Date: September 4, 2026
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Contact: S. Desai (shailen.desai@jpl.nasa.gov)

This package provides geopotential coefficients for the self-consistent
equilibrium ocean pole tide admittance.

They represent the self-consistent equilibrium ocean pole tide admittance model
described in Desai et al. (2015). In turn, these values are an updated
version of the model values described in Desai (2002). Explanations of the
model update from Desai (2002) to Desai et al. (2015) are described in Desai et al. (2015).

This (Desai et al., 2015) update uses Green's functions from Guo et al. (2004)
and a 0.1 degree latitude/longitude resolution land/ocean mask that is based
upon the TPXO8 ocean tide model (Egbert el al., 2002).

Four files are provided with this REAMDE file.

desaietal2015_scopole_coef.txt - The model coefficients of the Desai et al. (2015)
                         self-consistent equilibrium ocean pole tide admittance
                         that are required to compute the perturbations to the
			 geopotential coefficients from the ocean pole tide.
			 These coefficients should simply be inserted into
			 the equations provided in the IERS standards to
			 generate the normalized geopotential coefficients.
                         The coefficients are provided in the same format as 
                         was provided from the Desai (2002) model. Users should
                         therefore be able to swap out the model coefficients.
                         Refer to IERS standards for explicit equations to
                         to use these coefficients.

desai2015_scopole_2004.txt - Example of a time series of the normalized C21 and
			 S21 geopotential coefficients from the ocean pole tide for
                         the time period Jan 1, 2004 to Dec 31, 2004.
			 This file also provides values of the various
			 contants, pole locations, and mean pole location
			 that were used to compute this time series.
                         WARNING: This example uses the current definition of the
                         mean pole location, and is different to that used in the
                         similar example file provided with the Desai (2002) coefficients.

desai2002_scopole_2004_oldmeanpole.txt - This example C21/S21 time series should be the exact 
                         file provided to IERS with the Desai (2002) coefficients, 
                         but using the old definition of the mean pole.

desai2015_scopole_2004_oldmeanpole.txt - This example C21/S21 time series uses the
                         Desai (2015) coefficients, but using the old definition of the
                         mean pole. This time series can be compared to that in
                         desai2002_scopole_2004_oldmeanpole.txt to evaluate the
                         impact on C21/S21 coefficients from Desai et al. (2015)
                         versus Desai (2002).

The normalization of the geopotential coefficients is as used in the IERS conventions.

NOTES: 
1) The pole location time series provided in each of the examples above should not
   be considered to be representing current estimates of the pole location. Recent
   estimates of the pole location are likely to be different. The pole locations in the
   example files are only provided to allow a user to verify correct implementation of the
   pole tide coefficients with those specific pole locations.
   Thereafter, the user is responsible for choosing their preferred values
   of the various constants required to compute the geopotential.
2) The user should choose their preferred values of load Love numbers (k') when applying
   these coefficients. The Guo et al. (2004) Green's functions were only used to derive
   the admittance coefficients provided in desaietal2015_scopole_coef.txt. Here again,
   values in the example files are there only to validate correct implementation of the
   coefficients.
   Thereafter, the user is responsible for choosing their preferred values
   of the various constants required to compute the geopotential.

Citation:
Please cite Desai et al. (2015) when using the provided coefficients.

References:
Desai, S. D., Observing the pole tide with satellite altimetry, J. Geophys. Res., 107 (C11), 3186,
doi:10.1029/2001JC001224, 2002, https://doi.org/10.1029/2001JC001224.

Desai, S., Wahr, J. and Beckley, B., Revisiting the pole tide for and from satellite altimetry, 
J. Geodesy, 89, 1233-1243, 2015, https://doi.org/10.1007/s00190-015-0848-7.

Egbert, G. D., Erofeeva, S. Y., Efficient inverse modeling of barotropic ocean tides, J. Atmos.
Oceanic Technol., 19:183-204, 2002, https://doi.org/10.1175/1520-0426(2002)019<0183:EIMOBO>2.0.CO;2.

Guo, J. Y., Li, Y. B., Huang, Y., Deng, H. T., Xu, S. Q., and Ning, J. S., Green's function
of the deformation of the Earth as a result of atmospheric loading, Geophy. J. Int., 159:53-68,
2004, https://doi.org/10.1111/j.1365-246X.2004.02410.x.

IERS Conventions Website: https://www.iers.org/iers/en/dataproducts/conventions/conventions

Acknowledgement:
The work represented here was performed at the Jet Propulsion Laboratory, California Institute
of Technology under a contract with the National Aeronautics and Space Administration.
