geocat.comp.gradient._arc_lat_wgs84#
- geocat.comp.gradient._arc_lat_wgs84(lat)#
The arc length calculation for the wgs84 ellipsoid at a latitude uses a taylor series to obtain the value of the elliptic integral.
\[arclat = \int_{0}^{lat}\sqrt{a^2 \cdot cos(lat)^2+b^2 \cdot sin(lat)^2}\ dlat\]The integral of the radius taylor series gives an arc length taylor series This returns the distance from the equator to a given latitude This is accurate to within floating point error.
Note
This needs to be a taylor series to avoid the elliptic integral
- Parameters
lat (
numpy.ndarray
,xarray.DataArray
) – 2-dimensional dataset, of orthographic latitude coordinates- Returns
gradients (
list
ofnumpy.ndarray
,list
ofxarray.DataArray
) – latitudinal arc from equator calculated using th WGS84 geoid.
See also
Related NCL Functions: grad_latlon_cfd, gradsf, gradsg