OVERVIEW OF ALTIMETER DATA-PROCESSING AT THE UK EARTH OBSERVATION DATA CENTER

ERS-1 carries the fifth radar altimeter to be launched into Earth orbit. Although similar in concept and design to earlier altimeters, it is the first to include operation over non-ocean surfaces as one of its design requirements. The increased capabilities of the instrument allow for the generation of a variety of data products. The generation of these products calls for an extensive suite of software covering the processing of the raw data into basic 'waveform products', and the subsequent generation of higher level, geophysical products covering ocean, sea-ice, land-ice, land and lakes. This paper gives an overview of the ERS-1 altimeter data processing carried out at the U.K. Earth Observation Data Centre (EODC) at Farnborough. Besides processing the data from the satellite, a significant quantity of support data also have to be acquired and processed (e.g., improved orbit ephemerides, meteorological data, ionospheric data, etc.). The initial low-level processing of the raw data into the Waveform Foundation Product is common to all altimeter data products and is described in detail.