Retrieval of atmospheric attenuation using combined ground-based and airborne 95-GHz cloud radar measurements

Cloud measurements at millimeter-wave frequencies are affected by attenuati on due to atmospheric gases, clouds, and precipitation. Estimation of the t rue equivalent radar reflectivity, Z(e), is complicated because extinction mechanisms are not well characterized at these short wavelengths. This pape r discusses cloud radar calibration and intercomparison of airborne and gro und-based radar measurements and presents a unique algorithm for attenuatio n retrieval. This algorithm is based on dual 95-GHz radar measurements of t he same cloud and precipitation volumes collected from opposing viewing ang les. True radar reflectivity is retrieved by combining upward-looking and d ownward-looking radar profiles. This method reduces the uncertainty in rada r reflectivity and attenuation estimates, since it does not require a prior i knowledge of hydrometeors' microphysical properties. Results from this te chnique are compared with results retrieved from the Hitschfeld and Bordan algorithm, which uses single-radar measurements with path-integrated attenu ation as a constraint. Further analysis is planned to employ this dual-rada r algorithm in order to refine single-radar attenuation retrieval technique s, which will be used by operational sensors such as the CloudSat radar.