Towards A Global Operational Altimeter Service: Rads

DEOS' anticipation of the need for global altimeter services started the Radar Altime- ter Database System (RADS) project. Embedded in the Netherlands Earth Observa- tion NETwork (NEONET), this project is supported by the Dutch government. After defining the database content, collecting altimeter and ancillary data from all available altimeter missions and combining them with the latest (correction) models, we have arrived at an (inter)nationally appreciated validated, calibrated and consistent altime- ter data set, comprising over 15 years of valuable sea level, wave height and wind data. Major assets of RADS are the upgraded ERS orbits and the flexible data organization. Our aim has been the improvement of the algorithms for converting satellite data to the final geophysical products. Global altimeter data from various satellites have been inter-compared or compared to external data, like tide gauges and wind speed read- ings. Also: ironing out inconsistencies in significant wave height, sea state, inverse barometer, wet troposphere corrections, orbits, biases, drifts, and time tagging.

This paper presents RADS. Access to the database runs through a web portal: http://www.deos.tudelft.nl/altim/rads. At this address also status, higher level prod- ucts, software, and literature can be obtained. Finally, examples are given of putting in RADS in research and education. RADS has been successfully used at Delft Hy- draulics in a data assimilation scheme for improving tides and storm surge predictions, showing the importance of near real-time observations, at the KNMI for ENSO stud- ies, and at NIOZ for seasonal variability studies in the Northern Atlantic.