Functions releated to calculation of propagation paths. More...

#include <cmath>
#include <stdexcept>
#include "agenda_class.h"
#include "array.h"
#include "arts_omp.h"
#include "auto_md.h"
#include "check_input.h"
#include "geodetic.h"
#include "math_funcs.h"
#include "messages.h"
#include "mystring.h"
#include "logic.h"
#include "poly_roots.h"
#include "ppath.h"
#include "refraction.h"
#include "rte.h"
#include "special_interp.h"

Functions
Numeric	geometrical_ppc (const Numeric &r, const Numeric &za)
	geometrical_ppc More...

Numeric	geompath_za_at_r (const Numeric &ppc, const Numeric &a_za, const Numeric &r)
	geompath_za_at_r More...

Numeric	geompath_r_at_za (const Numeric &ppc, const Numeric &za)
	geompath_r_at_za More...

Numeric	geompath_lat_at_za (const Numeric &za0, const Numeric &lat0, const Numeric &za)
	geompath_lat_at_za More...

Numeric	geompath_l_at_r (const Numeric &ppc, const Numeric &r)
	geompath_l_at_r More...

Numeric	geompath_r_at_l (const Numeric &ppc, const Numeric &l)
	geompath_r_at_l More...

Numeric	geompath_r_at_lat (const Numeric &ppc, const Numeric &lat0, const Numeric &za0, const Numeric &lat)
	geompath_r_at_lat More...

void	geompath_from_r1_to_r2 (Vector &r, Vector &lat, Vector &za, Numeric &lstep, const Numeric &ppc, const Numeric &r1, const Numeric &lat1, const Numeric &za1, const Numeric &r2, const bool &tanpoint, const Numeric &lmax)
	geompath_from_r1_to_r2 More...

void	cart2zaaa (Numeric &za, Numeric &aa, const Numeric &dx, const Numeric &dy, const Numeric &dz)
	cart2zaaa More...

void	zaaa2cart (Numeric &dx, Numeric &dy, Numeric &dz, const Numeric &za, const Numeric &aa)
	zaaa2cart More...

void	rotationmat3D (Matrix &R, ConstVectorView vrot, const Numeric &a)
	rotationmat3D More...

void	map_daa (Numeric &za, Numeric &aa, const Numeric &za0, const Numeric &aa0, const Numeric &aa_grid)

Numeric	refraction_ppc (const Numeric &r, const Numeric &za, const Numeric &refr_index_air)
	refraction_ppc More...

void	resolve_lon (Numeric &lon, const Numeric &lon5, const Numeric &lon6)
	resolve_lon More...

void	find_tanpoint (Index &it, const Ppath ppath)
	find_tanpoint More...

Numeric	rsurf_at_lat (const Numeric &lat1, const Numeric &lat3, const Numeric &r1, const Numeric &r3, const Numeric &lat)
	rsurf_at_lat More...

void	plevel_slope_2d (Numeric &c1, ConstVectorView lat_grid, ConstVectorView refellipsoid, ConstVectorView z_surf, const GridPos &gp, const Numeric &za)
	plevel_slope_2d More...

void	plevel_slope_2d (Numeric &c1, const Numeric &lat1, const Numeric &lat2, const Numeric &r1, const Numeric &r2)
	plevel_slope_2d More...

Numeric	plevel_angletilt (const Numeric &r, const Numeric &c1)
	plevel_angletilt More...

bool	is_los_downwards (const Numeric &za, const Numeric &tilt)
	is_los_downwards More...

void	r_crossing_2d (Numeric &lat, Numeric &l, const Numeric &r_hit, const Numeric &r_start, const Numeric &lat_start, const Numeric &za_start, const Numeric &ppc)
	r_crossing_2d More...

Numeric	rslope_crossing2d (const Numeric &rp, const Numeric &za, const Numeric &r0, Numeric c1)
	rslope_crossing2d More...

void	plevel_crossing_2d (Numeric &r, Numeric &lat, Numeric &l, const Numeric &r_start0, const Numeric &lat_start, const Numeric &za_start, const Numeric &ppc, const Numeric &lat1, const Numeric &lat3, const Numeric &r1, const Numeric &r3, const bool &above)
	plevel_crossing_2d More...

Numeric	rsurf_at_latlon (const Numeric &lat1, const Numeric &lat3, const Numeric &lon5, const Numeric &lon6, const Numeric &r15, const Numeric &r35, const Numeric &r36, const Numeric &r16, const Numeric &lat, const Numeric &lon)
	rsurf_at_latlon More...

void	plevel_slope_3d (Numeric &c1, Numeric &c2, const Numeric &lat1, const Numeric &lat3, const Numeric &lon5, const Numeric &lon6, const Numeric &r15, const Numeric &r35, const Numeric &r36, const Numeric &r16, const Numeric &lat, const Numeric &lon, const Numeric &aa)
	plevel_slope_3d More...

void	plevel_slope_3d (Numeric &c1, Numeric &c2, ConstVectorView lat_grid, ConstVectorView lon_grid, ConstVectorView refellipsoid, ConstMatrixView z_surf, const GridPos &gp_lat, const GridPos &gp_lon, const Numeric &aa)
	plevel_slope_3d More...

Numeric	rslope_crossing3d (const Numeric &rp, const Numeric &za, const Numeric &r0, Numeric c1, Numeric c2)
	rslope_crossing3d More...

void	r_crossing_3d (Numeric &lat, Numeric &lon, Numeric &l, const Numeric &r_hit, const Numeric &r_start, const Numeric &lat_start, const Numeric &lon_start, const Numeric &za_start, const Numeric &ppc, const Numeric &x, const Numeric &y, const Numeric &z, const Numeric &dx, const Numeric &dy, const Numeric &dz)
	r_crossing_3d More...

void	ppath_init_structure (Ppath &ppath, const Index &atmosphere_dim, const Index &np)
	ppath_init_structure More...

void	ppath_set_background (Ppath &ppath, const Index &case_nr)
	ppath_set_background More...

Index	ppath_what_background (const Ppath &ppath)
	ppath_what_background More...

void	ppath_copy (Ppath &ppath1, const Ppath &ppath2, const Index &ncopy)
	ppath_copy More...

void	ppath_append (Ppath &ppath1, const Ppath &ppath2)
	ppath_append More...

void	ppath_start_1d (Numeric &r_start, Numeric &lat_start, Numeric &za_start, Index &ip, const Ppath &ppath)
	ppath_start_1d More...

void	ppath_end_1d (Ppath &ppath, ConstVectorView r_v, ConstVectorView lat_v, ConstVectorView za_v, ConstVectorView lstep, ConstVectorView n_v, ConstVectorView ng_v, ConstVectorView z_field, ConstVectorView refellipsoid, const Index &ip, const Index &endface, const Numeric &ppc)
	ppath_end_1d More...

void	ppath_start_2d (Numeric &r_start, Numeric &lat_start, Numeric &za_start, Index &ip, Index &ilat, Numeric &lat1, Numeric &lat3, Numeric &r1a, Numeric &r3a, Numeric &r3b, Numeric &r1b, Numeric &rsurface1, Numeric &rsurface3, Ppath &ppath, ConstVectorView lat_grid, ConstMatrixView z_field, ConstVectorView refellipsoid, ConstVectorView z_surface)
	ppath_start_2d More...

void	ppath_end_2d (Ppath &ppath, ConstVectorView r_v, ConstVectorView lat_v, ConstVectorView za_v, ConstVectorView lstep, ConstVectorView n_v, ConstVectorView ng_v, ConstVectorView lat_grid, ConstMatrixView z_field, ConstVectorView refellipsoid, const Index &ip, const Index &ilat, const Index &endface, const Numeric &ppc)
	ppath_end_2d More...

void	ppath_start_3d (Numeric &r_start, Numeric &lat_start, Numeric &lon_start, Numeric &za_start, Numeric &aa_start, Index &ip, Index &ilat, Index &ilon, Numeric &lat1, Numeric &lat3, Numeric &lon5, Numeric &lon6, Numeric &r15a, Numeric &r35a, Numeric &r36a, Numeric &r16a, Numeric &r15b, Numeric &r35b, Numeric &r36b, Numeric &r16b, Numeric &rsurface15, Numeric &rsurface35, Numeric &rsurface36, Numeric &rsurface16, Ppath &ppath, ConstVectorView lat_grid, ConstVectorView lon_grid, ConstTensor3View z_field, ConstVectorView refellipsoid, ConstMatrixView z_surface)
	ppath_start_3d More...

void	ppath_end_3d (Ppath &ppath, ConstVectorView r_v, ConstVectorView lat_v, ConstVectorView lon_v, ConstVectorView za_v, ConstVectorView aa_v, ConstVectorView lstep, ConstVectorView n_v, ConstVectorView ng_v, ConstVectorView lat_grid, ConstVectorView lon_grid, ConstTensor3View z_field, ConstVectorView refellipsoid, const Index &ip, const Index &ilat, const Index &ilon, const Index &endface, const Numeric &ppc)
	ppath_end_3d More...

void	do_gridrange_1d (Vector &r_v, Vector &lat_v, Vector &za_v, Numeric &lstep, Index &endface, const Numeric &r_start0, const Numeric &lat_start, const Numeric &za_start, const Numeric &ppc, const Numeric &lmax, const Numeric &ra, const Numeric &rb, const Numeric &rsurface)
	do_gridrange_1d More...

void	ppath_step_geom_1d (Ppath &ppath, ConstVectorView z_field, ConstVectorView refellipsoid, const Numeric &z_surface, const Numeric &lmax)
	ppath_step_geom_1d More...

void	do_gridcell_2d_byltest (Vector &r_v, Vector &lat_v, Vector &za_v, Numeric &lstep, Index &endface, const Numeric &r_start0, const Numeric &lat_start0, const Numeric &za_start, const Numeric &l_start, const Index &icall, const Numeric &ppc, const Numeric &lmax, const Numeric &lat1, const Numeric &lat3, const Numeric &r1a, const Numeric &r3a, const Numeric &r3b, const Numeric &r1b, const Numeric &rsurface1, const Numeric &rsurface3)
	do_gridcell_2d_byltest More...

void	ppath_step_geom_2d (Ppath &ppath, ConstVectorView lat_grid, ConstMatrixView z_field, ConstVectorView refellipsoid, ConstVectorView z_surface, const Numeric &lmax)
	ppath_step_geom_2d More...

void	do_gridcell_3d_byltest (Vector &r_v, Vector &lat_v, Vector &lon_v, Vector &za_v, Vector &aa_v, Numeric &lstep, Index &endface, const Numeric &r_start0, const Numeric &lat_start0, const Numeric &lon_start0, const Numeric &za_start, const Numeric &aa_start, const Numeric &l_start, const Index &icall, const Numeric &ppc, const Numeric &lmax, const Numeric &lat1, const Numeric &lat3, const Numeric &lon5, const Numeric &lon6, const Numeric &r15a, const Numeric &r35a, const Numeric &r36a, const Numeric &r16a, const Numeric &r15b, const Numeric &r35b, const Numeric &r36b, const Numeric &r16b, const Numeric &rsurface15, const Numeric &rsurface35, const Numeric &rsurface36, const Numeric &rsurface16)
	do_gridcell_3d_byltest More...

void	ppath_step_geom_3d (Ppath &ppath, ConstVectorView lat_grid, ConstVectorView lon_grid, ConstTensor3View z_field, ConstVectorView refellipsoid, ConstMatrixView z_surface, const Numeric &lmax)
	ppath_step_geom_3d More...

