rotate {clim.pact} | R Documentation |
The function uses the 3-dimensional space to find vectors describing the locations on a sphere that correspond to a given longitude and latitude. Two reference points are given, one for the new 'north pole': vec{r}_0 = [cos(phi_0)cos(theta_0),sin(phi_0),cos(phi_0)sin(theta_0)] and one for a point on the same meridian rx, but closer to the equator. The vector corresponing to each of the longitude-latitude point is given by: vec{r}_i = [cos(phi_i)cos(theta_i),sin(phi_i),cos(phi_i)sin(theta_i)].
The new spherical coordinates are computed as follows: new latitude
(phi
) is the angle between the the vectors r0
and r[i]. The new longitude (theta
) is the
angle between the the vectors r[i]-r0
and rx-r0. The angles are estimated by
taking the inner-product and the arc-cosine.
rotate(lons,lats,lon.0=NULL,lat.0=NULL, method = "Cayley-Klein", test = TRUE)
lons |
Longitude coordinates to be rotated. |
lats |
Latitude coordinates to be rotated. |
lon.0 |
Longitude coordinate of point corresponding to new 'north'pole. |
lat.0 |
Latitude coordinate of point corresponding to new 'north'pole. |
method |
|
test |
list containing phi
and theta
, the new spherical coordinates.
R.E. Benestad