Cooperative Institute for Research in Environmental Sciences

Science Rendezvous > 2009 Posters
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Simultaneous estimation of cloud and rainfall parameters using radars operating at different frequencies

Sergey Matrosov and M. Shupe

A remote sensing approach is suggested to simultaneously retrieve cloud and rainfall parameters in precipitating cloud systems from collocated measurements taken by the vertically pointing 3-mm and 8-mm cloud radars. Additional constraining information is provided by the KVNX NEXRAD radar located at a distance of 60 km from the site of mm-wavelength radars. This approach is applicable to stratiform precipitation events with “bright-band” features, which correspond to the melting layer and are readily identifiable in radar measurements. The differential dual-wavelength attenuation scheme is used in the rain layer to simultaneously retrieve cloud liquid water path (LWP) and the rain rate. The measurements of the ground-based impact disdrometer and the rain gauge are used for constraining the retrieval information. The 8-mm radar measurements are then used to retrieve the ice water path (IWP) of the cloud parts observed above the freezing level. The IWP estimates are based on the absolute radar reflectivities. To account for the attenuation in absolute mm-wavelength radar measurements caused by the rain and melting layers and also by the wet radome, reflectivities from the KVNX radar are used for correcting measured reflectivities from vertically pointing cloud radars. The KVNX reflectivities observed over the SGP site in the ice part of the precipitating cloud system are used for this correcting procedure. Non-Rayleigh scattering effects are accounted for when comparing mm-wavelength and KVNX measurements. The suggested approach is applied to a case study. The qualitative comparisons with the lidar data indicate that the radar determined cloud liquid areas correspond well with the cloud boundaries as indicated by lidar measurements.