void	raytrace_1d_linear_basic (Workspace &ws, Array< Numeric > &r_array, Array< Numeric > &lat_array, Array< Numeric > &za_array, Array< Numeric > &l_array, Array< Numeric > &n_array, Array< Numeric > &ng_array, Index &endface, ConstVectorView p_grid, ConstVectorView refellipsoid, ConstTensor3View z_field, ConstTensor3View t_field, ConstTensor4View vmr_field, ConstVectorView f_grid, const Numeric &lmax, const Agenda &refr_index_air_agenda, const Numeric &lraytrace, const Numeric &rsurface, const Numeric &r1, const Numeric &r3, Numeric r, Numeric lat, Numeric za)
	raytrace_1d_linear_basic More...

void	ppath_step_refr_1d (Workspace &ws, Ppath &ppath, ConstVectorView p_grid, ConstTensor3View z_field, ConstTensor3View t_field, ConstTensor4View vmr_field, ConstVectorView f_grid, ConstVectorView refellipsoid, const Numeric &z_surface, const Numeric &lmax, const Agenda &refr_index_air_agenda, const String &rtrace_method, const Numeric &lraytrace)
	ppath_step_refr_1d More...

void	raytrace_2d_linear_basic (Workspace &ws, Array< Numeric > &r_array, Array< Numeric > &lat_array, Array< Numeric > &za_array, Array< Numeric > &l_array, Array< Numeric > &n_array, Array< Numeric > &ng_array, Index &endface, ConstVectorView p_grid, ConstVectorView lat_grid, ConstVectorView refellipsoid, ConstTensor3View z_field, ConstTensor3View t_field, ConstTensor4View vmr_field, ConstVectorView f_grid, const Numeric &lmax, const Agenda &refr_index_air_agenda, const Numeric &lraytrace, const Numeric &lat1, const Numeric &lat3, const Numeric &rsurface1, const Numeric &rsurface3, const Numeric &r1a, const Numeric &r3a, const Numeric &r3b, const Numeric &r1b, Numeric r, Numeric lat, Numeric za)
	raytrace_2d_linear_basic More...

void	ppath_step_refr_2d (Workspace &ws, Ppath &ppath, ConstVectorView p_grid, ConstVectorView lat_grid, ConstTensor3View z_field, ConstTensor3View t_field, ConstTensor4View vmr_field, ConstVectorView f_grid, ConstVectorView refellipsoid, ConstVectorView z_surface, const Numeric &lmax, const Agenda &refr_index_air_agenda, const String &rtrace_method, const Numeric &lraytrace)
	ppath_step_refr_2d More...

void	raytrace_3d_linear_basic (Workspace &ws, Array< Numeric > &r_array, Array< Numeric > &lat_array, Array< Numeric > &lon_array, Array< Numeric > &za_array, Array< Numeric > &aa_array, Array< Numeric > &l_array, Array< Numeric > &n_array, Array< Numeric > &ng_array, Index &endface, ConstVectorView refellipsoid, ConstVectorView p_grid, ConstVectorView lat_grid, ConstVectorView lon_grid, ConstTensor3View z_field, ConstTensor3View t_field, ConstTensor4View vmr_field, ConstVectorView f_grid, const Numeric &lmax, const Agenda &refr_index_air_agenda, const Numeric &lraytrace, const Numeric &lat1, const Numeric &lat3, const Numeric &lon5, const Numeric &lon6, const Numeric &rsurface15, const Numeric &rsurface35, const Numeric &rsurface36, const Numeric &rsurface16, const Numeric &r15a, const Numeric &r35a, const Numeric &r36a, const Numeric &r16a, const Numeric &r15b, const Numeric &r35b, const Numeric &r36b, const Numeric &r16b, Numeric r, Numeric lat, Numeric lon, Numeric za, Numeric aa)
	raytrace_3d_linear_basic More...

void	ppath_step_refr_3d (Workspace &ws, Ppath &ppath, ConstVectorView p_grid, ConstVectorView lat_grid, ConstVectorView lon_grid, ConstTensor3View z_field, ConstTensor3View t_field, ConstTensor4View vmr_field, ConstVectorView f_grid, ConstVectorView refellipsoid, ConstMatrixView z_surface, const Numeric &lmax, const Agenda &refr_index_air_agenda, const String &rtrace_method, const Numeric &lraytrace)
	ppath_step_refr_3d More...

void	ppath_start_stepping (Ppath &ppath, const Index &atmosphere_dim, ConstVectorView p_grid, ConstVectorView lat_grid, ConstVectorView lon_grid, ConstTensor3View z_field, ConstVectorView refellipsoid, ConstMatrixView z_surface, const Index &cloudbox_on, const ArrayOfIndex &cloudbox_limits, const bool &ppath_inside_cloudbox_do, ConstVectorView rte_pos, ConstVectorView rte_los, const Verbosity &verbosity)
	ppath_start_stepping More...

void	ppath_calc (Workspace &ws, Ppath &ppath, const Agenda &ppath_step_agenda, const Index &atmosphere_dim, const Vector &p_grid, const Vector &lat_grid, const Vector &lon_grid, const Tensor3 &t_field, const Tensor3 &z_field, const Tensor4 &vmr_field, const Vector &f_grid, const Vector &refellipsoid, const Matrix &z_surface, const Index &cloudbox_on, const ArrayOfIndex &cloudbox_limits, const Vector &rte_pos, const Vector &rte_los, const Numeric &ppath_lraytrace, const bool &ppath_inside_cloudbox_do, const Verbosity &verbosity)
	ppath_calc More...

Variables
const Numeric	DEG2RAD

const Numeric	RAD2DEG

const Numeric	RTOL = 1e-3

const Numeric	LATLONTOL = 1e-8

const Numeric	LACC = 1e-5

const Numeric	R_NOT_FOUND = -1

const Numeric	L_NOT_FOUND = 99e99

const Numeric	LAT_NOT_FOUND = 99e99

const Numeric	LON_NOT_FOUND = 99e99

Detailed Description

Functions releated to calculation of propagation paths.

Author: Patrick Eriksson patri.nosp@m.ck.e.nosp@m.rikss.nosp@m.on@c.nosp@m.halme.nosp@m.rs.s.nosp@m.e

Date: 2002-05-02

Functions to determine propagation paths for different atmospheric dimensionalities, with and without refraction.

The term propagation path is here shortened to ppath.

Definition in file ppath.cc.

Function Documentation

◆ cart2zaaa()

void cart2zaaa	(	Numeric &	za,
		Numeric &	aa,
		const Numeric &	dx,
		const Numeric &	dy,
		const Numeric &	dz
	)

cart2zaaa

Converts a cartesian directional vector to zenith and azimuth

This function and the sister function cart2zaaa handles transformation of line-of-sights. This in contrast to the sph/poslos functions that handles positions, or combinations of positions and line-of-sight.

The cartesian coordinate system used for these two functions can be defined as z : za = 0 x : za=90, aa=0 y : za=90, aa=90

Parameters

za	Out: LOS zenith angle at observation position.
aa	Out: LOS azimuth angle at observation position.
dx	x-part of LOS unit vector.
dy	y-part of LOS unit vector.
dz	z-part of LOS unit vector.

Author: Patrick Eriksson

Date: 2009-10-02

Definition at line 443 of file ppath.cc.

References dx, and RAD2DEG.

Referenced by adjust_los(), map_daa(), and specular_losCalc().

◆ do_gridcell_2d_byltest()

void do_gridcell_2d_byltest	(	Vector &	r_v,
		Vector &	lat_v,
		Vector &	za_v,
		Numeric &	lstep,
		Index &	endface,
		const Numeric &	r_start0,
		const Numeric &	lat_start0,
		const Numeric &	za_start,
		const Numeric &	l_start,
		const Index &	icall,
		const Numeric &	ppc,
		const Numeric &	lmax,
		const Numeric &	lat1,
		const Numeric &	lat3,
		const Numeric &	r1a,
		const Numeric &	r3a,
		const Numeric &	r3b,
		const Numeric &	r1b,
		const Numeric &	rsurface1,
		const Numeric &	rsurface3
	)

do_gridcell_2d_byltest

Works as do_gridcell_3d_byltest, but downscaled to 2D

Author: Patrick Eriksson

Date: 2013-08-16

Definition at line 2837 of file ppath.cc.

References abs, ANGTOL, cart2pol(), cart2poslos(), dx, LACC, LATLONTOL, max, poslos2cart(), Vector::resize(), rsurf_at_lat(), and RTOL.

Referenced by ppath_step_geom_2d(), and raytrace_2d_linear_basic().

◆ do_gridcell_3d_byltest()

void do_gridcell_3d_byltest	(	Vector &	r_v,
		Vector &	lat_v,
		Vector &	lon_v,
		Vector &	za_v,
		Vector &	aa_v,
		Numeric &	lstep,
		Index &	endface,
		const Numeric &	r_start0,
		const Numeric &	lat_start0,
		const Numeric &	lon_start0,
		const Numeric &	za_start,
		const Numeric &	aa_start,
		const Numeric &	l_start,
		const Index &	icall,
		const Numeric &	ppc,
		const Numeric &	lmax,
		const Numeric &	lat1,
		const Numeric &	lat3,
		const Numeric &	lon5,
		const Numeric &	lon6,
		const Numeric &	r15a,
		const Numeric &	r35a,
		const Numeric &	r36a,
		const Numeric &	r16a,
		const Numeric &	r15b,
		const Numeric &	r35b,
		const Numeric &	r36b,
		const Numeric &	r16b,
		const Numeric &	rsurface15,
		const Numeric &	rsurface35,
		const Numeric &	rsurface36,
		const Numeric &	rsurface16
	)

do_gridcell_3d_byltest

See ATD for a description of the algorithm.

Author: Patrick Eriksson

Date: 2002-11-28

Definition at line 3191 of file ppath.cc.

References abs, ANGTOL, cart2poslos(), cart2sph(), dx, LACC, LATLONTOL, max, POLELAT, poslos2cart(), Vector::resize(), resolve_lon(), rsurf_at_latlon(), and RTOL.

Referenced by ppath_step_geom_3d(), and raytrace_3d_linear_basic().

◆ do_gridrange_1d()

void do_gridrange_1d	(	Vector &	r_v,
		Vector &	lat_v,
		Vector &	za_v,
		Numeric &	lstep,
		Index &	endface,
		const Numeric &	r_start0,
		const Numeric &	lat_start,
		const Numeric &	za_start,
		const Numeric &	ppc,
		const Numeric &	lmax,
		const Numeric &	ra,
		const Numeric &	rb,
		const Numeric &	rsurface
	)

do_gridrange_1d

Calculates the geometrical path through a 1D grid range.

This function works as do_gridcell_2d, but is valid for 1D cases.

The coding of variables and end face is as for do_gridcell_2d, with the exception that end faces 2 and 4 do not exist here.

Parameters

r_v	Out: Vector with radius of found path points.
lat_v	Out: Vector with latitude of found path points.
za_v	Out: Vector with LOS zenith angle at found path points.
lstep	Out: Vector with length along the path between points.
endface	Out: Number coding for exit face.
r_start0	Radius of start point.
lat_start	Latitude of start point.
za_start	LOS zenith angle at start point.
ppc	Propagation path constant.
lmax	Maximum allowed length along the path. -1 = no limit.
ra	Radius of lower pressure level.
rb	Radius of upper pressure level (rb > ra);
rsurface	Radius for the surface.

Author: Patrick Eriksson

Date: 2002-12-02

Definition at line 2699 of file ppath.cc.

References geompath_from_r1_to_r2(), and RTOL.

Referenced by ppath_step_geom_1d(), and raytrace_1d_linear_basic().

◆ find_tanpoint()

void find_tanpoint	(	Index &	it,
		const Ppath	ppath
	)

find_tanpoint

Identifies the tangent point of a propagation path

The tangent points is defined as the point with the lowest altitude.

The index of the tangent point is determined. If no tangent point is found, the index is set to -1.

Parameters

it	Out: Index of tangent point
ppath	Propagation path structure.

Author: Patrick Eriksson

Date: 2012-04-07

Definition at line 705 of file ppath.cc.

