GOT-e: the Goddard/Grenoble Ocean Tide Model, Extended

The Goddard/Grenoble Ocean Tide (GOT) empirical model, maintained by Richard Ray at NASA-Goddard Space Flight Center, is widely used to remove barotropic ocean tides from satellite altimetry data. GOT is distributed as a set of tidal harmonic constants on a 1/2-degree grid. The smooth tidal fields in GOT are appropriately represented by the 1/2-degree grid; however, the grid does not extend to the shoreline everywhere, making it problematic to utilize GOT for tidal corrections in the coastal zone.

The tar files, below, contain GOT-compatible grids which have been extended to the shoreline by smoothly extrapolating the GOT model. The extrapolated model is referred to as GOT-e to distinguish it from the original model from which it is derived. Note that no new information has been added to GOT, so GOT-e is not more accurate than the original. The fields have been extended by extrapolating the real and imaginary components of the harmonic constants by solving Laplace's equation on land nodes. Neumann boundary conditions are used on the landward edge of the extrapolated zone. Note that the grid has been extended only enough to cover the shoreline, null values occur futher inland.

Download

GOT-e 4.7 Ocean Tide

GOT-e 4.7 Ocean+Load Tide

GOT-e 4.10c Ocean Tide

GOT-e 4.10c Ocean+Load Tide

Acknowledgement

The GOT4.7 and 4.10c models were provided by Richard Ray, NASA-GSFC. The extended versions were prepared with support from the National Geospatial Agency (Award #HM0177-13-1-0008, "Improving Coastal Marine Gravity").