Python functions for converting polar stereographic coordinates.
This repository contains conversion functions between longitude/latitude and generic x, y (km) coordinates. There are also conversion functions between longitude/latitude and i, j grid coordinates for specific datasets for AMSR-E and SSM/I.
This repository is fully supported by NSIDC. If you discover any problems or bugs, please submit an Issue. If you would like to contribute to this repository, you may fork the repository and submit a pull request.
See the LICENSE for details on permissions and warranties. Please contact nsidc@nsidc.org for more information.
- Python 3.6 or higher (tested with 3.6.7 and 3.9.7)
numpy(python library)
These requirements are also included in the provided environment.yml file,
which can be used with conda to install the
requirements into a conda environment.
To install polarstereo-lonlat-convert-py, clone this repo and then run:
pip install --editable /path/to/cloned/polarstereo-lonlat-convert-py
This will install the polar_convert package in an 'editable' development mode,
allowing you to make changes to the source code in
/path/to/cloned/polarstereo-lonlat-convert-py. See pip's
documentation
for more information.
See the docstrings for individual functions in
polar_convert.py for details. The
functions defined in this file can be used in your own projects.
Convert from geodetic longitude and latitude to Polar Stereographic (X, Y)
coordinates in km. Functional equivilient of
mapll.for.
>>> from polar_convert.constants import NORTH
>>> from polar_convert import polar_lonlat_to_xy
>>> longitude = 20 # longitude in degrees
>>> latitude = 80 # latitude in degrees
>>> true_scale_lat = 70 # true-scale latitude in degrees
>>> re = 6378.137 # earth radius in km
>>> e = 0.01671 # earth eccentricity
>>> hemisphere = NORTH
>>> polar_lonlat_to_xy(longitude, latitude, true_scale_lat, re, e, hemisphere)
[370.2450347527368, -1017.2398726483362]
Convert from Polar Stereographic (x, y) coordinates to geodetic longitude and
latitude. Functional equivilent of
mapxy.for.
>>> from polar_convert.constants import NORTH
>>> from polar_convert import polar_xy_to_lonlat
>>> x = 370.25 # x coordinate in km
>>> y = -1017.24 # y coordinate in km
>>> true_scale_lat = 70 # true-scale latitude in degrees
>>> re = 6378.137 # earth radius in km
>>> e = 0.01671 # earth eccentricity
>>> hemisphere = NORTH
>>> polar_xy_to_lonlat(x, y, true_scale_lat, re, e, hemisphere)
[20.000244645773623, 79.99998329186566]
Convert from longitude and latitude to NSIDC Polar Stereographic I, J (grid) coordinates.
>>> from polar_convert.constants import NORTH
>>> from polar_convert import polar_lonlat_to_ij
>>> longitude = 45 # longitude in degrees
>>> latitude = 85 # latitude in degrees
>>> grid_size = 6.25 # in km
>>> hemisphere = NORTH
>>> polar_lonlat_to_ij(longitude, latitude, grid, hemisphere)
[703, 936]
Convert from NSIDC Polar Stereographic I, J (grid) coordinates to longitude and latitude.
>>> from polar_convert.constants import NORTH
>>> from polar_convert import polar_ij_to_lonlat
>>> i = 10 # `i` is an int representing the x grid coordinate
>>> j = 200 # `j` is an int representing y grid coordinate
>>> grid_size = 12.5 # in km
>>> hemisphere = NORTH
>>> polar_ij_to_lonlat(i, j, grid, hemisphere)
[183.02869857834057, 45.89915728375587]
See DEVELOPMENT.md for information on how to contribute to this python code.
See LICENSE, unless otherwise stated in the README file with each subdirectory.
See Code of Conduct.
This software was developed by the NASA National Snow and Ice Data Center Distributed Active Archive Center.
Author: Chris Torrence, September 2019