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AVISO Sea Surface Height

Program: AVISO
Spacecraft: JASON-1, TOPEX/POSEIDON, ENVISAT, GFO, ERS 1/2, GEOSAT
Sensor: Altimetry Sensors on multiple spacecraft
Primary Geophysical Parameter: Sea Surface Height
Nominal Accuracy: unknown
Spatial grid: 0.25 degrees longitude by 0.25 degrees latitude, geographic
Spatial coverage: Global
Temporal Coverage: Oct, 1992 - ongoing
FGDC Metadata
Short Description:
NOAA CoastWatch provides a measurement of sea surface height deviation (SSHD) received from the AVISO program. The AVISO (Archiving, Validation and Interpretation of Satellite Oceanographic data) program seeks to provide long-term, continuous altimetry datasets by merging past and present satellite altimetry missions. Ocean surface topography is an important measurement for understanding the fundamental processes behind ocean currents. Oceanic pressure centers can drive ocean currents much like atmospheric pressure centers drive atmospheric winds. This is a science quality dataset.
Technical Summary:
The AVISO Sea Surface Height product combines data from multiple satellites, including Jason-1, TOPEX/Poseidon, The European Remote Sensing (ERS) Satellites 1 and 2 and their sucessor, the Environmental Satellite (ENVISAT), and the Geodetic Satellite (GEOSAT) and its sucessor, the GEOSAT Follow-On (GFO). Currently, data from Jason-1, TOPEX/Poseidon, ERS 1/2, and GFO are used.

SSH is the height of the sea surface above the reference ellipsoid, a simplified approximation of the earth's surface. SSH is calculated as the difference between the satellite's altiude above the ellipsoid and the satellite's corrected range (the distance between the satellite and the ocean surface measured by the satellite's altimeter). Raw data is received and processed to altimetry data for each individual satellite, and then merged as in Ducet et al., 2000. Data are provided once every 7 days, although measurements may be taken up to 3 days before or after the single date displayed on the data. In merging data from different satellite missions, the more precise satellite missions are used as a reference for the less precise missions. Merged SSH is calculated as the weighted average of different satellite measurements. The processing is delayed to improve quality. The delay improves the data quality by allowing for a centered time window in the satellite calibrations, and by using more precise orbital positioning. For more information on the processing, see the Delayed, Merged Sea Level Anomaly Product Handbook (SALP-MU-P-EA-21065-CLS, Edition 1.5, October 2006).

Data are mapped to an equal angle grid of 0.25 degrees latitude by 0.25 degrees longitude. Further documentation, including calibration and validation statistics, is available on the AVISO website.
Disclaimer:
Despite our best efforts, incorrect data may often appear within near real time data sets. NOAA CoastWatch accepts no liability for use of these data products. It is recommended that these products NOT be used for navigation.
Acknowledgement:
If this data is used for presentation or publication, please acknowledge NOAA CoastWatch, and AVISO.
References and suggested citations:
Ducet, N., P.-Y. Le Traon, and G. Reverdin, 2000. Global high resolution mapping of ocean circulation from TOPEX/Poseidon and ERS-1 and -2. J. Geophys. Res., 105, 19477-19498.

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