References Ppath::np, and Ppath::pos.

Referenced by defocusing_sat2sat(), TangentPointExtract(), and TangentPointPrint().

◆ geometrical_ppc()

Numeric geometrical_ppc	(	const Numeric &	r,
		const Numeric &	za
	)

geometrical_ppc

Calculates the propagation path constant for pure geometrical calculations.

Both positive and negative zenith angles are handled.

Returns: Path constant.

Parameters

r	Radius of the sensor position.
za	Zenith angle of the sensor line-of-sight.

Author: Patrick Eriksson

Date: 2002-05-17

Definition at line 118 of file ppath.cc.

References abs, and DEG2RAD.

Referenced by ppath_start_stepping(), ppath_step_geom_1d(), ppath_step_geom_2d(), ppath_step_geom_3d(), raytrace_1d_linear_basic(), raytrace_2d_linear_basic(), and raytrace_3d_linear_basic().

◆ geompath_from_r1_to_r2()

void geompath_from_r1_to_r2	(	Vector &	r,
		Vector &	lat,
		Vector &	za,
		Numeric &	lstep,
		const Numeric &	ppc,
		const Numeric &	r1,
		const Numeric &	lat1,
		const Numeric &	za1,
		const Numeric &	r2,
		const bool &	tanpoint,
		const Numeric &	lmax
	)

geompath_from_r1_to_r2

Determines radii, latitudes and zenith angles between two points of a propagation path.

Both start and end point are included in the returned vectors.

Parameters

r	Output: Radius of propagation path points.
lat	Output: Latitude of propagation path points.
za	Output: Zenith angle of propagation path points.
lstep	Output: Distance along the path between the points.
ppc	Propagation path constant.
r1	Radius for first point.
lat1	Latitude for first point.
za1	Zenith angle for first point.
r2	Radius for second point.
tanpoint	True if there is a tangent point (r-based) between r1 and r2. Otherwise false.
lmax	Length criterion for distance between path points. A negative value means no length criterion.

Author: Patrick Eriksson

Date: 2002-07-03

Definition at line 341 of file ppath.cc.

References abs, ANGTOL, geompath_l_at_r(), geompath_lat_at_za(), geompath_r_at_l(), geompath_za_at_r(), max, Vector::resize(), and sign().

Referenced by do_gridcell_2d(), and do_gridrange_1d().

◆ geompath_l_at_r()

Numeric geompath_l_at_r	(	const Numeric &	ppc,
		const Numeric &	r
	)

geompath_l_at_r

Calculates the length from the tangent point for the given radius.

The tangent point is either real or imaginary depending on the zenith angle of the sensor. See geometrical_tangent_radius.

Returns: Length along the path from the tangent point. Always >= 0.

Parameters

ppc	Propagation path constant.
r	Radius of the point of concern.

Author: Patrick Eriksson

Date: 2002-05-20

Definition at line 246 of file ppath.cc.

References RTOL.

Referenced by do_gridcell_3d(), geompath_from_r1_to_r2(), plevel_crossing_2d(), ppath_start_stepping(), r_crossing_2d(), raytrace_1d_linear_basic(), and raytrace_2d_linear_basic().

◆ geompath_lat_at_za()

Numeric geompath_lat_at_za	(	const Numeric &	za0,
		const Numeric &	lat0,
		const Numeric &	za
	)

geompath_lat_at_za

Calculates the latitude for a given zenith angle along a geometrical propagation path.

Positive and negative zenith angles are handled. A positive zenith angle means a movement towards higher latitudes.

Returns: The latitude of the second point.

Parameters

za0	The zenith angle of the starting point.
lat0	The latitude of the starting point.
za	The zenith angle of the second point.

Author: Patrick Eriksson

Date: 2002-05-17

Definition at line 218 of file ppath.cc.

References abs.

Referenced by geompath_from_r1_to_r2(), ppath_start_stepping(), r_crossing_2d(), raytrace_1d_linear_basic(), and raytrace_2d_linear_basic().

◆ geompath_r_at_l()

Numeric geompath_r_at_l	(	const Numeric &	ppc,
		const Numeric &	l
	)

geompath_r_at_l

Calculates the radius for a distance from the tangent point.

The tangent point is either real or imaginary depending on the zenith angle of the sensor. See geometrical_tangent_radius.

Returns: Radius.

Parameters

ppc	Propagation path constant.
l	Length from the tangent point (positive or negative).

Author: Patrick Eriksson

Date: 2002-05-20

Definition at line 275 of file ppath.cc.

Referenced by geompath_from_r1_to_r2(), raytrace_1d_linear_basic(), and raytrace_2d_linear_basic().

◆ geompath_r_at_lat()

Numeric geompath_r_at_lat	(	const Numeric &	ppc,
		const Numeric &	lat0,
		const Numeric &	za0,
		const Numeric &	lat
	)

geompath_r_at_lat

Calculates the radius for a given latitude.

Returns: Radius at the point of interest.

Parameters

ppc	Propagation path constant.
lat0	Latitude at some other point of the path.
za0	Zenith angle for the point with latitude lat0.
lat	Latitude of the point of interest.

Author: Patrick Eriksson

Date: 2002-06-05

Definition at line 299 of file ppath.cc.

References abs, and geompath_r_at_za().

Referenced by do_gridcell_2d().

◆ geompath_r_at_za()

Numeric geompath_r_at_za	(	const Numeric &	ppc,
		const Numeric &	za
	)

geompath_r_at_za

Calculates the zenith angle for a given radius along a geometrical propagation path.

Both positive and negative zenith angles are handled.

Returns: Radius at the point of interest.

Parameters

ppc	Propagation path constant.
za	Zenith angle at the point of interest.

Author: Patrick Eriksson

Date: 2002-06-05

Definition at line 190 of file ppath.cc.

References abs, and DEG2RAD.

Referenced by geompath_r_at_lat().

◆ geompath_za_at_r()

Numeric geompath_za_at_r	(	const Numeric &	ppc,
		const Numeric &	a_za,
		const Numeric &	r
	)

geompath_za_at_r

Calculates the zenith angle for a given radius along a geometrical propagation path.

For downlooking cases, the two points must be on the same side of the tangent point.

Both positive and negative zenith angles are handled.

Returns: Zenith angle at the point of interest.

Parameters

ppc	Propagation path constant.
a_za	A zenith angle along the path on the same side of the tangent point as the point of interest.
r	Radius of the point of interest.

Author: Patrick Eriksson

Date: 2002-05-17

Definition at line 147 of file ppath.cc.

References abs, RAD2DEG, and RTOL.

Referenced by do_gridcell_3d(), geompath_from_r1_to_r2(), ppath_start_stepping(), r_crossing_2d(), raytrace_1d_linear_basic(), raytrace_2d_linear_basic(), and VectorZtanToZa1D().

◆ is_los_downwards()

bool is_los_downwards	(	const Numeric &	za,
		const Numeric &	tilt
	)

is_los_downwards

Determines if a line-of-sight is downwards compared to the angular tilt of the surface or a pressure level.

For example, this function can be used to determine if the line-of-sight goes into the surface for a starting point exactly on the surface radius.

As the radius of the surface and pressure levels varies as a function of latitude, it is not clear if a zenith angle of 90 is above or below e.g. the surface.

Returns: Boolean that is true if LOS is downwards.

Parameters

za	Zenith angle of line-of-sight.
tilt	Angular tilt of the surface or the pressure level (as returned by plevel_angletilt)

Author: Patrick Eriksson

Date: 2002-06-03

Definition at line 875 of file ppath.cc.

References abs.

Referenced by ppath_start_2d(), ppath_start_3d(), and ppath_start_stepping().

◆ map_daa()

void map_daa	(	Numeric &	za,
		Numeric &	aa,
		const Numeric &	za0,
		const Numeric &	aa0,
		const Numeric &	aa_grid
	)

Maps MBLOCK_AA_GRID values to correct ZA and AA

Sensor LOS azimuth angles and mblock_aa_grid values can not be added in a straightforward way due to properties of the polar coordinate system used to define line-of-sights. This function performs a "mapping" ensuring that the pencil beam directions specified by mblock_za_grid and mblock_aa_grid form a rectangular grid (on the unit sphere) for any za.

za0 and aa0 match the angles of the ARTS WSV sensor_los. aa_grid shall hold values "close" to 0. The limit is here set to 5 degrees.

Parameters

za	Out: Zenith angle matching aa0+aa_grid
aa	Out: Azimuth angles matching aa0+aa_grid
za0	Zenith angle
aa0	Centre azimuth angle
aa_grid	MBLOCK_AA_GRID values

Author: Patrick Eriksson

Date: 2009-10-02

Definition at line 576 of file ppath.cc.

References abs, cart2zaaa(), mult(), rotationmat3D(), and zaaa2cart().

Referenced by iyb_calc_za_loop_body().

◆ plevel_angletilt()

Numeric plevel_angletilt	(	const Numeric &	r,
		const Numeric &	c1
	)

plevel_angletilt

Calculates the angular tilt of the surface or a pressure level.

Note that the tilt value is a local value. The tilt for a constant slope value, is different for different radii.

Returns: The angular tilt.

Parameters

r	The radius for the level at the point of interest.
c1	The radial slope, as returned by e.g. plevel_slope_2d.

Author: Patrick Eriksson

Date: 2002-06-03

Definition at line 844 of file ppath.cc.

References RAD2DEG.

Referenced by ppath_start_2d(), ppath_start_3d(), ppath_start_stepping(), and specular_losCalc().

◆ plevel_crossing_2d()

void plevel_crossing_2d	(	Numeric &	r,
		Numeric &	lat,
		Numeric &	l,
		const Numeric &	r_start0,
		const Numeric &	lat_start,
		const Numeric &	za_start,
		const Numeric &	ppc,
		const Numeric &	lat1,
		const Numeric &	lat3,
		const Numeric &	r1,
		const Numeric &	r3,
		const bool &	above
	)

plevel_crossing_2d

Handles the crossing with a geometric ppaths step and a atmospheric grid box level for 2D.

That is, we have a part of a pressure level or the planet's surface, extending between two latitudes (lat1 and lat3). The radius at each latitude is given (r1 and r3). The function first of determines if the ppath crosses the level/surface between the two latitudes. If yes, the radius and the latitude of the crossing point are calculated.

If the given path point is on the pressure level (rp=r0), the solution of zero length is rejected.

Parameters

r	Out: Radius at crossing.
lat	Out: Latitude at crossing.
l	Out: Length between start and crossing points.
r_start0	In: Radius of start point.
lat_start	In: Latitude of start point.
za_start	In: LOS zenith angle at start point.
ppc	In: Propagation path constant.
lat1	In: Latitude of lower end.
lat3	In: Latitude of upper end.
r1	In: Radius at lat1.
r3	In: Radius at lat3.
above	In: True if ppath start point is above level. In: Otherwise false.

Author: Patrick Eriksson

Date: 2012-02-19

Definition at line 1121 of file ppath.cc.

References abs, ANGTOL, geompath_l_at_r(), L_NOT_FOUND, LAT_NOT_FOUND, max, min, plevel_slope_2d(), r_crossing_2d(), R_NOT_FOUND, rslope_crossing2d(), and rsurf_at_lat().

Referenced by do_gridcell_2d().

◆ plevel_slope_2d() [1/2]

void plevel_slope_2d	(	Numeric &	c1,
		const Numeric &	lat1,
		const Numeric &	lat2,
		const Numeric &	r1,
		const Numeric &	r2
	)

plevel_slope_2d

Calculates the radial slope of the surface or a pressure level for 2D.

This function returns the same quantity as the function above, but takes the radius and latitude at two points of the pressure level, instead of vector input. That is, for this function the interesting latitude range is known when calling the function.

Parameters

c1	Out: The radial slope [m/degree]
lat1	A latitude.
lat2	Another latitude.
r1	Radius at lat1.
r2	Radius at lat2.

