Ocean tide models

The empirical ocean tide models are developed within the COTAGA project.

EOT11a

EOT11a is the latest empirical ocean tide model obtained by residual tidal analysis of multi-mission-altimetry data at the DGFI. The model includes the long-period tides Mm and Mf, the main astronomical tides M2, S2, N2, K2, 2N2, O1, K1, P1 and Q1, the non-linear constituent M4, as well as the radiational tide S1. The corresponding data (in-phase and quadrature grids) and documentation can be accessed via the DGFI FTP server. The tide model is also published in spherical harmonics representation, additionally including long-period tides Om1, Om2, Sa, Ssa, Mtm and Msqm. For quick tidal predictions with the EOT11a model, we provide the data together with MATLAB routines as a compressed .zip-File EOT11a.zip (note that the radiational tide S1 is not included!). The spherical harmonics representation and MATLAB routines are described in detail within the supplementary Technical Note. Alternatively, EOT11a is published in accordance to the format description of the IERS conventions 2010. A video of the model is also available in the media section.

EOT11ag

EOT11ag is an update of the altimetry-based EOT11a model. It additionally contains information of residual ocean tides estimation from GRACE. For this purpose, ten years of GRACE observations are used to solve for the eight major tidal constituents M2, S2, N2, K2, K1, O1, Q1 and P1. The combination is based on the full normal equation system of the GRACE solutions and the respective weighting between GRACE and altimetry is iteratively derived be means of variance component estimation. Apart from the updated eight major tides, this model includes the same tidal constituents as already published in EOT11a. EOT11ag is provided as compressed  .zip-File EOT11ag.zip in spherical harmonics representation together with MATLAB routines for evaluation (see Technical Note for EOT11a), or in IERS 2010 format

References

T. Mayer-Gürr, R. Savcenko, W. Bosch, I. Daras, F. Flechtner, Ch. Dahle, Ocean tides from satellite altimetry and GRACE, Journal of Geodynamics, Volumes 59–60, September 2012, Pages 28-38, ISSN 0264-3707, http://dx.doi.org/10.1016/j.jog.2011.10.009. Petit G. and Luzum B., editors. IERS Conventions (2010). IERS Technical Note No. 36. Verlag des Bundesamts für Kartographie  und Geodäsie, Frankfurt am Main, 2010. Barthelmes F. and Förste C. The ICGEM-format. Technical report, GFZ Potsdam, Department 1 Geodesy and Remote Sensing, June 2011.