The external calibration study for EarthCARE/CPR

The Cloud Profiling Radar (CPR) is one of key sensors on EarthCARE for joint project between Europe and Japan. The CPR is developed by National Institute of Information and Communications Technology (NICT) in Japan and Japanese Aerospace Exploration Agency (JAXA). The CPR uses W-band frequency and large antenna diameter in order to obtain enough sensitivity. In other words, beam footprint becomes small but antenna scanning cannot be performed. Two external calibration methods are considered. The first method is external calibration using active radar calibrator (ARC). It is foreseen the difficulty to place exact location on sub-satellite track. The second method is external calibration using naturally distributed target, such as sea surface. We describe about test experiment for first method and statistical analysis using satellite data for second method as the feasibility study.