pesg::bestesg_map Interface Reference

Private Member Functions
subroutine	bestesg_map (lam, marcx, marcy, a, k, garcx, garcy, q, ff)
	Get the best Extended Schmidt Gnomonic parameter, (a,k), for the given map-coordinate half-spans, marcx and marcy, as well as the corresponding geographical half-spans, garcx and garcy (in degrees) and the quality diagnostic, Q(lam) for this optimal parameter choice. More...

Detailed Description

Definition at line 43 of file pesg.f90.

Constructor & Destructor Documentation

bestesg_map()

subroutine pesg::bestesg_map::bestesg_map ( real(dp), intent(in)  lam, real(dp), intent(in)  marcx, real(dp), intent(in)  marcy, real(dp), intent(out)  a, real(dp), intent(out)  k, real(dp), intent(out)  garcx, real(dp), intent(out)  garcy, real(dp), intent(out)  q, logical, intent(out)  ff  )

private

Get the best Extended Schmidt Gnomonic parameter, (a,k), for the given map-coordinate half-spans, marcx and marcy, as well as the corresponding geographical half-spans, garcx and garcy (in degrees) and the quality diagnostic, Q(lam) for this optimal parameter choice.

If this process fails for any reason, the failure is alerted by a raised flag, FF, and the other output arguments must then be taken to be meaningless.

The diagnostic Q measures the variance over the domain of a local measure of grid distortion. A logarithmic measure of local grid deformation is give by L=log(J^t.J)/2, where J is the mapping Jacobian matrix, dX/dx, where X is the cartesian unit 3-vector representation of the image of the mapping of the map-coordinate 2-vector, x. The Frobenius squared-norm, Trace(L*L), of L is the basis for the simplest (lam=0) definition of the variance of L, but (Trace(L))**2 is another. Here, we weight both contributions, by lam and (1-lam) respectively, with 0 <= lam <1, to compute the variance Q(lam,a,k), and search for the (a,k) that minimizes this Q.

The domain averages are computed by double Gauss-Legendre quadrature (i.e., in both the x and y directions), but restricted to a mere quadrant of the domain (since bilateral symmetry pertains across both domain medians, yielding a domain mean L that is strictly diagonal.

Parameters

[in]	lam
[in]	marcx	map-coordinate half-spans
[in]	marcy	map-coordinate half-spans
[out]	a	Extended Schmidt Gnomonic parameter
[out]	k	Extended Schmidt Gnomonic parameter
[out]	garcx	geographical half-spans
[out]	garcy	geographical half-spans
[out]	q
[out]	ff	failure flag

Author

R. J. Purser

Definition at line 1073 of file pesg.f90.

---

The documentation for this interface was generated from the following file:

• /scratch1/NCEPDEV/da/George.Gayno/ufs_utils.git/UFS_UTILS/sorc/grid_tools.fd/regional_esg_grid.fd/pesg.f90