DOI: 10.5281/zenodo.7305418
title: Model setup and output for 'Tidal conversion and dissipation at steep topography in a channel poleward of the critical latitude'

description: Data supplement to Hughes and Klymak 2019

Model input and output in a reduced form associated with the following paper:

Tidal conversion and dissipation at steep topography in a channel poleward of the critical latitudeJournal of Physical Oceanography. doi:10.1175/JPO-D-18-0132.1

Inputs

As described in Table 1 of the associated paper, there are three main sets of simulations. The input files for these sets are contained in their respective directories (`vary_width`, `vary_forcing`, and `vary_freq`). The python script that creates all of the necessary files is `gendata.py`. A fourth directory is titled `baroclinic_terms` and includes that simulation in which u' and p' are output at high temporal resolution.

A key point regarding the input files is that for the vary width and vary forcing cases, a single simulation involves multiple channels. This lets me compile a single executable `mitgcmuv` with a Nx × Ny grid of 600 × 1280, which I divide up into the necessary number of channels by putting vertical walls in appropriate places. For the vary width cases, the 'narrow' simulations are all channels from 0.2 to 32 km and the 'wide' simulations are all wider channels. Once the simulation has run, I use netcdf tools (`ncks`) to extract the individual channels using the scripts in the `extract_scripts` directory.

Most of the files in the `code` directories will be familiar to anyone that uses the MITgcm. An exception is the `energy_diagnostics_fill.F` (and `diagnostics_main_init.F` and `do_statevars_diags.F`, which have minor additions). The original, from `https://github.com/jklymak/MITgcmcode`, was modified slightly to suit this project.

Outputs

The results directory contains five subdirectories to be described in turn.

Notes that in all cases, energy terms in the netCDF files do not include a factor of ρ. This was added in at the plotting stage.

All simulations used Checkpoint67b and were run on Graham: https://docs.computecanada.ca/wiki/Graham.

vary_width

The majority of the files are of the form `obstacle_FFF_YY.nc` where `FFF` is $1000 ω/f$ and `YY` is the channel width in kilometres. These files contain the tidally averaged, depth-integrated energy diagnostics for the seventh tidal cycle at all points (x, y) within the energy control volume.

There are also three files entitled `tophat_995_YY.nc`, which contain fields of U, V, and T (which gives density with α = 0.0002) at two levels. These fields are used as examples for weakly and strongly responding channels.

vary_forcing

These files are of the form `forcing_UU.nc` where `UU` is the deep-water tidal current amplitude U_0 in cm/s. They contain the same energy terms as for the vary width simulations.

vary_freq

These files are of the form `freq_FFF_fields.nc` and contain fields of U, V, and T at two levels. Energy terms are not included because the vary frequency simulations were only run to get estimates of the along-ridge wavelength.

baroclinic_terms

The single file within this directory contains u' and p' at a single x position every five minutes for four tidal cycles.

gaussian_26

This directory, named for its obstacle and width, contains U, V, and T at every grid point for a snapshot in time and another file with the corresponding snapshots of all energy terms.