Tidal Constants Products


Alongtrack Tidal Constants - Regional Products


X-TRACK produtcs are now available on aviso+ website



The CTOH computes and distributes tidal constants estimated from its along-track 1Hz sea level anomalies (SLA) products.


SLA time series have been computed with the  X-TRACK processor for the whole TOPEX/Poseidon, Jason-1 and Jason-2 period applying the latest reprocessing CTOH standards. As long-term CTOH SLA time series are distributed onto a reference grid along the satellites ground track, tidal constants are estimated directly by harmonic analysis of each single time series (i.e. every 6.2km).

CTOH tidal constants product contains along-track estimates of amplitude (variable 'amplitude''), phase lag (variable 'phase_lag') for each tidal constituent (variable 'constituentname') that can be recovered locally with CTOH specific harmonic analysis software. Spatial locations of tidal estimates along the altimeter ground track are indicated in 'latitude'  and 'longitude'  variables. Record length of single time series is provided by the 'samples'' variable.

In addition, CTOH tidal constants product contains, for each tidal constituent, two along-track error estimates associated to the tidal constants. One is directly computed from the inverse method theory (variable 'mean_square_error') and the other one is taking into account the ocean background signal at aliased tidal frequencies (variable 'bg_contamination_error').



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".


X-TRACK references

Examples of applications: global FES2012 tide model validation


Data release:

  • CTOH_X-TRACK_Tidal_2015_01
  • CTOH_X-TRACK_Tidal_2018_01

When clicking on the image below you will be redirected to our Aviso+ web page where more information can be found.

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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