Gaussian grid coordinate transformations. More...

Data Types
type	ip_gaussian_grid

Functions/Subroutines
subroutine	gaussian_grid_area (YPTS, AREA)
	Computes the grid box area for a gaussian cylindrical grid. More...

subroutine	gaussian_map_jacob (YPTS, XLON, XLAT, YLON, YLAT)
	Computes the map jacobians for a gaussian cylindrical grid. More...

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

subroutine	gdswzd_gaussian (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 Gaussian grids. More...

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

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

Variables
real, dimension(:), allocatable	blat
	Gaussian latitude for each parallel. More...

real	dlon
	"i"-direction increment. More...

integer	j1
	'j' index of first grid point within the global array of latitudes. More...

integer	jh
	Scan mode flag in 'j' direction. More...

real	rerth
	Radius of the earth. More...

real, dimension(:), allocatable	ylat_row
	dy/dlat for each row in 1/degrees. More...

Detailed Description

Gaussian grid coordinate transformations.

Octet numbers refer to [GRIB2 - GRID DEFINITION TEMPLATE 3.40 Gaussian Latitude/Longitude](https://www.nco.ncep.noaa.gov/pmb/docs/grib2/grib2_doc/grib2_temp3-40.shtml).

Author: George Gayno, Mark Iredell, Kyle Gerheiser

Date: July 2021

Function/Subroutine Documentation

◆ gaussian_grid_area()

subroutine ip_gaussian_grid_mod::gaussian_grid_area	(	real, intent(in)	YPTS,
		real, intent(out)	AREA
	)

private

Computes the grid box area for a gaussian cylindrical grid.

Parameters

[in]	ypts	y-index of grid point.
[out]	area	Area weights in m^2

Author: Mark Iredell, George Gayno

Date: July 2021

Definition at line 416 of file ip_gaussian_grid_mod.F90.

References blat, dlon, j1, jh, and rerth.

Referenced by gdswzd_gaussian().

◆ gaussian_map_jacob()

subroutine ip_gaussian_grid_mod::gaussian_map_jacob	(	real, intent(in)	YPTS,
		real, intent(out)	XLON,
		real, intent(out)	XLAT,
		real, intent(out)	YLON,
		real, intent(out)	YLAT
	)

private

Computes the map jacobians for a gaussian cylindrical grid.

Parameters

[in]	ypts	y-index of grid point.
[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 396 of file ip_gaussian_grid_mod.F90.

References dlon, and ylat_row.

Referenced by gdswzd_gaussian().

◆ gaussian_vect_rot()

subroutine ip_gaussian_grid_mod::gaussian_vect_rot	(	real, intent(out)	CROT,
		real, intent(out)	SROT
	)

private

Computes the vector rotation sines and cosines for a gaussian 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 376 of file ip_gaussian_grid_mod.F90.

Referenced by gdswzd_gaussian().

◆ gdswzd_gaussian()

subroutine ip_gaussian_grid_mod::gdswzd_gaussian	(	class(ip_gaussian_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 Gaussian 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.

Author: Mark Iredell, George Gayno, Kyle Gerheiser

Date: July 2021

Definition at line 194 of file ip_gaussian_grid_mod.F90.

References blat, dlon, gaussian_grid_area(), gaussian_map_jacob(), gaussian_vect_rot(), j1, jh, rerth, splat(), and ylat_row.

◆ init_grib1()

subroutine ip_gaussian_grid_mod::init_grib1	(	class(ip_gaussian_grid), intent(inout)	self,
		type(grib1_descriptor), intent(in)	g1_desc
	)

private

Initializes a gaussian grid given a grib1_descriptor object.

Parameters

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

Author: Kyle Gerheiser

Date: July 2021

Definition at line 59 of file ip_gaussian_grid_mod.F90.

◆ init_grib2()

subroutine ip_gaussian_grid_mod::init_grib2	(	class(ip_gaussian_grid), intent(inout)	self,
		type(grib2_descriptor), intent(in)	g2_desc
	)

private

Initializes a gaussian grid given a grib2_descriptor object.

Parameters

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

Author: Kyle Gerheiser

Date: July 2021

Definition at line 108 of file ip_gaussian_grid_mod.F90.

Variable Documentation

◆ blat

real, dimension(:), allocatable ip_gaussian_grid_mod::blat

private

Gaussian latitude for each parallel.

Definition at line 45 of file ip_gaussian_grid_mod.F90.

Referenced by gaussian_grid_area(), and gdswzd_gaussian().

◆ dlon

real ip_gaussian_grid_mod::dlon

private

"i"-direction increment.

GRIB2 Section 3, octets 64-67.

Definition at line 46 of file ip_gaussian_grid_mod.F90.

Referenced by gaussian_grid_area(), gaussian_map_jacob(), and gdswzd_gaussian().

◆ j1

integer ip_gaussian_grid_mod::j1

private

'j' index of first grid point within the global array of latitudes.

Definition at line 43 of file ip_gaussian_grid_mod.F90.

Referenced by gaussian_grid_area(), and gdswzd_gaussian().

◆ jh

integer ip_gaussian_grid_mod::jh

private

Scan mode flag in 'j' direction.

When '1' points scan from N to S. When "-1" points scan from S to N.

Definition at line 44 of file ip_gaussian_grid_mod.F90.

Referenced by gaussian_grid_area(), and gdswzd_gaussian().

◆ rerth

real ip_gaussian_grid_mod::rerth

private

Radius of the earth.

GRIB2 Section 3, octets 15-30.

Definition at line 47 of file ip_gaussian_grid_mod.F90.

Referenced by gaussian_grid_area(), and gdswzd_gaussian().

◆ ylat_row

real, dimension(:), allocatable ip_gaussian_grid_mod::ylat_row

private

dy/dlat for each row in 1/degrees.

Definition at line 48 of file ip_gaussian_grid_mod.F90.

Referenced by gaussian_map_jacob(), and gdswzd_gaussian().

Data Types

Functions/Subroutines

Variables

Detailed Description

Function/Subroutine Documentation

◆ gaussian_grid_area()

◆ gaussian_map_jacob()

◆ gaussian_vect_rot()

◆ gdswzd_gaussian()

◆ init_grib1()

◆ init_grib2()

Variable Documentation

◆ blat

◆ dlon

◆ j1

◆ jh

◆ rerth

◆ ylat_row