Tidal correction computation

 

 

Because of the aliasing of tides in the altimeter measurements (Le Provost, 2001), CTOH coastal sea level anomaly products are provided including a so-called tidal correction. Within the CTOH processing (Roblou et al, 2011), state-of-the-art tidal models (e.g. FES2004 (1) from Lyard et al, 2006 and GOT4.7 from Ray et al., XXXX) are used to compute this correction for all missions and over every regions.
In addition, where possible, CTOH computes and removes tidal effects from a specific, regional model simulation based on Mog2D/T-UGOm 2D
model (2). With respect to the tidal correction computed from global models, the tidal correction derived from the regional models make the most of an increased spatial resolution, regional bathymetry solutions and coastlines, and other specific features to provide a better precision in the tidal height prediction over shelves and coastal seas, and are strongly recommended for use.

Tidal corrections are delivered also in a separate field in case of users want to use another tidal correction.

Further details on tidal spectra:

  • The tidal spectrum implemented for the tidal correction based on the FES2004 model solutions includes astronomic constituents M2, S2, N2, K2, K1, 01, Q1, 2N2, P1, Mf, Mm, Mtm and MSqm.  Semi-diurnal constituents Mu2, Nu2, L2, T2, lambda2, KJ2 and R2, diurnal constituents OO1, J1, Phi1, Pi1, Psi1, Ro1, Sigma1, Theta1, 2Q1, Ki1 and long-period constituents MSm, MSf, Mqm, MStm are added using admittances function. Finally, non linear constituent M4, long-period constituent Ssa and radiational S1 constituents are also included.
  • The tidal spectrum implemented for the tidal correction based on GOT4.7 includes the same tidal constituents as FES2004, with the exception of S1.
  • The tidal spectra implemented for the tidal correction based on regional tidal Mog2D/T-UGOm 2D models include basically the same tidal constituents as included in the FES2004 spectrum. Non linear additional constituents (e.g. MS4, S4, MN4, N4) may be included depending on the region.

 

 



References:

Roblou L., J. Lamouroux, J. Bouffard, F. Lyard, M. Le Hénaff, A. Lombard, P. Marsalaix, P. De Mey and F. Birol (2011) : Post-processing altimiter data towardcoastal apllications and integration into coastal models. Chapter 9 in S. Vignudelli, A.G Kostianoy, P. Cipollini, J. Benveniste (eds.), Coastal Altimetry, Springer Berlin Heidelberg.

Le Provost C. (2001) : Ocean tides. In: Fu LL, Cazenave A (eds) Satellite altimetry and earth sciences: a handbook of techniques and applications. Int Geophys Ser, vol 69. Academic, San Diego, CA, pp 267–303

Lyard F., F. Lefèvre, T. L etellier, O. F rancis (2006) : Modelling the global ocean tides: modern insights from FES2004, Ocean Dynamics, xxx. 10.1007/s10236-006-0086-x.

Ray R.D. (2008) : Thoughts on Sahllow-Water Tides ans Altimetry, Coastal Altimetry Workshop, Silver Spring, Maryland February 5-7.

Roblou L. (2004) : Validation des solutions de marée en Mer Méditerranée: comparaisons aux observations, Technical Report, POC-TR-02-04, 67pp, Pôle d’Océanographie Côtière, Toulouse, France

Maraldi C. , B. G. Alton-Fenzi , F. Lyard , C. E. Testut , R. Coleman (2007) : Barotropic tides of the Southern Indian Ocean and the Amery Ice Shelf cavity. Geophys. Res. Let. , 34, XX. 10.1029/2007GL030900.

Pairaud I.L., F. Lyard, F. Auclair, T. Letellier, P. Marsalaix (2008), Dynamics of the semi-diurnal and quarter-diurnal internal tides in the Bay of Biscay. Part1: Barotropic tides, Continental Shelf Research, 28, 1294-1315.

Le Bars Y., F. Lyard, C. Jeandel, Leonardo Dardengo (2010) : The AMANDES tidal model for the Amazon estuary and shelf. Ocean Modelling, DOI: 10.1016/j.ocemod.2009.11.001.


(1) FES2004 tidal atlas is freely available on request on the LEGOS web site: http://www.legos.obs-mip.fr/en/share/soa/cgi/getarc/v0.0/index.pl.cgi?contexte=SOA&donnees=maree&produit=modele_fes
(2) Regional tidal atlases are freely available on request on the SIROCCO web site: http://sirocco.omp.obs-mip.fr/outils/Tugo/Produits/TugoProduits.htm

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