Evaluation of radar multiple scattering effects in Cloudsat configuration

A. Battaglia (1) , M. O. Ajewole (2) , C. Simmer (1)

1 Meteorological Institute [Hamburg]
2 Department of Physics

MonteCarlo simulations have been performed to evaluate the importance of multiple scattering effects in co- and cross-polar radar returns for 94GHz radars in Cloudsat and airborne configurations. Thousands of vertically structured profiles derived from some different cloud resolving models are used as a test-bed. Mie theory is used to derive the single scattering properties of the atmospheric hydrometeors. Multiple scattering effects in the cross polar channel (reflectivity enhancement) are particularly elusive, especially in airborne configuration. They can be quite consistent in satellite configurations, like Cloudsat, especially in regions of high attenuation and in the presence of highly forward scattering layers associated with snow and graupel particles. When the cross polar returns are analysed, high LDR values appear both in space and in airborne configurations. The LDR signatures are footprints of multiple scattering effects since they cannot be explained by single scattering computations, even including non-spherical particles. We see these signatures confirmed by some experimental data collected during the Wakasa Bay experiment. Multiple scattering effects can be important for Clousat applications like rainfall and snowfall retrievals since single scattering based algorithms will be otherwise burdened by positive biases.

Domaines: Océan, Atmosphère

A. Battaglia, M. O. Ajewole, C. Simmer. Evaluation of radar multiple scattering effects in Cloudsat configuration. Atmospheric Chemistry and Physics Discussions, 2006, 6 (4), pp.8125-8154. ⟨hal-00302080⟩