geocat.comp.gradient._rad_lat_wgs84

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geocat.comp.gradient._rad_lat_wgs84#

geocat.comp.gradient._rad_lat_wgs84(lat)#

The radius calculation for the wgs84 ellipsoid at a latitude uses a taylor series from.

\[radius = \sqrt{a^2 \cdot cos(lat)^2+b^2 \cdot sin(lat)^2}\]

This returns the radius of the ellipsoid for a given latitude This is accurate to within floating point error.

Note

This doesn’t need to be a taylor series, though the taylor series is faster and a needed step for the _arc_lat_wgs84 function to avoid the elliptic integral

Parameters:

lat (numpy.ndarray, xarray.DataArray) – 2-dimensional dataset, of orthographic latitude coordinates

Returns:

gradients (list of numpy.ndarray, list of xarray.DataArray) – latitudinal radii calculated using th WGS84 geoid.

See also

Related NCL Functions: grad_latlon_cfd, gradsf, gradsg