# This software is open source software available under the BSD-3 license.
#
# Copyright (c) 2019 Triad National Security, LLC. All rights reserved.
# Copyright (c) 2019 Lawrence Livermore National Security, LLC. All rights
# reserved.
# Copyright (c) 2019 UT-Battelle, LLC. All rights reserved.
#
# Additional copyright and license information can be found in the LICENSE file
# distributed with this code, or at
# https://raw.githubusercontent.com/MPAS-Dev/pyremap/main/LICENSE
import numpy
import pyproj
import xarray
from pyremap.descriptor import ProjectionGridDescriptor
[docs]def get_arctic_stereographic_projection():
"""
Get a projection for an Arctic stereographic comparison grid
Returns
-------
projection : ``pyproj.Proj`` object
The projection
"""
# Authors
# -------
# Milena Veneziani
projection = pyproj.Proj('+proj=stere +lat_ts=75.0 +lat_0=90 +lon_0=0.0 '
'+k_0=1.0 +x_0=0.0 +y_0=0.0 +ellps=WGS84')
return projection
[docs]def get_antarctic_stereographic_projection():
"""
Get a projection for an Antarctic steregraphic grid
"""
projection = pyproj.Proj('+proj=stere +lat_ts=-71.0 +lat_0=-90 +lon_0=0.0 '
'+k_0=1.0 +x_0=0.0 +y_0=0.0 +ellps=WGS84')
return projection
[docs]def get_polar_descriptor_from_file(fileName, projection='antarctic'):
"""
Get a descriptor of a polar stereographic grid used for remapping
Parameters
----------
fileName : str
A file containing x and y coordinates for the grid
projection : {'arctic', 'antarctic', pyproj.Proj}
The projection to use. 'arctic' and 'antarctic' are polar
stereographic projections with reference latitude at +/- 71 degrees
Returns
-------
descriptor : ``ProjectionGridDescriptor`` object
A descriptor of the polar grid
"""
dsIn = xarray.open_dataset(fileName)
x = dsIn.x.values
y = dsIn.y.values
dx = int((x[1] - x[0]) / 1000.)
Lx = int((x[-1] - x[0]) / 1000.)
Ly = int((y[-1] - y[0]) / 1000.)
meshName = '{}x{}km_{}km_Antarctic_stereo'.format(Lx, Ly, dx)
projection = _get_projection(projection)
descriptor = ProjectionGridDescriptor.create(projection, x, y, meshName)
return descriptor
[docs]def get_polar_descriptor(Lx, Ly, dx, dy, projection='antarctic'):
"""
Get a descriptor of a polar stereographic grid used for remapping
Parameters
----------
Lx, Ly : double
Size of the domain in x and y in km
dx, dy : double
Resolution of the grid in km
projection : {'arctic', 'antarctic', pyproj.Proj}
The projection to use. 'arctic' and 'antarctic' are polar
stereographic projections with reference latitude at +/- 71 degrees
Returns
-------
descriptor : ``ProjectionGridDescriptor`` object
A descriptor of the Antarctic grid
"""
upperProj = projection[0].upper() + projection[1:]
meshName = '{}x{}km_{}km_{}_stereo'.format(Lx, Ly, dx, upperProj)
xMax = 0.5 * Lx * 1e3
nx = int(Lx / dx) + 1
x = numpy.linspace(-xMax, xMax, nx)
yMax = 0.5 * Ly * 1e3
ny = int(Ly / dy) + 1
y = numpy.linspace(-yMax, yMax, ny)
projection = _get_projection(projection)
descriptor = ProjectionGridDescriptor.create(projection, x, y, meshName)
return descriptor
[docs]def to_polar(points):
projection = get_antarctic_stereographic_projection()
latLonProjection = pyproj.Proj(proj='latlong', datum='WGS84')
transformer = pyproj.Transformer.from_proj(latLonProjection, projection)
x, y = transformer.transform(points[:, 0], points[:, 1], radians=False)
points[:, 0] = x
points[:, 1] = y
return points
[docs]def from_polar(points):
projection = get_antarctic_stereographic_projection()
latLonProjection = pyproj.Proj(proj='latlong', datum='WGS84')
transformer = pyproj.Transformer.from_proj(projection, latLonProjection)
lon, lat = transformer.transform(points[:, 0], points[:, 1], radians=False)
points[:, 0] = lon
points[:, 1] = lat
return points
def _get_projection(projection):
if isinstance(projection, str):
if projection == 'arctic':
projection = get_arctic_stereographic_projection()
elif projection == 'antarctic':
projection = get_antarctic_stereographic_projection()
else:
raise ValueError('Bad projection name {}'.format(projection))
return projection