Generate a land mask function based on the Global Self-consistent, Hierarchical, High-resolution Geography Database.
The mask is provided at two (approximate) spatial resolutions: 0.1 degree and 0.05 degrees. The latter requires significantly more memory.
The mask is constant and the tm
argument to the mask is ignored.
gshhsMask(res = 0.1) landmask_init(res = 0.1)
res | numeric: the spatial resolution of the mask, in degrees (either 0.1 or 0.05) |
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function that returns a logical indicating whether the point is at sea (TRUE) or on land (FALSE)
Wessel P, Smith WHF (1996) A Global Self-consistent, Hierarchical, High-resolution Shoreline Database. J. Geophys. Res. 101: 8741-8743. https://www.ngdc.noaa.gov/mgg/shorelines/gshhs.html
#> [1] TRUE