The sea surface is a dynamic mixture of bumps and dips resulting from a variety of factors including gravity, ocean currents and the rotation of the Earth. Scientists study variations in sea surface height using radar altimeters on satellites. These altimeters emit radar pulses that bounce off the ocean’s surface and are detected by a sensor on the satellite when they return. Sea surface height derived from satellite altimeters is accurate to within about 3-4 centimeters.

Anomalies in sea level can be identified by calculating the difference between the measured sea surface height and the average sea surface height. By studying sea level anomalies, scientists can improve understanding of ocean circulation patterns and improve forecasts of climatological events such as El Niño and La Niña.

The NOAA Laboratory for Satellite Altimetry produces daily near-real time global sea level anomaly datasets from a constellation of radar altimeter missions. These datasets are now available through CoastWatch/OceanWatch and can be accessed here.


Global map of sea level anomalies for June 26, 2017 produced using the NOAA Laboratory for Satellite Altimetry’s daily near-real time dataset.


References and Related Reading

CryoSat Ground Segment, Instrument Processing Facility L1B, Products Specification Format, ESA: CS-RS-ACS-GS-5106, Issue: 6.4, April 2015.

CryoSat Product Handbook, April 2012.

Jason-3 Product Handbook, SALP-MU-M-OP-16118-CN, edition 1.2. Feb. 2016.

Leuliette, E. W., and R. Scharroo (2010). Integrating Jason-2 into a Multiple-Altimeter Climate Data Record. Marine Geodesy, 33(1), 504517. doi:10.1080/01490419.2010.487795

OSTM/Jason-2 Products Handbook, CNES: SALP-MU-M-OP-15815-CN EUMETSAT: EUM/OPS-JAS/MAN/08/0041 JPL: OSTM-29-1237: NOAA/NESDIS: Polar Series/OSTM J400, Issue: 1 rev 10, October, 2016,

SARAL/AltiKa Products handbook, SALP-MU-M-OP-15984-CN, edition 2.5. July 2016.

Scharroo, R., E. Leuliette, M. Naeije, C. Martin-Puig, and N. Pires (2016), RADS Version 4: An Efficient Way to Analyse the Multi-Mission Altimeter Database, Living Planet Symposium, Proceedings of the conference held 9-13 May 2016 in Prague, Czech Republic. Edited by L. Ouwehand. ESA-SP Volume 740, ISBN: 978-92- 9221-305- 3.

Sentinel-3 User Handbook, ESA: GMES-S3OP-EOPG-TN-13-0001, Issue 1, September 2013.