Utilities for converting polar stereographic coordinates.
To access the legacy IDL or Fortran version of these tools, see polar_stereo_legacy.
NSIDC's polar stereographic projection specifies a projection plane or grid tangent to the Earth's surface at 70° northern and southern latitude. While this increases the distortion at the poles by six percent and decreases the distortion at the grid boundaries by the same amount, the latitude of 70° was selected so that little or no distortion would occur in the marginal ice zone.
This repo contains conversion routines between longitude/latitude and generic x, y (km) coordinates. There are also conversion routines between longitude/latitude and i, j grid coordinates for specific datasets for AMSR-E and SSM/I.
See also Polar Stereo Overview.
- 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.
- Python 3.6 or higher (tested with 3.6.7)
- numpy (python library)
- cartopy (python library)
- pyhdf (python library)
- HDF4 (on unix, this would be a package such as libhdf4-dev)
No special installation is needed, other than installing the above requirements.
See the individual files for details. The utilities in these files can be used in your own projects.
polar_convert.py:
Convert from longitude, latitude to Polar Stereographic x, y (km) and vice versa.
polar_lonlat_to_xy replaces Fortran mapll.for
polar_xy_to_lonlat replaces Fortran mapxy.for
nsidc_polar_lonlat.py: Transform from longitude and latitude to NSIDC Polar Stereographic I, J (grid) coordinates.
nsidc_polar_ij.py: Transform from NSIDC Polar Stereographic I, J (grid) coordinates to longitude and latitude.
read_mask: Read in a Polar Stereographic mask file and return the data.
read_mask_hdf: Read in an HDF4 Polar Stereographic mask file and return the data.
display_mask: Read in and display a Polar Stereographic mask file.
See LICENSE
See Code of Conduct.
This software was developed by the National Snow and Ice Data Center with funding from multiple sources.