DEALIASING PRODUCTS

The ERA-Interim/TUGO dealiasing products contain the time-variable 3D gravitational potential of the atmosphere and ocean masses. A mean value of the original grids based on 10 years of data (2001-2010) has been subtracted from the time series, therefore these products represent only the time-variable part of the atmosphere and ocean masses attraction.

They were computed from:

  • The ERA-interim reanalysis of ECMWF (60 model levels, every 3 hours ) for the atmospheric part;
  • The TUGO barotropic model (Florent Lyard, LEGOS/CNRS) for the oceanic response to the ERA-interim pressure and wind forcing (every 3 hours).

The computation was performed by Pascal Gégout (GET/CNRS), integrating the gravitational potential at each model level in order to obtain the total gravitational effect outside the atmospheric masses; this is why it is called a « 3D » gravitational potential.

The solid Earth response to this time-variable atmosphere & ocean potential has been taken into account through the use of the kp Love numbers (Gégout P., article in preparation).

Click on the link below to access the dealiasing products (125 Mb/year).

Warning: The password required for accessing this data is: itrf2013

DOWNLOAD HERE : Atmosphere and ocean gravitational potential

Click on the year you want to retrieve (125 Mb/year).

Then:

tar -xvf AOD1B_CNES_YYYY.tar

unzip AOD1B_CNES_YYYY_MM.zip

OCEAN TIDES

The FES2014b (MSf corrected) model is available for download in spherical harmonic coefficients.

The original FES2014b documentation and  1/16° x 1/16° grid files can be found on the AVISO web site.

For use in the orbit computation softwares, the original amplitude and phase grids of FES2014b have been processed in the following way:

  • use of the corrected MSf wave instead of the original one (in the original MSf wave, only the non-linear part of this wave was given, whereas in the corrected MSf wave the complete wave amplitude is given – non-linear and quasi-equilibrium parts)
  • setting tide amplitude to zero on the land areas
  • conversion to spherical harmonics (SH) up to degree and order 100 x 100 for each wave
  • application of an ellipsoidal correction to the SH coefficients in order to pin the water heights to the ellipsoidal surface of the Earth
  • addition of the long-period Om1 and Om2 waves (only the C20 coefficient)
  • removal (or not) of the S1 wave (depending on the ocean dealiasing model used)

Explanation: In the TUGO dealiasing product, the atmospheric S1 wave cannot be distinguished from the astronomic S1 wave, so the TUGO products include the S1 astronomic wave and therefore this wave should not be taken into account in the ocean tide model.

The FES2014b (MSf corrected) ocean tide model in spherical harmonics therefore comes in two versions (with or without S1 wave).

  • FES2014b Spherical harmonics in water height:

FES2014b with S1 wave

FES2014b without S1 wave

  • FES2014b Spherical harmonics in geopotential:

FES2014b with S1 wave

FES2014b without S1 wave