RADS

Radar Altimeter Database System (RADS)

Algorithm Details

The Radar Altimeter Database System (RADS) is employed is employed at NESDIS/STAR as a enterprise multi-mission algorithm providing consistent sea level anomaly, waves, and ocean surface wind speed products. RADS is a joint effort of the NOAA Laboratory for Satellite Altimetry (LSA), EUMETSAT, and Department of Earth Observation and Space Systems (DEOS) at the Delft University of Technology to establish a harmonized, validated, and cross-calibrated sea level data base from satellite altimeter data. RADS was designed primarily as a database tool for expert altimetry users but through NOAA CoastWatch and LSA training materials, may have appeal at both expert and entry levels: advisory councils, water management authorities, teachers, and students.

RADS homogenizes data from multiple missions which in turn are used to generate Level-2P products for operational users, including data assimilation at NOAA and the US Navy (e.g. the Global Real-Time Ocean Forecast System (Global RTOFS) and the West Coast Operational Forecast System) and Level-2P and Level-3 products distributed through NOAA CoastWatch (Sea Level Anomaly and along-track altimetry). It is also used as calibration/validation platform.

The database is a collection of continually updated NetCDF datasets. Geophysical Data Records and associated corrections are processed and stored in homogenized NetCDF pass files. Near real-time processing is done two times per day at NOAA for the following missions: Jason-3, Sentinel-3A, Sentinel-3B, AltiKa/SARAL, and CryoSat-2. Reprocessing is done jointly with EUMETSAT. These files can then be used to generate products using the RADS data utilities.

Variables used within RADS include (not all inclusive):

  • Time, latitude, longitude
  • Sea level (anomaly with respect to a mean sea surface, or absolute dynamic topography)
  • Ocean surface windspeed
  • Wave height
  • Multiple options for geophysical corrections (tide models, path delays)
  • Multiple options for instrument corrections
  • Radiometer brightness temperatures
  • Radar range, orbital altitude and rate
  • Bathymetry, sea surface temperatures
  • Engineering and geophysical flags
Documentation

Scharroo, R., E. W. Leuliette, J. L. Lillibridge, D. Byrne, M. C. Naeije, and G. T. Mitchum, RADS: Consistent multi-mission products, in Proc. of the Symposium on 20 Years of Progress in Radar Altimetry, Venice, 20-28 September 2012, European Space Agency Special Publication, ESA SP-710, p. 4 pp., 2013.

RADS Data Manual The data manual describes the details of variables used in the RADS database.

Sea level Anomaly and Geostrophic Currents, multi-mission, global, optimal interpolation, gridded

Global Map projection displaying sea level anomalies

The NOAA Laboratory for Satellite Altimetry's (LSA) sea surface height team produces 0.25-degree longitude/latitude Level-3 sea level anomaly (SLA) daily datasets by applying optimal interpolation to along-track satellite observations over the global ocean from a constellation of radar altimeter missions. Theses grids are produced with near-real time (3-5 hour latency) data.  Geostrophic Currents are produced from the SLA and are included in the dataset.

Along-track significant wave height, wind speed and sea level anomaly from multiple altimeters

Global map projection showing granule tracts of significant wave height, wind speed, and sea level anomalies.

The NOAA Laboratory for Satellite Altimetry's (LSA) sea surface height team produces 0.25-degree longitude/latitude Level-3 significant wave height, wind speed, and sea level anomaly (SLA) daily datasets by applying optimal interpolation to along-track satellite observations over the global ocean from a constellation of radar altimeter missions. Theses grids are produced with near-real time (3-5 hour latency) data.

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