This function returns a logical array describing the landness of any given lat/lon arrays. Requires Matlab's Mapping Toolbox.
This function uses Matlab's built-in coast.mat file with inpolygons to determining whether input lat/lons are inside or outside perimeters of land areas.
land = landmask(lat,lon)
land = landmask(...,'landmass')
land = landmask(...,quality)
land = landmask(lat,lon) returns logical land array corresponding to the dimensions of input lat and lon. 1 is land, 0 is not land.
land = landmask(...,'landmass') specifies any of the following regions of mask:
'Africa and Eurasia'
'North and South America'
'New Zealand North Island'
'New Zealand South Island'
land = landmask(...,quality) specifies quality from 0 to 100. This option is provided because for large data sets, the land mask function can take quite some time. For example, on my laptop, a calculating 180x360 land mask for all continents takes about 65 seconds at 100% quality. Default quality is 95, which takes about 6 seconds for the same dataset on my laptop. The quality setting is only used when calculating the land mask using all of the world's continents. For single land masses, 100% quality is assumed.
Chad Greene (2020). landmask (https://www.mathworks.com/matlabcentral/fileexchange/48661-landmask), MATLAB Central File Exchange. Retrieved .
What are the units for each coordinate? Should I use -15 or 345 for 15W?
Ha, indeed! Good catch!
In the examples in the documentation, I believe the long. for Topeka KS should be -95.69, not 95.69. (It is approx 95.69 West, not East).
The location (39.06,+95.69) is in western China, so
returns 1, but
landmask(39.06,95.69,'North and South America')
returns 0, and
landmask(39.06,95.69,'Africa and Eurasia')