EarthCARE mission has objectives to reveal aerosol and cloud interaction and to reveal relationships with radiation
budget. For this purpose, the EarthCARE satellite has four instruments, which are Atmospheric LIDAR (ATLID), Multi
Spectral Imager (MSI) and Broad Band Radiometer (BBR) in addition to Cloud Profiling Radar (CPR). CPR is
developed under cooperation of Japanese Aerospace Exploration Agency (JAXA) and National Institute of Information
and Communications Technology (NICT) in Japan.
The requirement of sensitivity is -35dBZ, therefore CPR uses W-band frequency and needs a large (2.5m) antenna
reflector. The large antenna has small footprint and is to give up antenna scanning. From this, some difficulty of external
calibration using active radar calibrator (ARC) is recognized.
One solution of external calibration is using scattering from natural distributed target, such as sea surface. Then the
measurement of sea surface scattering using airborne cloud radar was performed. The sea surface scattering property is
being prepared. Second solution is that ARC puts on exact location of sub-satellite track. Precise sub-satellite track
prediction is necessary. We focus second solution in this paper. The test experiment was demonstrated using CloudSat of
NASA/JPL, which is provided CPR using W-band frequency. The feasibility of this calibration method is discussed.
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