2022-05-28 BUGFIX
Richard Ray noticed a bug in the software under ./hret_tide/ which produced compiler-dependent results due to an uninitialized variable.
Note: The HRET_v8.1 fields are defined everywhere, including on land and in ocean areas where the phase-locked internal could not be mapped accurately. The prediction software will compute 0.0 tidal elevation at these locations.
Computing tidal predictions with the HRET models:
The HRET models are described here.
The NetCDF files contain real and imaginary parts of the harmonic constants. Thus,
the predicted tide at a particular time, t, may be computed from h(t) = re*cos(omega*t) + im*sin(omega*t),
where time is referenced to the appropriate date, and the frequency of the tide is omega.
For more precision, the nodal modulations of amplitude and phase may be included. The
argument, omega*t, is usually computed directly from the mean longitudes of the relevant astronomical
quantities as a function of the Julian Date or some other time standard for which the mean
longitudes are known.
The software in this repository contains different versions of this computation, which should allow you to compute tidal predictions of individual tidal components, e.g., M2, or form the sum of all the components in the HRET model.
Sub-directories:
./hret_tide/ -- Remko Scharroo's fortran software for the Jason-CS Preprocessor. Received 2019-03-08. This sofware contains everything you need to compute the arguments of the cosine and sine functions for the given times. It also has expressions for the nodal modulation.
./hret_vel/ -- My julia-language software for computing tidal currents at the ocean surface. This software calls my harmonic analysis library
jd_funcs.jl, in the HA repository, to compute the arguments.While I have made every effort to provide accurate information, I urge you to double check the numerical results you compute with this software. Please contact me if you find mistakes in the information presented here.
Be aware that the HRET models are models of the internal tide. The predicted elevations are typically only a few centimeters. For ocean tide predictions at ports and harbors, please see the NOAA website.