Author: Patrick Eriksson

Date: 2002-12-21

Definition at line 817 of file ppath.cc.

◆ plevel_slope_2d() [2/2]

void plevel_slope_2d	(	Numeric &	c1,
		ConstVectorView	lat_grid,
		ConstVectorView	refellipsoid,
		ConstVectorView	z_surf,
		const GridPos &	gp,
		const Numeric &	za
	)

plevel_slope_2d

Calculates the radial slope of the surface or a pressure level for 2D.

The radial slope is here the derivative of the radius with respect to the latitude. The unit is accordingly m/degree.

Note that the radius is defined to change linearly between grid points, and the slope is constant between to points of the latitude grid. The radius can inside the grid range be expressed as r = r0(lat0) + c1*(lat-lat0) .

Note also that the slope is always calculated with respect to increasing latitudes, independently of the zenith angle. The zenith angle is only used to determine which grid range that is of interest when the position is exactly on top of a grid point.

Parameters

c1	Out: The radial slope [m/degree]
lat_grid	The latitude grid.
refellipsoid	As the WSV with the same name.
z_surf	Geometrical altitude of the surface, or the pressure level of interest, for the latitide dimension
gp	Latitude grid position for the position of interest
za	LOS zenith angle.

Author: Patrick Eriksson

Date: 2002-06-03

Definition at line 782 of file ppath.cc.

References gridpos2gridrange(), and refell2r().

Referenced by plevel_crossing_2d(), ppath_start_2d(), ppath_start_stepping(), and specular_losCalc().

◆ plevel_slope_3d() [1/2]

void plevel_slope_3d	(	Numeric &	c1,
		Numeric &	c2,
		const Numeric &	lat1,
		const Numeric &	lat3,
		const Numeric &	lon5,
		const Numeric &	lon6,
		const Numeric &	r15,
		const Numeric &	r35,
		const Numeric &	r36,
		const Numeric &	r16,
		const Numeric &	lat,
		const Numeric &	lon,
		const Numeric &	aa
	)

plevel_slope_3d

Calculates the radial slope of the surface or a pressure level for 3D.

For 2D the radius can be expressed as r = r0 + c1*dalpha, where alpha is the latitude. The radius is here for 3D expressed as a second order polynomial: r = r0 + c1*dalpha + c2*dalpha^2, where alpha is the angular change (in degrees) along the great circle along the given azimuth angle.

Parameters

c1	Out: See above. Unit is m/degree.
c2	Out: See above. Unit is m/degree^2.
lat1	Lower latitude of grid cell.
lat3	Upper latitude of grid cell.
lon5	Lower longitude of grid cell.
lon6	Upper longitude of grid cell.
r15	Radius at crossing of lat1 and lon5.
r35	Radius at crossing of lat3 and lon5.
r36	Radius at crossing of lat3 and lon6.
r16	Radius at crossing of lat1 and lon6.
lat	Latitude for which slope shall be determined.
lon	Longitude for which slope shall be determined.
aa	Azimuth angle for which slope shall be determined.

Author: Patrick Eriksson

Date: 2002-12-30

Definition at line 1354 of file ppath.cc.

References latlon_at_aa(), resolve_lon(), and rsurf_at_latlon().

Referenced by plevel_crossing_3d(), plevel_slope_3d(), ppath_start_3d(), ppath_start_stepping(), and specular_losCalc().

◆ plevel_slope_3d() [2/2]

void plevel_slope_3d	(	Numeric &	c1,
		Numeric &	c2,
		ConstVectorView	lat_grid,
		ConstVectorView	lon_grid,
		ConstVectorView	refellipsoid,
		ConstMatrixView	z_surf,
		const GridPos &	gp_lat,
		const GridPos &	gp_lon,
		const Numeric &	aa
	)

plevel_slope_3d

Calculates the radial slope of the surface or a pressure level for 3D.

For 2D where the radius can be expressed as r = r0 + c1*dalpha, where alpha is the latitude. The radius is here for 3D expressed as a second order polynomial: r = r0 + c1*dalpha + c2*dalpha^2, where alpha is the angular change (in degrees) along the great circle along the given azimuth angle.

For a point exactly on a grid value it is not clear if it is the range below or above that is of interest. The azimuth angle is used to resolve such cases.

Parameters

c1	Out: See above. Unit is m/degree.
c2	Out: See above. Unit is m/degree^2.
lat_grid	The latitude grid.
lon_grid	The longitude grid.
refellipsoid	As the WSV with the same name.
z_surf	Geometrical altitude of the surface, or the pressure level of interest.
gp_lat	Latitude grid position for the position of interest.
gp_lon	Longitude grid position for the position of interest.
aa	Azimuth angle.

Author: Patrick Eriksson

Date: 2002-06-03

Definition at line 1435 of file ppath.cc.

References abs, gridpos2gridrange(), interp(), interpweights(), is_lon_cyclic(), ConstVectorView::nelem(), plevel_slope_3d(), POLELAT, and refell2r().

◆ ppath_append()

void ppath_append	(	Ppath &	ppath1,
		const Ppath &	ppath2
	)

ppath_append

Combines two Ppath structures.

The function appends a Ppath structure to another structure.

All the data of ppath1 is kept.

The first point in ppath2 is assumed to be the same as the last in ppath1. Only ppath2 fields start_pos, start_los, start_lstep, pos, los, r, lstep, nreal, ngroup, gp_XXX and background are considered.

Parameters

ppath1	Output: Ppath structure to be expanded.
ppath2	The Ppath structure to include in ppath.

Author: Patrick Eriksson

Date: 2002-07-03

Definition at line 1948 of file ppath.cc.

References Ppath::background, Ppath::dim, Ppath::gp_lat, Ppath::gp_lon, Ppath::gp_p, gridpos_copy(), Ppath::los, Ppath::lstep, Ppath::ngroup, Ppath::np, Ppath::nreal, Ppath::pos, ppath_copy(), ppath_init_structure(), ppath_what_background(), Ppath::r, Ppath::start_los, Ppath::start_lstep, and Ppath::start_pos.

◆ ppath_calc()

void ppath_calc	(	Workspace &	ws,
		Ppath &	ppath,
		const Agenda &	ppath_step_agenda,
		const Index &	atmosphere_dim,
		const Vector &	p_grid,
		const Vector &	lat_grid,
		const Vector &	lon_grid,
		const Tensor3 &	t_field,
		const Tensor3 &	z_field,
		const Tensor4 &	vmr_field,
		const Vector &	f_grid,
		const Vector &	refellipsoid,
		const Matrix &	z_surface,
		const Index &	cloudbox_on,
		const ArrayOfIndex &	cloudbox_limits,
		const Vector &	rte_pos,
		const Vector &	rte_los,
		const Numeric &	ppath_lraytrace,
		const bool &	ppath_inside_cloudbox_do,
		const Verbosity &	verbosity
	)

ppath_calc

This is the core for the WSM ppathStepByStep.

This function takes mainly the same input as ppathStepByStep (that is, those input arguments are the WSV with the same name).

Parameters

ws	Current Workspace
ppath	Output: A Ppath structure
ppath_step_agenda	As the WSM with the same name.
atmosphere_dim	The atmospheric dimensionality.
p_grid	The pressure grid.
lat_grid	The latitude grid.
lon_grid	The longitude grid.
t_field	As the WSM with the same name.
z_field	As the WSM with the same name.
vmr_field	As the WSM with the same name.
f_grid	As the WSM with the same name.
refellipsoid	As the WSM with the same name.
z_surface	Surface altitude.
cloudbox_on	Flag to activate the cloud box.
cloudbox_limits	Index limits of the cloud box.
rte_pos	The position of the sensor.
rte_los	The line-of-sight of the sensor.
ppath_lraytrace	As the WSM with the same name.
ppath_inside_cloudbox_do	As the WSM with the same name.

Author: Patrick Eriksson

Date: 2003-01-08

Definition at line 5344 of file ppath.cc.

References abs, Ppath::background, chk_rte_los(), chk_rte_pos(), Ppath::constant, Ppath::end_los, Ppath::end_lstep, Ppath::end_pos, fractional_gp(), Ppath::gp_lat, Ppath::gp_lon, Ppath::gp_p, gridpos(), is_gridpos_at_index_i(), joker, Ppath::los, Ppath::lstep, Array< base >::nelem(), ConstVectorView::nelem(), Ppath::ngroup, Ppath::np, Ppath::nreal, Ppath::pos, ppath_copy(), ppath_init_structure(), ppath_set_background(), ppath_start_stepping(), ppath_step_agendaExecute(), ppath_what_background(), Ppath::r, Ppath::start_los, Ppath::start_lstep, and Ppath::start_pos.

Referenced by defocusing_general_sub(), defocusing_sat2sat(), iwp_cloud_opt_pathCalc(), MCIPA(), ppathFromRtePos2(), and ppathStepByStep().

◆ ppath_copy()

void ppath_copy	(	Ppath &	ppath1,
		const Ppath &	ppath2,
		const Index &	ncopy
	)

ppath_copy

Copy the content in ppath2 to ppath1.

The ppath1 structure must be allocated before calling the function. The structure can be allocated to hold more points than found in ppath2. The data of ppath2 is placed in the first positions of ppath1.

Parameters

ppath1	Output: Ppath structure.
ppath2	The ppath structure to be copied.
ncopy	Number of points in ppath2 to copy. If set to negative, the number is set to ppath2.np.

Author: Patrick Eriksson

Date: 2002-07-03

Definition at line 1876 of file ppath.cc.

References Ppath::background, Ppath::constant, Ppath::dim, Ppath::end_los, Ppath::end_lstep, Ppath::end_pos, Ppath::gp_lat, Ppath::gp_lon, Ppath::gp_p, gridpos_copy(), joker, Ppath::los, Ppath::lstep, Ppath::ngroup, Ppath::np, Ppath::nreal, Ppath::pos, Ppath::r, Ppath::start_los, Ppath::start_lstep, and Ppath::start_pos.

Referenced by ppath_append(), ppath_calc(), and ppathFromRtePos2().

◆ ppath_end_1d()

void ppath_end_1d	(	Ppath &	ppath,
		ConstVectorView	r_v,
		ConstVectorView	lat_v,
		ConstVectorView	za_v,
		ConstVectorView	lstep,
		ConstVectorView	n_v,
		ConstVectorView	ng_v,
		ConstVectorView	z_field,
		ConstVectorView	refellipsoid,
		const Index &	ip,
		const Index &	endface,
		const Numeric &	ppc
	)

ppath_end_1d

Internal help function for 1D path calculations.

The function performs the end part of the calculations, that are common for geometrical and refraction calculations.

See the code for details.

Author: Patrick Eriksson

Date: 2002-11-27

Definition at line 2052 of file ppath.cc.

References Ppath::constant, Ppath::gp_p, gridpos_check_fd(), gridpos_force_end_fd(), Ppath::los, Ppath::lstep, Array< base >::nelem(), ConstVectorView::nelem(), Ppath::ngroup, Ppath::nreal, Ppath::pos, ppath_init_structure(), ppath_set_background(), and Ppath::r.

Referenced by ppath_step_geom_1d(), and ppath_step_refr_1d().

◆ ppath_end_2d()

void ppath_end_2d	(	Ppath &	ppath,
		ConstVectorView	r_v,
		ConstVectorView	lat_v,
		ConstVectorView	za_v,
		ConstVectorView	lstep,
		ConstVectorView	n_v,
		ConstVectorView	ng_v,
		ConstVectorView	lat_grid,
		ConstMatrixView	z_field,
		ConstVectorView	refellipsoid,
		const Index &	ip,
		const Index &	ilat,
		const Index &	endface,
		const Numeric &	ppc
	)

ppath_end_2d

Internal help function for 2D path calculations.

