GDS wizard for polar stereographic azimuthal. More...

Data Types
type	ip_polar_stereo_grid

Functions/Subroutines
subroutine	gdswzd_polar_stereo (self, IOPT, NPTS, FILL, XPTS, YPTS, RLON, RLAT, NRET, CROT, SROT, XLON, XLAT, YLON, YLAT, AREA)
	GDS wizard for polar stereographic azimuthal. More...

subroutine	init_grib1 (self, g1_desc)
	Initializes a polar stereographic grid given a grib1_descriptor object. More...

subroutine	init_grib2 (self, g2_desc)
	Initializes a polar stereographic grid given a grib2_descriptor object. More...

subroutine	polar_stereo_grid_area (RLAT, DR2, AREA)
	Grid box area for polar stereographic grids. More...

subroutine	polar_stereo_map_jacob (RLON, RLAT, DR2, XLON, XLAT, YLON, YLAT)
	Map jacobians for polar stereographic grids. More...

subroutine	polar_stereo_vect_rot (RLON, CROT, SROT)
	Vector rotation fields for polar stereographic grids. More...

Variables
real	de2
	Square of DE. More...

real	dxs
	Local copy of dxs. More...

real	dys
	Local copy of dys. More...

real	e2
	Eccentricity squared. More...

real	h
	Local copy of h. More...

integer	irot
	Local copy of irot. More...

real	orient
	Local copy of orient. More...

real	rerth
	Radius of the Earth. More...

Detailed Description

GDS wizard for polar stereographic azimuthal.

Octet numbers refer to [GRIB2 - GRID DEFINITION TEMPLATE 3.20 Polar stereographic projection](https://www.nco.ncep.noaa.gov/pmb/docs/grib2/grib2_doc/grib2_temp3-20.shtml).

Author: Iredell

Date: 96-04-10

Function/Subroutine Documentation

◆ gdswzd_polar_stereo()

subroutine ip_polar_stereo_grid_mod::gdswzd_polar_stereo	(	class(ip_polar_stereo_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

GDS wizard for polar stereographic azimuthal.

This subprogram decodes the grib 2 grid definition template (passed in integer form as decoded by the ncep g2 library) and returns one of the following:

(iopt=+1) earth coordinates of selected grid coordinates
(iopt=-1) grid coordinates of selected earth coordinates

Works for polar stereographic azimuthal projections.

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, map jacobians, and grid box areas may be returned as well. Routine works for both spherical and elliptical earths with the exception of the map jacobians and grid box areas, which are only computed for spherical earths.

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.

Program History Log

Date	Programmer	Comments
96-04-10	iredell	Initial
97-10-20	iredell	include map options
09-05-13	gayno	ensure area always positive
2015-01-21	gayno	merger of gdswiz05 and gdswzd05. make crot,sort,xlon,xlat,ylon,ylat and area optional arguments. make part of a module. move vector rotation, map jacobian and grid box area computations to separate subroutines. include option for elliptical earths.
2015-07-13	gayno	convert to grib 2. replace grib 1 kgds array with grib 2 grid definition template array. rename routine.
2018-07-20	wesley	add threading.

Parameters

[in]	self	grid
[in]	iopt	option flag 1 to compute earth coords of selected grid coords -1 to 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	(npts) grid x point coordinates if iopt>0
[in,out]	ypts	(npts) grid y point coordinates if iopt>0
[in,out]	rlon	(npts) earth longitudes in degrees e if iopt<0 (acceptable range: -360. to 360.)
[in,out]	rlat	(npts) earth latitudes in degrees n if iopt<0 (acceptable range: -90. to 90.)
[out]	nret	number of valid points computed
[out]	crot	optional (npts) clockwise vector rotation cosines
[out]	srot	optional (npts) clockwise vector rotation sines (ugrid=crotuearth-srotvearth; vgrid=srotuearth+crotvearth)
[out]	xlon	optional (npts) dx/dlon in 1/degrees
[out]	xlat	optional (npts) dx/dlat in 1/degrees
[out]	ylon	optional (npts) dy/dlon in 1/degrees
[out]	ylat	optional (npts) dy/dlat in 1/degrees
[out]	area	optional (npts) area weights in m**2 (proportional to the square of the map factor)

Author: Iredell

Date: 96-04-10

Definition at line 239 of file ip_polar_stereo_grid_mod.F90.

