tidal_forcing module reference¶

Detailed Description¶

Tidal forcing¶

Code by Robert Hallberg, August 2005, based on C-code by Harper Simmons, February, 2003, in turn based on code by Brian Arbic.

The main subroutine in this file calculates the total tidal contribution to the geopotential, including self-attraction and loading terms and the astronomical contributions. All options are selected with entries in a file that is parsed at run-time. Overall tides are enabled with the run-time parameter ‘TIDES=True’. Tidal constituents must be individually enabled with lines like ‘TIDE_M2=True’. This file has default values of amplitude, frequency, Love number, and phase at time 0 for the Earth’s M2, S2, N2, K2, K1, O1, P1, Q1, MF, and MM tidal constituents, but the frequency, amplitude and phase ant time 0 for each constituent can be changed at run time by setting variables like TIDE_M2_FREQ, TIDE_M2_AMP and TIDE_M2_PHASE_T0 (for M2).

In addition, approaches to calculate self-attraction and loading due to tides (harmonics of astronomical forcing frequencies) are provided. TIDAL_SAL_FROM_FILE can be set to read the phase and amplitude of the tidal SAL. USE_PREVIOUS_TIDES may be useful in combination with the scalar approximation to iterate the SAL to convergence (for details, see [7]). With TIDAL_SAL_FROM_FILE or USE_PREVIOUS_TIDES, a list of input files must be provided to describe each constituent’s properties from a previous solution. The online SAL calculations that are functions of SSH (rather should be bottom pressure anmoaly), either a scalar approximation or with spherical harmonic transforms, are located in MOM_self_attr_load.