High-resolution coastlines

You can get high-resolution coastlines in your PyNGL maps if you download and install the multi-resolution coastline database RANGS (Regionally Accessible Nested Global Shorelines), developed by Rainer Feistel from Wessel and Smith's GSHHS (Global Self-consistent Hierarchical High-resolution Shoreline) database.

To use this database, you must first download it from Rainer Feistel's website. Somewhere on this page you should see a table with ten *.zip files to download:

 
    rangs(0).zip     gshhs(0).zip
    rangs(1).zip     gshhs(1).zip
    rangs(2).zip     gshhs(2).zip
    rangs(3).zip     gshhs(3).zip
    rangs(4).zip     gshhs(4).zip

You must download all ten of these files, unzip them, and either put them in the expected default directory:

   $PYTHONPATH/lib/pythonx.y/site-packages/ngl/ncarg/rangs/

For older installations of PyNGL:

    $PYTHONPATH/lib/pythonx.y/site-packages/PyNGL/ncarg/rangs/

You can also put them in your own preferred directory, but then you must set the environment variable PYNGL_RANGS to this directory.

The files take up about 140 megabytes, unzipped. $PYTHONPATH is being used above only to indicate the path leading up to your python installation, and not as actual text. You will need to replace $PYTHONPATH with the actual directory where python resides on your system, like "/usr/local".

Note that it is possible that after you unzip the files, the rangs(n).cat and rangs(n).cel files will get put in their own subdirectories. If this happens, you will need to move these files so they are in the same directory as the gshhs(n) files.

Once you have the files in the appropriate location, then in your PyNGL script, you can set the map resource mpDataBaseVersion = "HighRes" to create maps using this database. Note: you should not use this database to plot maximal area plots, because 1) you will get horizontal lines through your plot, and 2) it takes a long time.

Examples

• coast1.py (output)