SLA 1Hz Products

Alongtrack Sea Level Anomalies - Regional Products


NEWS 2017 :

  • Last release in October 2017
  • Extension of JASON-2 time series, up to october 2017
  • New data editing rules that reduce the RMS of the SLA near the coast and improve the correlation with tide gauges


The CTOH computes and distributes specific, coastal along-track sea level anomalies (SLA) using its X-TRACK processor for all precise altimeter missions : Topex/Poseidon (TP), Jason-1 (J1) , Jason-1 interleaved (J1N), Topex/Poseidon interleaved (TPN), Jason-2, Geosat Follow on (GFO) and Envisat (click here to view available missions and the temporal coverage of each one).


Using the latest corrections available in the CTOH database, CTOH computes a coastally-adapted Sea Surface Height (SSH) along the satellites ground-track for each cycle. Additionnal geophysical corrections are applied accounting for the aliasing of tides and short-term atmopheric effects in the SSH measurements. Details on selected corrections are given here. The Mean Sea Surface (MSSH) is computed at each point, based on the mission period currently available, and subtracted from the corrected SSH in order to form the SLA. The SLA are finally projected onto a reference track with a spatial interval of about 7 km between points (1 second).

For every region highlighted on the map below, the CTOH distributes both the raw SLA and a 40-km along-track filtered SLA product (click on the map to view regional details).



Please do not forget to mention the following sentence in all publications or communications referring to a work based on the CTOH/LEGOS altimetry dataset:

"Altimetry data used in this study were developed, validated, and distributed by the CTOH/LEGOS, France".

 A DOI (Digital Object Identifier) is now attached to X-TRACK products; please use it when referring to it in publication


Data use conditions

Data release: (Coastal data request form)
  • CTOH_X-TRACK_2015_01
  • CTOH_X-TRACK_2017_01
  • CTOH_X-TRACK_2017_02
 Click on the zone you want to view details and informations in this region.

World map of X-TRACK regional polygons (from 2016)

short name long name
adelie Adelie-Mertz
amazon Amazon 
asa  Atlantic South America 
chinasea  China Sea
drake  Drake passage 
eaustralia  East Australia
gom  Gulf of Mexico - Caribbean Sea
gulfstream  Gulf Stream
hudson  Hudson Bay
humboldt  Humboldt current
kerguelen  Kerguelen Islands 
labrador  Labrador Sea 
medsea  Mediterranean Sea 
nea  North East Atlantic 
nindian  North Indian Ocean 
norway  Norway 
nwa  North West America 
nwp  North West Pacific 
sea  South and East Africa 
wafrica  West Africa
waustralia  West Australia
wla  West Latin America - California 
wtp  West Tropical Pacific

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