I am posting an algorithm (more of a procedure description) and I request a review of the correctness of the algorithm.
Goal - To bring in scalar field values such as temperature, geopotential height, surface pressure, specific humidity found in a NOAA reanalysis file(typically Gaussian grid) into a rotated lat lon grid.This algorithm does NOT apply to vector field values such as zonal and meridional velocities.
Given the following inputs-
- latitude of the rotated north pole
- longitude of the rotated north pole
- latitude of the geographical north pole
- longitude of the geographical north pole
Step 1 - Given the four input values use the following public routines available to transform coordinates in global Gaussian grid to rotated lat lon grid phi2phirot and rla2rlarot
Step 2 - Since these are scalar field values there are no transformation equations for Temperature, Surface Pressure, Geopotential height and Specific Humidity. They remain unchanged to a change of coordinate systems( Scalar Fields unchanged. However the positions of the scalar field values would now be different(change of origin).
I am aware that there is a similar question on GIS SE - Transforming from regular lat lon to rotated lat lon they use a different approach by transforming first to Cartesian and then transforming back into lat lon. The public routines that I cite do not require a transformation to Cartesian first.
Lauritzen, P. H., C. Jablonowski, M. A. Taylor, and R. D. Nair (2010), Rotated Versions of the Jablonowski Steady-State and Baroclinic Wave Test Cases: A Dynamical Core Intercomparison, J. Adv. Model. Earth Syst., 2, 15, doi:10.3894/JAMES.2010.2.15