The function performs the end part of the calculations, that are common for geometrical and refraction calculations.

See the code for details.

Author: Patrick Eriksson

Date: 2002-11-29

Definition at line 2240 of file ppath.cc.

References Ppath::constant, Ppath::gp_lat, Ppath::gp_p, gridpos_check_fd(), gridpos_force_end_fd(), Ppath::los, Ppath::lstep, Array< base >::nelem(), ConstVectorView::nelem(), Ppath::ngroup, Ppath::nreal, ConstMatrixView::nrows(), Ppath::pos, ppath_init_structure(), ppath_set_background(), Ppath::r, refell2r(), and w().

Referenced by ppath_step_geom_2d(), and ppath_step_refr_2d().

◆ ppath_end_3d()

void ppath_end_3d	(	Ppath &	ppath,
		ConstVectorView	r_v,
		ConstVectorView	lat_v,
		ConstVectorView	lon_v,
		ConstVectorView	za_v,
		ConstVectorView	aa_v,
		ConstVectorView	lstep,
		ConstVectorView	n_v,
		ConstVectorView	ng_v,
		ConstVectorView	lat_grid,
		ConstVectorView	lon_grid,
		ConstTensor3View	z_field,
		ConstVectorView	refellipsoid,
		const Index &	ip,
		const Index &	ilat,
		const Index &	ilon,
		const Index &	endface,
		const Numeric &	ppc
	)

ppath_end_3d

Internal help function for 3D path calculations.

The function performs the end part of the calculations, that are common for geometrical and refraction calculations.

See the code for details.

Author: Patrick Eriksson

Date: 2002-12-30

Definition at line 2527 of file ppath.cc.

References abs, Ppath::constant, Ppath::gp_lat, Ppath::gp_lon, Ppath::gp_p, gridpos_check_fd(), gridpos_force_end_fd(), Ppath::los, Ppath::lstep, ConstVectorView::nelem(), Ppath::ngroup, Ppath::nreal, POLELAT, Ppath::pos, ppath_init_structure(), ppath_set_background(), Ppath::r, refell2r(), and rsurf_at_latlon().

Referenced by ppath_step_geom_3d(), and ppath_step_refr_3d().

◆ ppath_init_structure()

void ppath_init_structure	(	Ppath &	ppath,
		const Index &	atmosphere_dim,
		const Index &	np
	)

ppath_init_structure

Initiates a Ppath structure to hold the given number of points.

All fields releated with the surface, symmetry and tangent point are set to 0 or empty. The background field is set to background case 0. The constant field is set to -1. The refraction field is set to 0.

The length of the lstep field is set to np-1.

Parameters

ppath	Output: A Ppath structure.
atmosphere_dim	The atmospheric dimensionality.
np	Number of points of the path.

Author: Patrick Eriksson

Date: 2002-05-17

Definition at line 1726 of file ppath.cc.

References Ppath::constant, Ppath::dim, Ppath::end_los, Ppath::end_lstep, Ppath::end_pos, Ppath::gp_lat, Ppath::gp_lon, Ppath::gp_p, Ppath::los, Ppath::lstep, max, Ppath::ngroup, Ppath::np, Ppath::nreal, Ppath::pos, ppath_set_background(), Ppath::r, Vector::resize(), Matrix::resize(), Ppath::start_los, Ppath::start_lstep, and Ppath::start_pos.

Referenced by cloud_ppath_update1D(), cloud_ppath_update1D_noseq(), cloud_ppath_update3D(), ppath_append(), ppath_calc(), ppath_end_1d(), ppath_end_2d(), ppath_end_3d(), ppath_start_stepping(), and ppathFromRtePos2().

◆ ppath_set_background()

void ppath_set_background	(	Ppath &	ppath,
		const Index &	case_nr
	)

ppath_set_background

Sets the background field of a Ppath structure.

The different background cases have a number coding to simplify a possible change of the strings and checking of the what case that is valid.

The case numbers are:
0. Unvalid.

Space.
The surface.
The cloud box boundary.
The interior of the cloud box.

Parameters

ppath	Output: A Ppath structure.
case_nr	Case number (see above)

Author: Patrick Eriksson

Date: 2002-05-17

Definition at line 1790 of file ppath.cc.

References Ppath::background.

Referenced by ppath_calc(), ppath_end_1d(), ppath_end_2d(), ppath_end_3d(), ppath_init_structure(), ppath_start_stepping(), and ppathFromRtePos2().

◆ ppath_start_1d()

void ppath_start_1d	(	Numeric &	r_start,
		Numeric &	lat_start,
		Numeric &	za_start,
		Index &	ip,
		const Ppath &	ppath
	)

ppath_start_1d

Internal help function for 1D path calculations.

The function does the asserts and determined some variables that are common for geometrical and refraction calculations.

See the code for details.

Author: Patrick Eriksson

Date: 2002-11-13

Definition at line 2017 of file ppath.cc.

References Ppath::gp_p, gridpos2gridrange(), Ppath::los, Ppath::np, Ppath::pos, and Ppath::r.

Referenced by ppath_step_geom_1d(), and ppath_step_refr_1d().

◆ ppath_start_2d()

void ppath_start_2d	(	Numeric &	r_start,
		Numeric &	lat_start,
		Numeric &	za_start,
		Index &	ip,
		Index &	ilat,
		Numeric &	lat1,
		Numeric &	lat3,
		Numeric &	r1a,
		Numeric &	r3a,
		Numeric &	r3b,
		Numeric &	r1b,
		Numeric &	rsurface1,
		Numeric &	rsurface3,
		Ppath &	ppath,
		ConstVectorView	lat_grid,
		ConstMatrixView	z_field,
		ConstVectorView	refellipsoid,
		ConstVectorView	z_surface
	)

ppath_start_2d

Internal help function for 2D path calculations.

The function does the asserts and determined some variables that are common for geometrical and refraction calculations.

See the code for details.

Author: Patrick Eriksson

Date: 2002-11-18

Definition at line 2121 of file ppath.cc.

References abs, Ppath::gp_lat, Ppath::gp_p, gridpos2gridrange(), gridpos_force_end_fd(), is_gridpos_at_index_i(), is_los_downwards(), Ppath::los, Ppath::np, plevel_angletilt(), plevel_slope_2d(), Ppath::pos, Ppath::r, refell2r(), rsurf_at_lat(), and RTOL.

Referenced by ppath_step_geom_2d(), and ppath_step_refr_2d().

◆ ppath_start_3d()

void ppath_start_3d	(	Numeric &	r_start,
		Numeric &	lat_start,
		Numeric &	lon_start,
		Numeric &	za_start,
		Numeric &	aa_start,
		Index &	ip,
		Index &	ilat,
		Index &	ilon,
		Numeric &	lat1,
		Numeric &	lat3,
		Numeric &	lon5,
		Numeric &	lon6,
		Numeric &	r15a,
		Numeric &	r35a,
		Numeric &	r36a,
		Numeric &	r16a,
		Numeric &	r15b,
		Numeric &	r35b,
		Numeric &	r36b,
		Numeric &	r16b,
		Numeric &	rsurface15,
		Numeric &	rsurface35,
		Numeric &	rsurface36,
		Numeric &	rsurface16,
		Ppath &	ppath,
		ConstVectorView	lat_grid,
		ConstVectorView	lon_grid,
		ConstTensor3View	z_field,
		ConstVectorView	refellipsoid,
		ConstMatrixView	z_surface
	)

ppath_start_3d

Internal help function for 3D path calculations.

The function does the asserts and determined some variables that are common for geometrical and refraction calculations.

See the code for details.

Author: Patrick Eriksson

Date: 2002-12-30

Definition at line 2353 of file ppath.cc.

References abs, Ppath::gp_lat, Ppath::gp_lon, Ppath::gp_p, gridpos(), gridpos2gridrange(), is_gridpos_at_index_i(), is_los_downwards(), Ppath::los, ConstVectorView::nelem(), Ppath::np, plevel_angletilt(), plevel_slope_3d(), Ppath::pos, Ppath::r, and refell2r().

Referenced by ppath_step_geom_3d(), and ppath_step_refr_3d().

◆ ppath_start_stepping()

void ppath_start_stepping	(	Ppath &	ppath,
		const Index &	atmosphere_dim,
		ConstVectorView	p_grid,
		ConstVectorView	lat_grid,
		ConstVectorView	lon_grid,
		ConstTensor3View	z_field,
		ConstVectorView	refellipsoid,
		ConstMatrixView	z_surface,
		const Index &	cloudbox_on,
		const ArrayOfIndex &	cloudbox_limits,
		const bool &	ppath_inside_cloudbox_do,
		ConstVectorView	rte_pos,
		ConstVectorView	rte_los,
		const Verbosity &	verbosity
	)

ppath_start_stepping

Initiates a Ppath structure for calculation of a path with ppath_step.

The function performs two main tasks. As mentioned above, it initiates a Ppath structure (a), but it also checks that the end point of the path is at an allowed location (b).

(a): The Ppath structure is set to hold the position and LOS of the last point of the path inside the atmosphere. This point is either the sensor position, or the point where the path leaves the model atmosphere. If the path is totally outside the atmosphere, no point is put into the structure. If the (practical) end and start points are identical, such as when the sensor is inside the cloud box, the background field is set.

(b): If it is found that the end point of the path is at an illegal position a detailed error message is given. Not allowed cases are:

The sensor is placed below surface level.
For 2D and 3D, the path leaves the model atmosphere at a latitude or longitude end face.
For 2D and 3D, the path is totally outside the atmosphere and the latitude and longitude of the tangent point is outside the range of the corresponding grids.

All input variables are identical with the WSV with the same name. The output variable is here called ppath for simplicity, but is in fact ppath_step.

Parameters

ppath	Output: A Ppath structure.
atmosphere_dim	The atmospheric dimensionality.
p_grid	The pressure grid.
lat_grid	The latitude grid.
lon_grid	The longitude grid.
z_field	The field of geometrical altitudes.
refellipsoid	As the WSV with the same name.
z_surface	Surface altitude.
cloudbox_on	Flag to activate the cloud box.
cloudbox_limits	Index limits of the cloud box.
ppath_inside_cloudbox_do	As the WSV with the same name.
rte_pos	The position of the sensor.
rte_los	The line-of-sight of the sensor.

Author: Patrick Eriksson

Date: 2002-05-17

Definition at line 4606 of file ppath.cc.

References abs, cart2poslos(), Ppath::constant, CREATE_OUT1, DEBUG_ONLY, dx, Ppath::end_los, Ppath::end_lstep, Ppath::end_pos, fractional_gp(), geometrical_ppc(), geompath_l_at_r(), geompath_lat_at_za(), geompath_za_at_r(), Ppath::gp_lat, Ppath::gp_lon, Ppath::gp_p, gridpos(), gridpos_check_fd(), gridpos_copy(), interp(), interpweights(), is_los_downwards(), joker, L_NOT_FOUND, LACC, Ppath::los, ConstVectorView::nelem(), Ppath::ngroup, Ppath::nreal, plevel_angletilt(), plevel_slope_2d(), plevel_slope_3d(), Ppath::pos, poslos2cart(), ppath_init_structure(), ppath_set_background(), Ppath::r, r_crossing_2d(), r_crossing_3d(), refell2d(), refell2r(), resolve_lon(), rte_pos2gridpos(), and RTOL.

Referenced by mcPathTraceGeneral(), mcPathTraceIPA(), and ppath_calc().

◆ ppath_step_geom_1d()

void ppath_step_geom_1d	(	Ppath &	ppath,
		ConstVectorView	z_field,
		ConstVectorView	refellipsoid,
		const Numeric &	z_surface,
		const Numeric &	lmax
	)

ppath_step_geom_1d

Calculates 1D geometrical propagation path steps.

