Readers for input data

2.3. Readers for input data#

Several types of data are used to prepare files for CROCO realistic simulations:

  • topographic/bathymetric data to build the model bathymetry

  • 3D ocean data (generally from another (re-)analysis) to build the initial and boundary conditions

  • tidal harmonics to build the tidal forcing

To read these data, depending on their own formatting, the toolbox uses the configuration file readers.jsonc.

Several readers are already implemented, but you can add any other reader for managing your input data if needed.

Note

Several readers are designed for “homemade preprocessed data” inherited from croco_tools and available in example datasets provided along with CROCO (e.g. etopo2, cfsr, mercator_croco…)

2.3.1. Topography : section “Topo” of readers.jsonc file#

Input data needed by the tools must be in netcdf format. The extensions of the files could be .nc or .grd.

To build bathymetry from a netcdf file, the dictionnary needs at least four keys:

lon

Longitude

lat

Latitude

topo

Name of the 2-D bathymetric field

zaxis

Direction of z axis (up or down)

Warning

A supplementary key srtm needs to be added and set to True if the input dataset is STRM30plus

2.3.2. Initial and boundary conditions: section “IBC” of readers.jsonc file#

Reader for initial and boundary conditions (ibc) handles 2D and 3D fields and their evolution in time. It requires their coordinates:

depth

Z-coordinates variables

lonr, lonu, lonv

Longitude name for Rho,U,V grid. If only one grid put the same name everywhere

latr, latu, latv

Latitude name for Rho,U,V grid. If only one grid put the same name everywhere

time, time_dim

Time variable and the associated time dimension

And the following fields:

ssh

Sea Surface Elevation variable name

u

Eastward velocity (m/s) variable name

v

Northward velocity (m/s) variable name

temp

temperature (C) variable name

salt

salinity (PSU) variable name

You can also add other tracers if needed following the same pattern:

"temp": "thetao",
"salt": "so",
"tracer": "tracer_name_in_dataset",

2.3.3. Tides: section “Tides” of readers.jsonc file#

First the keys for geographical coordinates are specified:

lonr, lonu, lonv

Longitude name for Rho, U, V grid. If only one grid put the same name everywhere

latr, latu, latv

Latitude name for Rho, U, V grid. If only one grid put the same name everywhere

Tide data consist in three fields (elevation, easwtward velocity, northward velocity), and each field has two components. Depending on the input dataset, those two components can be either Amplitude/Phase (like FES) or Real/Imaginary part (like TPXO).

If your dataset follows an Amplitude/Phase, keys to declare are:

H_a

Elevation amplitude

H_p

Elevation phase

U_a

Eastward velocity amplitude

U_p

Eastward velocity phase

V_a

Northward velocity amplitude

V_p

Northward velocity phase

Or if it follows a Real/Imaginary format, keys to declare are:

H_r

Elevation real part

H_i

Elevation imaginary part

U_r

Eastward velocity real part

U_i

Eastward velocity imaginary part

V_r

Northward velocity real part

V_i

Northward velocity imaginary part

Some datasets like TPXO follow a complex a-b*i convention. You therefore need to pay attention to the sign when calculating the phase. A flag for the phase is thus provided:

invert_phase

true/false flag. True when need to revert the phase (e.g. TPXO case)

In addition, for some datasets, like TPXO, U and V are given as transport. To convert them to velocities, the depth is required, thus additional variables are provided in the reader:

topor, topou, topov

depth name for Rho, U, V grid. If only one grid put the same name everywhere
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