grid_tools
1.5.0
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Private Member Functions | |
subroutine | hgrid_ak_rc (lx, ly, nx, ny, A, K, plat, plon, pazi, delx, dely, xc, xcd, garea, ff) |
Use a and k as the parameters of an Extended Schmidt-transformed Gnomonic (ESG) mapping centered at (plat,plon) and twisted about this center by an azimuth angle of pazi counterclockwise (these angles in radians). More... | |
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private |
Use a and k as the parameters of an Extended Schmidt-transformed Gnomonic (ESG) mapping centered at (plat,plon) and twisted about this center by an azimuth angle of pazi counterclockwise (these angles in radians).
Assume the radius of the earth is unity, and using the central mapping point as the coordinate origin, set up the grid with central x-spacing delx and y-spacing dely. The grid index location of the left-lower corner of the domain is (lx,ly) (typically both NEGATIVE). The numbers of the grid spaces in x and y directions are nx and ny. (Note that, for a centered rectangular grid lx and ly are negative and, in magnitude, half the values of nx and ny respectively.) Return the unit cartesian vectors xc of the grid points and their jacobian matrices xcd wrt the map coordinates, and return a rectangular array, garea, of dimensions nx-1 by ny-1, that contains the areas of each of the grid cells
If all goes well, return a lowered failure flag, ff=.false. . But if, for some reason, it is not possible to complete this task, return the raised failure flag, ff=.TRUE. .
lx | center-relative x grid index for left edge of the domain |
ly | center-relative y grid index for lower edge of the domain |
nx | numbers of the grid spaces in x |
ny | numbers of the grid spaces in y |
a | parameters of the ESG mapping centered at (plat,plon) |
k | parameters of the ESG mapping centered at (plat,plon) |
plat | latitude of the projection center of the mapping (radians) |
plon | longitude of the projection center of the mapping (radians) |
pazi | azimuth of orientation of mapping at its center |
delx | central x-spacing of the grid (in radians) |
dely | central y-spacing of the grid (in radians) |
xc | Earth-centered unit cartesian 3-vectors at each grid point |
xcd | Jacobian matrices, d(xc)/d(xm), at each grid point |
garea | rectangular array of grid-cell areas (steradians) |
ff | failure flag |