This is the core function to determine 1D propagation path steps by pure geometrical calculations. Path points are included for crossings with the grids, tangent points and points of intersection with the surface. In addition, points are included in the propgation path to ensure that the distance along the path between the points does not exceed the selected maximum length (lmax). If lmax is <= 0, this means that no length criterion shall be applied.

Note that the input variables are here compressed to only hold data for a 1D atmosphere. For example, z_field is z_field(:,0,0).

For more information read the chapter on propagation paths in AUG.

Parameters

ppath	Output: A Ppath structure.
z_field	Geometrical altitudes corresponding to p_grid.
refellipsoid	As the WSV with the same name.
z_surface	Surface altitude.
lmax	Maximum allowed length between the path points.

Author: Patrick Eriksson

Date: 2002-05-20

Definition at line 2783 of file ppath.cc.

References Ppath::constant, do_gridrange_1d(), geometrical_ppc(), ConstVectorView::nelem(), ppath_end_1d(), and ppath_start_1d().

Referenced by ppath_stepGeometric().

◆ ppath_step_geom_2d()

void ppath_step_geom_2d	(	Ppath &	ppath,
		ConstVectorView	lat_grid,
		ConstMatrixView	z_field,
		ConstVectorView	refellipsoid,
		ConstVectorView	z_surface,
		const Numeric &	lmax
	)

ppath_step_geom_2d

Calculates 2D geometrical propagation path steps.

Works as the same function for 1D, despite that some input arguments are of different type.

Parameters

ppath	Output: A Ppath structure.
lat_grid	Latitude grid.
z_field	Geometrical altitudes
refellipsoid	As the WSV with the same name.
z_surface	Surface altitudes.
lmax	Maximum allowed length between the path points.

Author: Patrick Eriksson

Date: 2002-07-03

Definition at line 3136 of file ppath.cc.

References Ppath::constant, do_gridcell_2d_byltest(), geometrical_ppc(), ConstVectorView::nelem(), ppath_end_2d(), and ppath_start_2d().

Referenced by ppath_stepGeometric().

◆ ppath_step_geom_3d()

void ppath_step_geom_3d	(	Ppath &	ppath,
		ConstVectorView	lat_grid,
		ConstVectorView	lon_grid,
		ConstTensor3View	z_field,
		ConstVectorView	refellipsoid,
		ConstMatrixView	z_surface,
		const Numeric &	lmax
	)

ppath_step_geom_3d

Calculates 3D geometrical propagation path steps.

Works as the same function for 1D despite that some input arguments are of different type.

Parameters

ppath	Output: A Ppath structure.
lat_grid	Latitude grid.
lon_grid	Longitude grid.
z_field	Geometrical altitudes
refellipsoid	As the WSV with the same name.
z_surface	Surface altitudes.
lmax	Maximum allowed length between the path points.

Author: Patrick Eriksson

Date: 2002-12-30

Definition at line 3553 of file ppath.cc.

References Ppath::constant, do_gridcell_3d_byltest(), geometrical_ppc(), ConstVectorView::nelem(), ppath_end_3d(), and ppath_start_3d().

Referenced by mcPathTraceGeneral(), and ppath_stepGeometric().

◆ ppath_step_refr_1d()

void ppath_step_refr_1d	(	Workspace &	ws,
		Ppath &	ppath,
		ConstVectorView	p_grid,
		ConstTensor3View	z_field,
		ConstTensor3View	t_field,
		ConstTensor4View	vmr_field,
		ConstVectorView	f_grid,
		ConstVectorView	refellipsoid,
		const Numeric &	z_surface,
		const Numeric &	lmax,
		const Agenda &	refr_index_air_agenda,
		const String &	rtrace_method,
		const Numeric &	lraytrace
	)

ppath_step_refr_1d

Calculates 1D propagation path steps including effects of refraction.

This function works as the function ppath_step_geom_1d but considers also refraction. The upper length of the ray tracing steps is set by the argument lraytrace. This argument controls only the internal calculations. The maximum distance between the path points is still determined by lmax.

Parameters

ws	Current Workspace
ppath	Out: A Ppath structure.
p_grid	Pressure grid.
z_field	As the WSV with the same name.
t_field	As the WSV with the same name.
vmr_field	As the WSV with the same name.
f_grid	As the WSV with the same name.
refellipsoid	As the WSV with the same name.
z_surface	Surface altitude (1D).
lmax	Maximum allowed length between the path points.
refr_index_air_agenda	The WSV with the same name.
rtrace_method	String giving which ray tracing method to use. See the function for options.
lraytrace	Maximum allowed length for ray tracing steps.

Author: Patrick Eriksson

Date: 2002-11-26

Definition at line 3809 of file ppath.cc.

References Ppath::constant, get_refr_index_1d(), joker, Array< base >::nelem(), ppath_end_1d(), ppath_start_1d(), raytrace_1d_linear_basic(), and refraction_ppc().

Referenced by ppath_stepRefractionBasic().

◆ ppath_step_refr_2d()

void ppath_step_refr_2d	(	Workspace &	ws,
		Ppath &	ppath,
		ConstVectorView	p_grid,
		ConstVectorView	lat_grid,
		ConstTensor3View	z_field,
		ConstTensor3View	t_field,
		ConstTensor4View	vmr_field,
		ConstVectorView	f_grid,
		ConstVectorView	refellipsoid,
		ConstVectorView	z_surface,
		const Numeric &	lmax,
		const Agenda &	refr_index_air_agenda,
		const String &	rtrace_method,
		const Numeric &	lraytrace
	)

ppath_step_refr_2d

Calculates 2D propagation path steps, with refraction, using a simple and fast ray tracing scheme.

Works as the same function for 1D despite that some input arguments are of different type.

Parameters

ws	Current Workspace
ppath	Out: A Ppath structure.
p_grid	Pressure grid.
lat_grid	Latitude grid.
z_field	As the WSV with the same name.
t_field	As the WSV with the same name.
vmr_field	As the WSV with the same name.
f_grid	As the WSV with the same name.
refellipsoid	As the WSV with the same name.
z_surface	Surface altitudes.
lmax	Maximum allowed length between the path points.
refr_index_air_agenda	The WSV with the same name.
rtrace_method	String giving which ray tracing method to use. See the function for options.
lraytrace	Maximum allowed length for ray tracing steps.

Author: Patrick Eriksson

Date: 2002-12-02

Definition at line 4121 of file ppath.cc.

References joker, Array< base >::nelem(), ppath_end_2d(), ppath_start_2d(), and raytrace_2d_linear_basic().

Referenced by ppath_stepRefractionBasic().

◆ ppath_step_refr_3d()

void ppath_step_refr_3d	(	Workspace &	ws,
		Ppath &	ppath,
		ConstVectorView	p_grid,
		ConstVectorView	lat_grid,
		ConstVectorView	lon_grid,
		ConstTensor3View	z_field,
		ConstTensor3View	t_field,
		ConstTensor4View	vmr_field,
		ConstVectorView	f_grid,
		ConstVectorView	refellipsoid,
		ConstMatrixView	z_surface,
		const Numeric &	lmax,
		const Agenda &	refr_index_air_agenda,
		const String &	rtrace_method,
		const Numeric &	lraytrace
	)

ppath_step_refr_3d

Calculates 3D propagation path steps, with refraction, using a simple and fast ray tracing scheme.

Works as the same function for 1D despite that some input arguments are of different type.

Parameters

ws	Current Workspace
ppath	Out: A Ppath structure.
p_grid	Pressure grid.
lat_grid	Latitude grid.
lon_grid	Longitude grid.
z_field	Geometrical altitudes.
t_field	Atmospheric temperatures.
vmr_field	VMR values.
f_grid	As the WSV with the same name.
refellipsoid	As the WSV with the same name.
z_surface	Surface altitudes.
lmax	Maximum allowed length between the path points.
refr_index_air_agenda	The WSV with the same name.
rtrace_method	String giving which ray tracing method to use. See the function for options.
lraytrace	Maximum allowed length for ray tracing steps.

Author: Patrick Eriksson

Date: 2003-01-08

Definition at line 4466 of file ppath.cc.

References Array< base >::nelem(), ppath_end_3d(), ppath_start_3d(), and raytrace_3d_linear_basic().

Referenced by ppath_stepRefractionBasic().

◆ ppath_what_background()

Index ppath_what_background ( const Ppath & ppath )

ppath_what_background

Returns the case number for the radiative background.

See further the function ppath_set_background.

Returns: The case number.

Parameters

ppath A Ppath structure.

Author: Patrick Eriksson

Date: 2002-05-17

Definition at line 1835 of file ppath.cc.

References Ppath::background.

Referenced by cloud_ppath_update1D(), cloud_ppath_update1D_noseq(), defocusing_general_sub(), defocusing_sat2sat(), fos(), get_iy_of_background(), iwp_cloud_opt_pathCalc(), iyEmissionStandard(), iyRadioLink(), mcPathTraceGeneral(), ppath_append(), ppath_calc(), ppath_stepGeometric(), ppath_stepRefractionBasic(), and ppathFromRtePos2().

◆ r_crossing_2d()

void r_crossing_2d	(	Numeric &	lat,
		Numeric &	l,
		const Numeric &	r_hit,
		const Numeric &	r_start,
		const Numeric &	lat_start,
		const Numeric &	za_start,
		const Numeric &	ppc
	)

r_crossing_2d

Calculates where a 2D LOS crosses the specified radius.

The function only looks for crossings in the forward direction of the given zenith angle (neglecting all solutions giving l <= 0).

For cases with r_start <= r_hit and abs(za) > 90, the tangent point is passed and the returned crossing is on the other side of the tangent point.

LAT_NOT_FOUND and L_NOT_FOUND are returned if no solution is found.

Parameters

r	Out: Radius of found crossing.
lat	Out: Latitude of found crossing.
l	Out: Length along the path to the crossing.
r_hit	Radius of the level
r_start	Radius of start point.
lat_start	Latitude of start point.
za_start	Zenith angle at start point.
ppc	Propagation path constant

Author: Patrick Eriksson

Date: 2012-02-18

Definition at line 914 of file ppath.cc.

References abs, geompath_l_at_r(), geompath_lat_at_za(), geompath_za_at_r(), L_NOT_FOUND, LAT_NOT_FOUND, and sign().

Referenced by plevel_crossing_2d(), and ppath_start_stepping().

◆ r_crossing_3d()

void r_crossing_3d	(	Numeric &	lat,
		Numeric &	lon,
		Numeric &	l,
		const Numeric &	r_hit,
		const Numeric &	r_start,
		const Numeric &	lat_start,
		const Numeric &	lon_start,
		const Numeric &	za_start,
		const Numeric &	ppc,
		const Numeric &	x,
		const Numeric &	y,
		const Numeric &	z,
		const Numeric &	dx,
		const Numeric &	dy,
		const Numeric &	dz
	)

r_crossing_3d

Calculates where a 3D LOS crosses the specified radius

The solution algorithm is described in ATD. See the chapter on propagation paths.

The function only looks for crossings in the forward direction of the given zenith angle (neglecting all solutions giving l <= 0). Note that the tangent point can be passed.

LAT_NOT_FOUND, LON_NOT_FOUND and L_NOT_FOUND are returned if no solution is found.

Parameters

lat	Out: Latitude of found crossing.
lon	Out: Longitude of found crossing.
l	Out: Length along the path to the crossing.
r_hit	Target radius.
r_start	Radius of start point.
lat_start	Latitude of start point.
lon_start	Longitude of start point.
za_start	Zenith angle at start point.
ppc	Propagation path constant
x	x-coordinate of start position.
y	y-coordinate of start position.
z	z-coordinate of start position.
dx	x-part of LOS unit vector.
dy	y-part of LOS unit vector.
dz	z-part of LOS unit vector.

Author: Patrick Eriksson

Date: 2002-12-30

Definition at line 1638 of file ppath.cc.

