Validation of EarthCARE Cloud Microphysics Retrieval with the airborne HALO Microwave Package

Kurzfassung

The EarthCARE satellite will carry a number of instruments suited for the retrieval of cloud properties. Besides a cloud radar and a lidar, passive microwave radiometers can be combined in a synergetic way. Advanced retrieval techniques will need a demonstration test bed during the development phase prior to the launch of the EarthCARE satellite, as well as the possibility for further validation during the EarthCARE mission. An airborne platform for advanced observation techniques will be provided by the new German research aircraft HALO (High Altitude Long Range). The aircraft, a Gulfstream G550, will fly its first missions in 2009. With a maximum payload of 3000 kg, a maximum ceiling of 15.5 km, a maximum endurance of 11 hours and a range of more than 9000 km, the aircraft will open a new dimension for climate and atmospheric research. The HALO Microwave Package (HAMP) will be a combination of passive and active microwave sensors. The instruments will be located in a protective belly pod beneath the aircraft fuselage. The belly pod will also have an additional lidar window, so that it will be possible to fly HAMP in combination with a lidar, thus providing a synergetic combination similar to the EarthCARE instruments. HAMP will consist of a highly-sensitive 36.5 GHz cloud radar with Doppler and polarimetric capabilities and a number of passive microwave radiometers. The low frequency of the radar allows for a much better penetration of the radar beam through convective systems in the tropics than higher frequencies. The polarization capability provides additional information about the cloud particle properties. Due to the Doppler signal processing the radar can estimate vertical velocities of cloud particles. It is currently investigated to supplement the radar with a beam-steering technique. This will additionally allow for the retrieval of the wind profile along the flight path. For the passive microwave radiometers a wide range of frequencies will be used. Measurements will be in the oxygen absorption bands at 60 and 118 GHz as well as in the water vapour absorption bands near 22 and 183 GHz. This combination of passive microwave sensors will allow for application of a number of precipitation and cloud microphysics retrieval algorithms with airborne measurements. The combination with the cloud radar and the lidar will allow for an independent validation.