarlane (2004). Retrieval of Cloud Ice Water Content and Effective Radius Using ARM Cloud Radar Reflectivity and Doppler Velocity. Fourteenth ARM Science Team Meeting Proceedings. Albuquerque, New Mexico, March 22-26, 2004.
Mace et al. (2002) and Matrosov et al. (2002) have published retrieval algorithms for cirrus microphysics (i.e., ice water content and particle size) based only on radar observed reflectivity (Z) and Doppler velocity (V). These ZV retrievals are attractive in that they do not require single layer or optically thin clouds and can therefore be applied during many periods when most other retrievals fail. In principle these retrievals can even be applied to the upper (ice only) portions of mixed phase clouds. The results shown here are based on a modified form of the Mace et al. (2002) algorithm. It differs from the Mace algorithm in that: • We permit the drop size distribution to be a gamma function of any chosen order rather than only an exponential function. • We adopt the particle mass and area to fall speed model of Mitchell et al. (1996), rather than use an empirical velocity to maximum particle dimension power law relationship. • We assume the radar scattering can be modeled as Rayleigh scattering and only depends on the particle mass, rather than use a radar cross section to maximum particle dimension power law approximation. • We adopt volume and area relationships for individual ice particle types (habits) as given by Yang et al. (2000). • We solve the resulting integral equations numerically using look-up tables. • We use a different approach to estimate the particle fall velocities from the measured radar Doppler velocity which does not involve fitting to a regression relationship and includes an empirical maximum and minimum Z to Ice Water Content (IWC) constraint.
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