References abs, ANGTOL, dx, L_NOT_FOUND, LAT_NOT_FOUND, LON_NOT_FOUND, max, min, q, and RAD2DEG.

Referenced by plevel_crossing_3d(), and ppath_start_stepping().

◆ raytrace_1d_linear_basic()

void raytrace_1d_linear_basic	(	Workspace &	ws,
		Array< Numeric > &	r_array,
		Array< Numeric > &	lat_array,
		Array< Numeric > &	za_array,
		Array< Numeric > &	l_array,
		Array< Numeric > &	n_array,
		Array< Numeric > &	ng_array,
		Index &	endface,
		ConstVectorView	p_grid,
		ConstVectorView	refellipsoid,
		ConstTensor3View	z_field,
		ConstTensor3View	t_field,
		ConstTensor4View	vmr_field,
		ConstVectorView	f_grid,
		const Numeric &	lmax,
		const Agenda &	refr_index_air_agenda,
		const Numeric &	lraytrace,
		const Numeric &	rsurface,
		const Numeric &	r1,
		const Numeric &	r3,
		Numeric	r,
		Numeric	lat,
		Numeric	za
	)

raytrace_1d_linear_basic

Performs ray tracing for 1D with linear steps.

A geometrical step with length of lraytrace is taken from each point. The zenith angle for the end point of that step is calculated considering the gradient of the refractive index. The length of the last ray tracing step is set to the distance to grid box boundary.

For more information read the chapter on propagation paths in AUG. The algorithm used is described in that part of ATD.

Parameters

ws	Current Workspace
r_array	Out: Radius of ray tracing points.
lat_array	Out: Latitude of ray tracing points.
za_array	Out: LOS zenith angle at ray tracing points.
l_array	Out: Distance along the path between ray tracing points.
n_array	Out: Refractive index at ray tracing points.
endface	Out: Number coding of exit face.
p_grid	The WSV with the same name.
refellipsoid	The WSV with the same name.
lat_grid	The WSV with the same name.
z_field	The WSV with the same name.
t_field	The WSV with the same name.
vmr_field	The WSV with the same name.
f_grid	As the WSV with the same name.
lmax	As the WSV ppath_lmax
refr_index_air_agenda	The WSV with the same name.
lraytrace	Maximum allowed length for ray tracing steps.
r_surface	Radius of the surface.
r1	Radius of lower pressure level.
r3	Radius of upper pressure level (r3 > r1).
r	Start radius for ray tracing.
lat	Start latitude for ray tracing.
za	Start zenith angle for ray tracing.

Author: Patrick Eriksson

Date: 2002-12-02

Definition at line 3658 of file ppath.cc.

References DEG2RAD, do_gridrange_1d(), geometrical_ppc(), geompath_l_at_r(), geompath_lat_at_za(), geompath_r_at_l(), geompath_za_at_r(), get_refr_index_1d(), ConstVectorView::nelem(), RAD2DEG, and refr_gradients_1d().

Referenced by ppath_step_refr_1d().

◆ raytrace_2d_linear_basic()

void raytrace_2d_linear_basic	(	Workspace &	ws,
		Array< Numeric > &	r_array,
		Array< Numeric > &	lat_array,
		Array< Numeric > &	za_array,
		Array< Numeric > &	l_array,
		Array< Numeric > &	n_array,
		Array< Numeric > &	ng_array,
		Index &	endface,
		ConstVectorView	p_grid,
		ConstVectorView	lat_grid,
		ConstVectorView	refellipsoid,
		ConstTensor3View	z_field,
		ConstTensor3View	t_field,
		ConstTensor4View	vmr_field,
		ConstVectorView	f_grid,
		const Numeric &	lmax,
		const Agenda &	refr_index_air_agenda,
		const Numeric &	lraytrace,
		const Numeric &	lat1,
		const Numeric &	lat3,
		const Numeric &	rsurface1,
		const Numeric &	rsurface3,
		const Numeric &	r1a,
		const Numeric &	r3a,
		const Numeric &	r3b,
		const Numeric &	r1b,
		Numeric	r,
		Numeric	lat,
		Numeric	za
	)

raytrace_2d_linear_basic

Performs ray tracing for 2D with linear steps.

A geometrical step with length of lraytrace is taken from each point. The zenith angle for the end point of that step is calculated considering the gradient of the refractive index. The length of the last ray tracing step is set to the distance to grid box boundary.

For more information read the chapter on propagation paths in AUG. The algorithm used is described in that part of ATD.

Parameters

ws	Current Workspace
r_array	Out: Radius of ray tracing points.
lat_array	Out: Latitude of ray tracing points.
za_array	Out: LOS zenith angle at ray tracing points.
l_array	Out: Distance along the path between ray tracing points.
n_array	Out: Refractive index at ray tracing points.
endface	Out: Number coding of exit face.
p_grid	The WSV with the same name.
lat_grid	The WSV with the same name.
refellipsoid	The WSV with the same name.
z_field	The WSV with the same name.
t_field	The WSV with the same name.
vmr_field	The WSV with the same name.
f_grid	As the WSV with the same name.
lmax	As the WSV ppath_lmax
refr_index_air_agenda	The WSV with the same name.
lraytrace	Maximum allowed length for ray tracing steps.
lat1	Latitude of left end face of the grid cell.
lat3	Latitude of right end face of the grid cell.
rsurface1	Radius for the surface at lat1.
rsurface3	Radius for the surface at lat3.
r1a	Radius of lower-left corner of the grid cell.
r3a	Radius of lower-right corner of the grid cell.
r3b	Radius of upper-right corner of the grid cell.
r1b	Radius of upper-left corner of the grid cell.
r	Start radius for ray tracing.
lat	Start latitude for ray tracing.
za	Start zenith angle for ray tracing.

Author: Patrick Eriksson

Date: 2002-12-02

Definition at line 3947 of file ppath.cc.

References abs, DEG2RAD, do_gridcell_2d_byltest(), geometrical_ppc(), geompath_l_at_r(), geompath_lat_at_za(), geompath_r_at_l(), geompath_za_at_r(), get_refr_index_2d(), ConstVectorView::nelem(), RAD2DEG, refr_gradients_2d(), and sign().

Referenced by ppath_step_refr_2d().

◆ raytrace_3d_linear_basic()

void raytrace_3d_linear_basic	(	Workspace &	ws,
		Array< Numeric > &	r_array,
		Array< Numeric > &	lat_array,
		Array< Numeric > &	lon_array,
		Array< Numeric > &	za_array,
		Array< Numeric > &	aa_array,
		Array< Numeric > &	l_array,
		Array< Numeric > &	n_array,
		Array< Numeric > &	ng_array,
		Index &	endface,
		ConstVectorView	refellipsoid,
		ConstVectorView	p_grid,
		ConstVectorView	lat_grid,
		ConstVectorView	lon_grid,
		ConstTensor3View	z_field,
		ConstTensor3View	t_field,
		ConstTensor4View	vmr_field,
		ConstVectorView	f_grid,
		const Numeric &	lmax,
		const Agenda &	refr_index_air_agenda,
		const Numeric &	lraytrace,
		const Numeric &	lat1,
		const Numeric &	lat3,
		const Numeric &	lon5,
		const Numeric &	lon6,
		const Numeric &	rsurface15,
		const Numeric &	rsurface35,
		const Numeric &	rsurface36,
		const Numeric &	rsurface16,
		const Numeric &	r15a,
		const Numeric &	r35a,
		const Numeric &	r36a,
		const Numeric &	r16a,
		const Numeric &	r15b,
		const Numeric &	r35b,
		const Numeric &	r36b,
		const Numeric &	r16b,
		Numeric	r,
		Numeric	lat,
		Numeric	lon,
		Numeric	za,
		Numeric	aa
	)

raytrace_3d_linear_basic

Performs ray tracing for 3D with linear steps.

A geometrical step with length of lraytrace is taken from each point. The zenith angle for the end point of that step is calculated considering the gradient of the refractive index. The length of the last ray tracing step is set to the distance to grid box boundary.

For more information read the chapter on propagation paths in AUG. The algorithm used is described in that part of ATD.

Parameters

ws	Current Workspace
r_array	Out: Radius of ray tracing points.
lat_array	Out: Latitude of ray tracing points.
lon_array	Out: Longitude of ray tracing points.
za_array	Out: LOS zenith angle at ray tracing points.
aa_array	Out: LOS azimuth angle at ray tracing points.
l_array	Out: Distance along the path between ray tracing points.
endface	Out: Number coding of exit face.
n_array	Out: Refractive index at ray tracing points.
lmax	As the WSV ppath_lmax
refr_index_air_agenda	The WSV with the same name.
lraytrace	Maximum allowed length for ray tracing steps.
refellipsoid	The WSV with the same name.
p_grid	The WSV with the same name.
lat_grid	The WSV with the same name.
lon_grid	The WSV with the same name.
z_field	The WSV with the same name.
t_field	The WSV with the same name.
vmr_field	The WSV with the same name.
f_grid	As the WSV with the same name.
lat1	Latitude of left end face of the grid cell.
lat3	Latitude of right end face of the grid cell.
lon5	Lower longitude of the grid cell.
lon6	Upper longitude of the grid cell.
rsurface15	Radius for the surface at lat1 and lon5.
rsurface35	Radius for the surface at lat3 and lon5.
rsurface36	Radius for the surface at lat3 and lon6.
rsurface16	Radius for the surface at lat1 and lon6.
r15a	Radius of corner: lower p-level,lat1 and lon5.
r35a	Radius of corner: lower p-level,lat3 and lon5.
r36a	Radius of corner: lower p-level,lat3 and lon6.
r16a	Radius of corner: lower p-level,lat1 and lon6.
r15b	Radius of corner: upper p-level,lat1 and lon5.
r35b	Radius of corner: upper p-level,lat3 and lon5.
r36b	Radius of corner: upper p-level,lat3 and lon6.
r16b	Radius of corner: upper p-level,lat1 and lon6.
r	Out: Start radius for ray tracing.
lat	Out: Start latitude for ray tracing.
lon	Out: Start longitude for ray tracing.
za	Out: Start zenith angle for ray tracing.
aa	Out: Start azimuth angle for ray tracing.

Author: Patrick Eriksson

Date: 2003-01-18

Definition at line 4258 of file ppath.cc.

References abs, adjust_los(), ANGTOL, cart2poslos(), DEG2RAD, do_gridcell_3d_byltest(), dx, geometrical_ppc(), get_refr_index_3d(), ConstVectorView::nelem(), poslos2cart(), RAD2DEG, refr_gradients_3d(), and resolve_lon().

Referenced by ppath_step_refr_3d().

◆ refraction_ppc()

Numeric refraction_ppc	(	const Numeric &	r,
		const Numeric &	za,
		const Numeric &	refr_index_air
	)

refraction_ppc

Calculates the propagation path constant for cases with refraction.

Both positive and negative zenith angles are handled.

Returns: Path constant.

Parameters

r	Radius.
za	LOS Zenith angle.
refr_index_air	Refractive index.

Author: Patrick Eriksson

Date: 2002-05-17

Definition at line 639 of file ppath.cc.

References abs, and DEG2RAD.

Referenced by ppath_step_refr_1d().

◆ resolve_lon()

void resolve_lon	(	Numeric &	lon,
		const Numeric &	lon5,
		const Numeric &	lon6
	)

resolve_lon

Resolves which longitude angle that shall be used.

Longitudes are allowed to vary between -360 and 360 degress, while the inverse trigonomtric functions returns values between -180 and 180. This function determines if the longitude shall be shifted -360 or +360 to fit the longitudes set by the user.

The argument lon as input is a value calculated by some inverse trigonometric function. The arguments lon5 and lon6 are the lower and upper limit for the probable range for lon. The longitude lon* will be shifted with -360 or +360 degrees if lon is significantly outside lon5 and lon6. No error is given if it is not possible to obtain a value between lon5 and lon6.

