A Python package for creating SCHISM boundary condition forcing and hotstart files from ROMS output
Project description
ROMS2SCHISM
A Python package for creating SCHISM boundary condition forcing and hotstart files from ROMS output.
The roms2schism
module contains four main sub-modules:
schism
: for loading the SCHISM grid (e.g.hgrid.ll
,vgrid.in
)boundary
: for creating "type 4" SCHISM boundary conditions (uv3D.th.nc
etc. files) from ROMS outputnudging
: for creating temperature and salinity nudging files for the open boundary (TEM_nu.nc
andSAL_nu.nc
) from ROMS outputhotstart
: for creating hotstart initial conditions (hotstart.nc
) from ROMS output
Loading the SCHISM grid
The SCHISM grid can be loaded like this:
import roms2schism as r2s
schism = r2s.schism.schism_grid(schism_grid_file, schism_vgrid_file, schism_grid_dir, lonc, latc)
The defaults for the parameters are:
schism_grid_file
:hgrid.ll
schism_vgrid_file
:vgrid.in
schism_grid_dir
:./
lonc
,latc
:None
The lonc
, latc
parameters define a reference longitude and latitude, used to convert the horizontal grid coordinates (assumed to be longitude, latitude) to an approximate projected coordinate system. If these are not specified, default values are calculated by averaging the grid vertex coordinates.
Creating boundary conditions
Boundary conditions can be created like this:
r2s.boundary.make_boundary(schism, template, dates, start, end, roms_dir,
roms_grid_filename, roms_grid_dir, dcrit)
The schism
parameter is the SCHISM grid created above.
The template
and dates
parameters are used to define the sequence of filenames for the ROMS files used to create the boundary conditions. The dates
parameter is an array of datetime
objects. These are processed using the template
string to create the filenames. All the ROMS date files must be in the directory specified by roms_dir
.
The start
and end
parameters define the start and end datetimes
of the simulation. Boundary conditions are created from ROMS results between these datetimes. They both default to None
, in which case they are set equal to the first and last datetimes in the ROMS results.
The roms_grid_filename
and roms_grid_dir
parameters can be used to specify a ROMS grid file. This may be needed if the ROMS results do not contain the u_eastward
and v_northward
fields, in which case they are reconstructed (rotated and de-staggered) from the u
and v
fields. Otherwise, these parameters do not need to be specified.
The dcrit
parameter specifies a critical distance used to avoid interpolating ROMS results over land. It should generally be slightly larger than the ROMS grid resolution. If SCHISM grid points are further than this distance from the nearest ROMS grid point, nearest neighbour interpolation is used instead of bilinear interpolation.
Creating nudging files
Nudging files for temperature and salinity can be created like this:
r2s.nudging.make_nudging(schism, template, dates, start, end, roms_dir,
roms_grid_filename, roms_grid_dir, dcrit)
The parameters for nudging are the same as those for creating the boundary conditions. The only difference is that typically nudging files are created from time-averaged ROMS results (e.g. daily averages), so the template
parameter will be different.
Creating hotstart initial conditions
Hotstart files can be created like this:
r2s.hotstart.make_hotstart(schism, roms_data_filename, start, roms_dir,
roms_grid_filename, roms_grid_dir, dcrit, h0)
For the initial conditions, only one ROMS data file is needed, specified via the roms_data_filename
parameter. Most of the other parameters are the same as for creating boundary conditions and nudging. The h0
parameter (default 0.01 m) specifies the water depth below which SCHISM nodes will be considered dry at the start of the run.
Example
from datetime import datetime, timedelta
import numpy as np
import roms2schism as r2s
# set up dates corresponding to ROMS files to be read:
start_filedate = datetime(2017, 1, 1)
ndays = 30
dates = start_filedate + np.arange(ndays) * timedelta(days = 1)
start_date = datetime(2017, 1, 12)
roms_dir = '/path/to/roms/data/'
dcrit = 7e3 # should be slightly larger than ROMS grid resolution
# read SCHISM grid:
schism = r2s.schism.schism_grid()
# create boundary forcing files:
template = "foo_his_%Y%m%d.nc"
r2s.boundary.make_boundary(schism, template, dates, start_date,
roms_dir = roms_dir, dcrit = dcrit)
# create boundary nudging files for T, S:
template = "foo_avg_%Y%m%d.nc"
r2s.nudging.make_nudging(schism, template, dates, start_date,
roms_dir = roms_dir, dcrit = dcrit)
# create hotstart.nc file:
roms_data_filename = "foo_his_20170101.nc"
r2s.hotstart.make_hotstart(schism, roms_data_filename, start_date,
roms_dir = roms_dir, dcrit = dcrit)
Installation
ROMS2SCHISM can be installed from PyPI via pip
:
pip install roms2schism
Project details
Release history Release notifications | RSS feed
Download files
Download the file for your platform. If you're not sure which to choose, learn more about installing packages.
Source Distribution
Built Distribution
Hashes for roms2schism-0.9.1-py3-none-any.whl
Algorithm | Hash digest | |
---|---|---|
SHA256 | c028492f8dd29ba217137bcdcd59eb6529b36cfcfb158440ed80ca0902f1e7e0 |
|
MD5 | 80788627ae4c472cb16b23708a6382fb |
|
BLAKE2b-256 | 8fda21ad6780eda23ad3a6fe19575d13df71e253bb66ffb377a4b46f987bd7ca |