The calibration of the MetOp/Advanced Scatterometer (ASCAT)

The Advanced Scatterometer ASCAT is a spaceborne real aperture C-band radar with high radiometric resolution and stability. Its primary measurement objective is the determination of wind fields at the ocean surface. ASCAT is intended as a follow-on to the wind mode of the Active Microwave Instrument (AMI) on the ESA Earth Remote Sensing satellites ERS-1 and 2. It is part of the ESA/EUMETSAT MetOp mission, a series of satellites aimed at operational meteorology and climate monitoring. The paper describes the overall ASCAT calibration concept and discusses its specific advantages and limitations. For a better understanding of the system context first a brief introduction on the ASCAT system and measurement principle is given.