A land mask based on the GSHHS data set

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.

Usage

gshhsMask(res = 0.1, latmin = -90, latmax = 90)

landmask_init(res = 0.1, latmin = -90, latmax = 90)

Arguments

res

numeric: the spatial resolution of the mask, in degrees (either 0.1 or 0.05)

latmin

numeric: southernmost latitude extent of the land mask

latmax

numeric: northernmost latitude extent of the land mask

Value

function that returns a logical indicating whether the point is at sea (TRUE) or on land (FALSE)

References

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

See also

surrogateAR

Examples

mask  <- gshhsMask() ## initialize land mask function
mask(0, c(100, -65)) ## test point lon,lat
#> [1] TRUE