Global ocean along-track sea level anomalies


Detailed description:
This product is produced by the CMEMS SL-TAC multimission altimeter data processing system. It serves in near-real time the main operational oceanography and climate forecasting centers in Europe and worldwide. It processes data from all altimeter missions: HY-2A, Saral/AltiKa, Cryosat-2, Jason-2, Jason-1, T/P, ENVISAT, GFO, ERS1/2. It provides a consistent and homogeneous catalogue of products for varied applications, both for near real time applications and offline studies.The temporal coverage for NRT products is fluctuating and depends on updates of Delayed-time products. When Delayed-Time products are updated, the oldest NRT product are replaced by the best quality Delayed-Time products so that the two series are overlapping on few weeks or few months.

Processing information:
To produce SLA in near-real time, the system exploits the most recent datasets available based on the enhanced OGDR+IGDR production. The system acquires and then synchronizes altimeter data and auxiliary data; each mission is homogenized using the same models and corrections.The Input Data Quality Control checks that the system uses the best altimeter data. The multi-mission cross-calibration process removes any residual orbit error, or long wavelength error (LWE), as well as large scale biases and discrepancies between various data flows; all altimeter fields are interpolated at crossover locations and dates. After a repeat-track analysis, a mean profile, which is peculiar to each mission, or a Mean Sea Surface (when the orbit is non repetitive) is substracted to compute sea level anomaly. Data are then cross validated, filtered from residual noise and small scale signals, and finally sub-sampled (Sea level Anomaly product, SLA). The MSS is available via the Aviso+ dissemination ( In order to compute Absolute Dynamic Topography, the Mean Dynamic Topography (MDT) can be added. It is distributed by Aviso+ (

sea surface height ;

Temporal coverage   
2012-12-26 to D+6
temporal resolution: 1day

Geographical coverage
Latitude = -80.0/90.0; Longitude = -180/179.9

Vertical coverage
0.49 – 5727.91

Spatial resolution
14 km

Update frequency


Data access