References de2, dxs, dys, e2, h, irot, orient, polar_stereo_grid_area(), polar_stereo_map_jacob(), polar_stereo_vect_rot(), and rerth.

◆ init_grib1()

subroutine ip_polar_stereo_grid_mod::init_grib1	(	class(ip_polar_stereo_grid), intent(inout)	self,
		type(grib1_descriptor), intent(in)	g1_desc
	)

private

Initializes a polar stereographic grid given a grib1_descriptor object.

Parameters

[in,out]	self	The grid to initialize
[in]	g1_desc	A grib1_descriptor

Author: Iredell

Date: 96-04-10

Definition at line 63 of file ip_polar_stereo_grid_mod.F90.

References ip_constants_mod::dpr, ip_constants_mod::e2_wgs84, and ip_constants_mod::rerth_wgs84.

◆ init_grib2()

subroutine ip_polar_stereo_grid_mod::init_grib2	(	class(ip_polar_stereo_grid), intent(inout)	self,
		type(grib2_descriptor), intent(in)	g2_desc
	)

private

Initializes a polar stereographic grid given a grib2_descriptor object.

Parameters

[in,out]	self	The grid to initialize
[in]	g2_desc	A grib2_descriptor

Author: Iredell

Date: 96-04-10

Definition at line 128 of file ip_polar_stereo_grid_mod.F90.

◆ polar_stereo_grid_area()

subroutine ip_polar_stereo_grid_mod::polar_stereo_grid_area	(	real, intent(in)	RLAT,
		real, intent(in)	DR2,
		real, intent(out)	AREA
	)

private

Grid box area for polar stereographic grids.

This subprogram computes the grid box area for a polar stereographic azimuthal grid (spherical earth).

Program History Log

Date	Programmer	Comments
2015-01-21	gayno	initial version
2015-09-17	gayno	rename as "polar_stereo_grid_area".
2018-07-20	wesley	pass in dr2 for threading.

Parameters

[in]	rlat	latitude of grid point in degrees (real)
[in]	dr2	squared distance from pole (real)
[out]	area	area weights in m**2 (real)

Author: Gayno

Date: 2015-01-21

Definition at line 563 of file ip_polar_stereo_grid_mod.F90.

References de2, dxs, dys, and rerth.

Referenced by gdswzd_polar_stereo().

◆ polar_stereo_map_jacob()

subroutine ip_polar_stereo_grid_mod::polar_stereo_map_jacob	(	real, intent(in)	RLON,
		real, intent(in)	RLAT,
		real, intent(in)	DR2,
		real, intent(out)	XLON,
		real, intent(out)	XLAT,
		real, intent(out)	YLON,
		real, intent(out)	YLAT
	)

private

Map jacobians for polar stereographic grids.

This subprogram computes the map jacobians for a polar stereographic azimuthal grid (spherical earth).

Program History Log

Date	Programmer	Comments
2015-01-21	gayno	initial version
2015-09-17	gayno	rename as "polar_stereo_map_jacob"
2018-07-20	wesley	pass in dr2 for threading.

Parameters

[in]	rlon	longitude in degrees (real)
[in]	rlat	latitude in degrees (real)
[in]	dr2	squared distance from pole (real)
[out]	xlon	dx/dlon in 1/degrees (real)
[out]	xlat	dx/dlat in 1/degrees (real)
[out]	ylon	dy/dlon in 1/degrees (real)
[out]	ylat	dy/dlat in 1/degrees (real)

Author: Gayno

Date: 2015-01-21

Definition at line 520 of file ip_polar_stereo_grid_mod.F90.

References de2, dxs, dys, h, and orient.

Referenced by gdswzd_polar_stereo().

◆ polar_stereo_vect_rot()

subroutine ip_polar_stereo_grid_mod::polar_stereo_vect_rot	(	real, intent(in)	RLON,
		real, intent(out)	CROT,
		real, intent(out)	SROT
	)

private

Vector rotation fields for polar stereographic grids.

This subprogram computes the vector rotation sines and cosines for a polar stereographic azimuthal grid.

Program History Log

Date	Programmer	Comments
2015-01-21	gayno	initial version
2015-09-17	gayno	rename as "polar_stereo_vect_rot"

Parameters

[in]	rlon	grid point longitude in degrees (real)
[in]	crot	clockwise vector rotation cosines (real)
[in]	srot	clockwise vector rotation sines (real) (ugrid=crotuearth-srotvearth; vgrid=srotuearth+crotvearth)