self_attr_load module reference¶
This module contains methods to calculate self-attraction and loading (SAL) as a function of sea surface height (SSH) (rather, it should be bottom pressure anomaly). SAL is primarily used for fast evolving processes like tides or storm surges, but the effect applies to all motions.
Detailed Description¶
If SAL_SCALAR_APPROX is true, a scalar approximation is applied (Accad and Pekeris 1978) and the SAL is simply
a fraction (set by SAL_SCALAR_VALUE, usually around 10% for global tides) of local SSH . For tides, the scalar approximation can also be used to iterate the SAL to convergence [see USE_PREVIOUS_TIDES in MOM_tidal_forcing, Arbic et al. (2004)].
If SAL_HARMONICS is true, a more accurate online spherical harmonic transforms are used to calculate SAL. Subroutines in module MOM_spherical_harmonics are called and the degree of spherical harmonic transforms is set by SAL_HARMONICS_DEGREE. The algorithm is based on SAL calculation in Model for Prediction Across Scales (MPAS)-Ocean developed by Los Alamos National Laboratory and University of Michigan [Barton et al. (2022) and Brus et al. (2023)].
References:
Accad, Y. and Pekeris, C.L., 1978. Solution of the tidal equations for the M2 and S2 tides in the world oceans from a knowledge of the tidal potential alone. Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences, 290(1368), pp.235-266. https://doi.org/10.1098/rsta.1978.0083
Arbic, B.K., Garner, S.T., Hallberg, R.W. and Simmons, H.L., 2004. The accuracy of surface elevations in forward global barotropic and baroclinic tide models. Deep Sea Research Part II: Topical Studies in Oceanography, 51(25-26), pp.3069-3101. https://doi.org/10.1016/j.dsr2.2004.09.014
Barton, K.N., Pal, N., Brus, S.R., Petersen, M.R., Arbic, B.K., Engwirda, D., Roberts, A.F., Westerink, J.J., Wirasaet, D. and Schindelegger, M., 2022. Global Barotropic Tide Modeling Using Inline Self‐Attraction and Loading in MPAS‐Ocean. Journal of Advances in Modeling Earth Systems, 14(11), p.e2022MS003207. https://doi.org/10.1029/2022MS003207
Brus, S.R., Barton, K.N., Pal, N., Roberts, A.F., Engwirda, D., Petersen, M.R., Arbic, B.K., Wirasaet, D., Westerink, J.J. and Schindelegger, M., 2023. Scalable self attraction and loading calculations for unstructured ocean tide models. Ocean Modelling, p.102160. https://doi.org/10.1016/j.ocemod.2023.102160