Parameters

lon	In/Out: Longitude, possible shifted when returned.
lon5	Lower limit of probable range for lon.
lon6	Upper limit of probable range for lon

Author: Patrick Eriksson

Date: 2003-01-05

Definition at line 675 of file ppath.cc.

Referenced by do_gridcell_3d(), do_gridcell_3d_byltest(), plevel_crossing_3d(), plevel_slope_3d(), ppath_start_stepping(), and raytrace_3d_linear_basic().

◆ rotationmat3D()

void rotationmat3D	(	Matrix &	R,
		ConstVectorView	vrot,
		const Numeric &	a
	)

rotationmat3D

Creates a 3D rotation matrix

Creates a rotation matrix such that R * x, operates on x by rotating x around the origin a radians around line connecting the origin to the point vrot.

The function is based on rotationmat3D.m, by Belechi (the function is found in atmlab).

Parameters

R	Out: Rotation matrix
vrot	Rotation axis
a	Rotation angle

Author: Bileschi and Patrick Eriksson

Date: 2009-10-02

Definition at line 520 of file ppath.cc.

References DEG2RAD, ConstMatrixView::ncols(), ConstVectorView::nelem(), ConstMatrixView::nrows(), and w().

Referenced by map_daa().

◆ rslope_crossing2d()

Numeric rslope_crossing2d	(	const Numeric &	rp,
		const Numeric &	za,
		const Numeric &	r0,
		Numeric	c1
	)

rslope_crossing2d

Calculates the angular distance to a crossing with a level having a radial slope.

The function solves the problem for a pressure level, or the planet's surface, where the radius changes linearly as a function of angle. No analytical solution to the original problem has been found. The problem involves sine and cosine of the latitude difference and these functions are replaced with their Taylor expansions where the two first terms are kept. This should be OK for most practical situations (the accuracy should be sufficient for values up to 1 degree?).

The problem and its solution is further described in AUG. See the chapter on propagation paths. The variable names below are the same as in AUG.

Both positive and negative zenith angles are handled.

The function only looks for crossings in the forward direction of the given zenith angle.

If the given path point is on the pressure level (rp=r0), the solution 0 is rejected. The latitude difference is set to 999 if no crossing exists.

The cases c=0, za=0 and za=180 are not allowed.

Returns: The angular distance to the crossing.

Parameters

rp	Radius of a point of the path inside the grid cell
za	Zenith angle of the path at rp.
r0	Radius of the pressure level or the surface at the latitude of rp.
c1	Linear slope term, as returned by plevel_slope_2d.

Author: Patrick Eriksson

Date: 2002-06-07

Definition at line 992 of file ppath.cc.

References abs, beta, DEG2RAD, dmin, LAT_NOT_FOUND, poly_root_solve(), RAD2DEG, and Matrix::resize().

Referenced by plevel_crossing_2d().

◆ rslope_crossing3d()

Numeric rslope_crossing3d	(	const Numeric &	rp,
		const Numeric &	za,
		const Numeric &	r0,
		Numeric	c1,
		Numeric	c2
	)

rslope_crossing3d

3D version of rslope_crossing2d.

Returns: The angular distance to the crossing.

Parameters

rp	Radius of a point of the path inside the grid cell
za	Zenith angle of the path at rp.
r0	Radius of the pressure level or the surface at the latitude of rp.
c1	Linear slope term, as returned by plevel_slope_3d.
c2	Quadratic slope term, as returned by plevel_slope_3d.

Author: Patrick Eriksson

Date: 2012-04-24

Definition at line 1511 of file ppath.cc.

References abs, beta, DEG2RAD, dmin, LAT_NOT_FOUND, poly_root_solve(), RAD2DEG, and Matrix::resize().

Referenced by plevel_crossing_3d().

◆ rsurf_at_lat()

Numeric rsurf_at_lat	(	const Numeric &	lat1,
		const Numeric &	lat3,
		const Numeric &	r1,
		const Numeric &	r3,
		const Numeric &	lat
	)

rsurf_at_lat

Determines the radius of a pressure level or the surface given the radius at the corners of a 2D grid cell.

Returns: Radius at the given latitude.

Parameters

lat1	Lower latitude of grid cell.
lat3	Upper latitude of grid cell.
r1	Radius at lat1
r3	Radius at lat3
lat	Latitude for which radius shall be determined.

Author: Patrick Eriksson

Date: 2010-03-12

Definition at line 743 of file ppath.cc.

Referenced by do_gridcell_2d_byltest(), plevel_crossing_2d(), and ppath_start_2d().

◆ rsurf_at_latlon()

Numeric rsurf_at_latlon	(	const Numeric &	lat1,
		const Numeric &	lat3,
		const Numeric &	lon5,
		const Numeric &	lon6,
		const Numeric &	r15,
		const Numeric &	r35,
		const Numeric &	r36,
		const Numeric &	r16,
		const Numeric &	lat,
		const Numeric &	lon
	)

rsurf_at_latlon

Determines the radius of a pressure level or the surface given the radius at the corners of a 3D grid cell.

Returns: Radius at the given latitude and longitude.

Parameters

lat1	Lower latitude of grid cell.
lat3	Upper latitude of grid cell.
lon5	Lower longitude of grid cell.
lon6	Upper longitude of grid cell.
r15	Radius at crossing of lat1 and lon5.
r35	Radius at crossing of lat3 and lon5.
r36	Radius at crossing of lat3 and lon6.
r16	Radius at crossing of lat1 and lon6.
lat	Latitude for which radius shall be determined.
lon	Longitude for which radius shall be determined.

Author: Patrick Eriksson

Date: 2002-12-30

Definition at line 1294 of file ppath.cc.

Referenced by do_gridcell_3d_byltest(), plevel_crossing_3d(), plevel_slope_3d(), and ppath_end_3d().

◆ zaaa2cart()

void zaaa2cart	(	Numeric &	dx,
		Numeric &	dy,
		Numeric &	dz,
		const Numeric &	za,
		const Numeric &	aa
	)

zaaa2cart

Converts zenith and azimuth angles to a cartesian unit vector.

This function and the sister function cart2zaaa handles transformation of line-of-sights. This in contrast to the sph/poslos functions that handles positions, or combinations of positions and line-of-sight.

The cartesian coordinate system used for these two functions can be defined as z : za = 0 x : za=90, aa=0 y : za=90, aa=90

Parameters

dx	Out: x-part of LOS unit vector.
dy	Out: y-part of LOS unit vector.
dz	Out: z-part of LOS unit vector.
za	LOS zenith angle at observation position.
aa	LOS azimuth angle at observation position.

Author: Patrick Eriksson

Date: 2009-10-02

Definition at line 484 of file ppath.cc.

References DEG2RAD, and dx.

Referenced by adjust_los(), map_daa(), propmat_clearskyAddZeeman(), and specular_losCalc().

Variable Documentation

◆ DEG2RAD

const Numeric DEG2RAD

extern

Referenced by geometrical_ppc(), geompath_r_at_za(), raytrace_1d_linear_basic(), raytrace_2d_linear_basic(), raytrace_3d_linear_basic(), refraction_ppc(), rotationmat3D(), rslope_crossing2d(), rslope_crossing3d(), and zaaa2cart().

◆ L_NOT_FOUND

const Numeric L_NOT_FOUND = 99e99

Definition at line 93 of file ppath.cc.

Referenced by do_gridcell_2d(), do_gridcell_3d(), lat_crossing_3d(), lon_crossing_3d(), plevel_crossing_2d(), plevel_crossing_3d(), ppath_start_stepping(), r_crossing_2d(), and r_crossing_3d().

◆ LACC

const Numeric LACC = 1e-5

Definition at line 88 of file ppath.cc.

Referenced by do_gridcell_2d_byltest(), do_gridcell_3d(), do_gridcell_3d_byltest(), and ppath_start_stepping().

◆ LAT_NOT_FOUND

const Numeric LAT_NOT_FOUND = 99e99

Definition at line 94 of file ppath.cc.

Referenced by lon_crossing_3d(), plevel_crossing_2d(), plevel_crossing_3d(), r_crossing_2d(), r_crossing_3d(), rslope_crossing2d(), and rslope_crossing3d().

◆ LATLONTOL

const Numeric LATLONTOL = 1e-8

Definition at line 83 of file ppath.cc.

Referenced by do_gridcell_2d_byltest(), and do_gridcell_3d_byltest().

◆ LON_NOT_FOUND

const Numeric LON_NOT_FOUND = 99e99

Definition at line 95 of file ppath.cc.

Referenced by lat_crossing_3d(), plevel_crossing_3d(), and r_crossing_3d().

◆ R_NOT_FOUND

const Numeric R_NOT_FOUND = -1

Definition at line 92 of file ppath.cc.

Referenced by lat_crossing_3d(), lon_crossing_3d(), plevel_crossing_2d(), and plevel_crossing_3d().

◆ RAD2DEG

const Numeric RAD2DEG

extern

Referenced by cart2zaaa(), geompath_za_at_r(), plevel_angletilt(), r_crossing_3d(), raytrace_1d_linear_basic(), raytrace_2d_linear_basic(), raytrace_3d_linear_basic(), rslope_crossing2d(), and rslope_crossing3d().

◆ RTOL

const Numeric RTOL = 1e-3

Definition at line 78 of file ppath.cc.

Referenced by do_gridcell_2d_byltest(), do_gridcell_3d_byltest(), do_gridrange_1d(), geompath_l_at_r(), geompath_za_at_r(), plevel_crossing_3d(), ppath_start_2d(), ppath_start_stepping(), and raytrace_1d_linear_basic().

Functions

Variables

Detailed Description

Function Documentation

◆ cart2zaaa()

◆ do_gridcell_2d_byltest()

◆ do_gridcell_3d_byltest()

◆ do_gridrange_1d()

◆ find_tanpoint()

◆ geometrical_ppc()

◆ geompath_from_r1_to_r2()

◆ geompath_l_at_r()

◆ geompath_lat_at_za()

◆ geompath_r_at_l()

◆ geompath_r_at_lat()

◆ geompath_r_at_za()

◆ geompath_za_at_r()

◆ is_los_downwards()

◆ map_daa()

◆ plevel_angletilt()

◆ plevel_crossing_2d()

◆ plevel_slope_2d() [1/2]

◆ plevel_slope_2d() [2/2]

◆ plevel_slope_3d() [1/2]

◆ plevel_slope_3d() [2/2]

◆ ppath_append()

◆ ppath_calc()

◆ ppath_copy()

◆ ppath_end_1d()

◆ ppath_end_2d()

◆ ppath_end_3d()

◆ ppath_init_structure()

◆ ppath_set_background()

◆ ppath_start_1d()

◆ ppath_start_2d()

◆ ppath_start_3d()

◆ ppath_start_stepping()

◆ ppath_step_geom_1d()

◆ ppath_step_geom_2d()

◆ ppath_step_geom_3d()

◆ ppath_step_refr_1d()

◆ ppath_step_refr_2d()

◆ ppath_step_refr_3d()

◆ ppath_what_background()

◆ r_crossing_2d()

◆ r_crossing_3d()

◆ raytrace_1d_linear_basic()

◆ raytrace_2d_linear_basic()

◆ raytrace_3d_linear_basic()

◆ refraction_ppc()

◆ resolve_lon()

◆ rotationmat3D()

◆ rslope_crossing2d()

◆ rslope_crossing3d()

◆ rsurf_at_lat()

◆ rsurf_at_latlon()

◆ zaaa2cart()

Variable Documentation

◆ DEG2RAD

◆ L_NOT_FOUND

◆ LACC

◆ LAT_NOT_FOUND

◆ LATLONTOL

◆ LON_NOT_FOUND

◆ R_NOT_FOUND

◆ RAD2DEG

◆ RTOL