Equidistant cylindrical grib decoder and grid coordinate transformations. More...

Data Types
type	ip_equid_cylind_grid

Functions/Subroutines
subroutine	equid_cylind_grid_area (RLAT, AREA)
	Computes the grid box area for a equidistant cylindrical grid. More...

subroutine	equid_cylind_map_jacob (XLON, XLAT, YLON, YLAT)
	Computes the map jacobians for a equidistant cylindrical grid. More...

subroutine	equid_cylind_vect_rot (CROT, SROT)
	Computes the vector rotation sines and cosines for a equidistant cylindrical grid. More...

subroutine	gdswzd_equid_cylind (self, IOPT, NPTS, FILL, XPTS, YPTS, RLON, RLAT, NRET, CROT, SROT, XLON, XLAT, YLON, YLAT, AREA)
	Calculates Earth coordinates (iopt = 1) or grid coorindates (iopt = -1) for equidistant cylindrical grids. More...

subroutine	init_grib1 (self, g1_desc)
	Initializes an equidistant cylindrical grid given a grib1_descriptor object. More...

subroutine	init_grib2 (self, g2_desc)
	Initializes an equidistant cylindrical grid given a grib2_descriptor object. More...

Variables
real	dlat
	Grid resolution in degrees n/s direction. More...

real	dlon
	Grid resolution in degrees e/w direction. More...

real	rerth
	Radius of the Earth. More...

Detailed Description

Equidistant cylindrical grib decoder and grid coordinate transformations.

Octet numbers refer to [GRIB2 - GRID DEFINITION TEMPLATE 3.0 Latitude/Longitude or equidistant cylindrical, or Plate Carree](https://www.nco.ncep.noaa.gov/pmb/docs/grib2/grib2_doc/grib2_temp3-0.shtml).

Author: George Gayno, Mark Iredell, Kyle Gerheiser

Date: July 2021

Function/Subroutine Documentation

◆ equid_cylind_grid_area()

subroutine ip_equid_cylind_grid_mod::equid_cylind_grid_area	(	real, intent(in)	RLAT,
		real, intent(out)	AREA
	)

private

Computes the grid box area for a equidistant cylindrical grid.

Parameters

[in]	rlat	Latitude of grid point in degrees.
[out]	area	Area weights in m^2.

Author: Mark Iredell, George Gayno

Date: July 2021

Definition at line 363 of file ip_equid_cylind_grid_mod.F90.

References dlat, dlon, and rerth.

Referenced by gdswzd_equid_cylind().

◆ equid_cylind_map_jacob()

subroutine ip_equid_cylind_grid_mod::equid_cylind_map_jacob	(	real, intent(out)	XLON,
		real, intent(out)	XLAT,
		real, intent(out)	YLON,
		real, intent(out)	YLAT
	)

private

Computes the map jacobians for a equidistant cylindrical grid.

Parameters

[out]	xlon	dx/dlon in 1/degrees.
[out]	xlat	dx/dlat in 1/degrees.
[out]	ylon	dy/dlon in 1/degrees.
[out]	ylat	dy/dlat in 1/degrees.

Author: George Gayno

Date: July 2021

Definition at line 346 of file ip_equid_cylind_grid_mod.F90.

References dlat, and dlon.

Referenced by gdswzd_equid_cylind().

◆ equid_cylind_vect_rot()

subroutine ip_equid_cylind_grid_mod::equid_cylind_vect_rot	(	real, intent(out)	CROT,
		real, intent(out)	SROT
	)

private

Computes the vector rotation sines and cosines for a equidistant cylindrical grid.

Parameters

[out]	crot	Clockwise vector rotation cosines.
[out]	srot	Clockwise vector rotation sines.

Note

ugrid=crot*uearth-srot*vearth;
vgrid=srot*uearth+crot*vearth

Author: George Gayno

Date: July 2021

Definition at line 327 of file ip_equid_cylind_grid_mod.F90.

Referenced by gdswzd_equid_cylind().

◆ gdswzd_equid_cylind()

subroutine ip_equid_cylind_grid_mod::gdswzd_equid_cylind	(	class(ip_equid_cylind_grid), intent(in)	self,
		integer, intent(in)	IOPT,
		integer, intent(in)	NPTS,
		real, intent(in)	FILL,
		real, dimension(npts), intent(inout)	XPTS,
		real, dimension(npts), intent(inout)	YPTS,
		real, dimension(npts), intent(inout)	RLON,
		real, dimension(npts), intent(inout)	RLAT,
		integer, intent(out)	NRET,
		real, dimension(npts), intent(out), optional	CROT,
		real, dimension(npts), intent(out), optional	SROT,
		real, dimension(npts), intent(out), optional	XLON,
		real, dimension(npts), intent(out), optional	XLAT,
		real, dimension(npts), intent(out), optional	YLON,
		real, dimension(npts), intent(out), optional	YLAT,
		real, dimension(npts), intent(out), optional	AREA
	)

private

Calculates Earth coordinates (iopt = 1) or grid coorindates (iopt = -1) for equidistant cylindrical grids.

If the selected coordinates are more than one gridpoint beyond the the edges of the grid domain, then the relevant output elements are set to fill values.

The actual number of valid points computed is returned too. Optionally, the vector rotations, the map jacobians and the grid box areas may be returned as well.

To compute the vector rotations, the optional arguments 'srot' and 'crot' must be present.

To compute the map jacobians, the optional arguments 'xlon', 'xlat', 'ylon', 'ylat' must be present.

To compute the grid box areas, the optional argument 'area' must be present.

Parameters

[in]	self	The grid object gdswzd was called on.
[in]	iopt	option flag +1 to compute earth coords of selected grid coords. -1 o compute grid coords of selected earth coords.
[in]	npts	Maximum number of coordinates.
[in]	fill	Fill value to set invalid output data. Must be impossible value; suggested value: -9999.
[in,out]	xpts	Grid x point coordinates if iopt>0.
[in,out]	ypts	Grid y point coordinates if iopt>0.
[in,out]	rlon	Earth longitudes in degrees e if iopt<0 (Acceptable range: -360. to 360.)
[in,out]	rlat	Earth latitudes in degrees n if iopt<0 (Acceptable range: -90. to 90.)
[out]	nret	Number of valid points computed.
[out]	crot	Optional clockwise vector rotation cosines.
[out]	srot	Optional clockwise vector rotation sines.
[out]	xlon	Optional dx/dlon in 1/degrees.
[out]	xlat	Optional dx/dlat in 1/degrees.
[out]	ylon	Optional dy/dlon in 1/degrees.
[out]	ylat	Optional dy/dlat in 1/degrees.
[out]	area	Optional area weights in m**2.