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Workspace Method ppathCalcFromAltitude

Description

Moves rte_pos forwards to near altitude before calling ppathCalc
to compute a different ppath.  The accuracy-variable gives minimum
distance before the input altitude.

The forward-moving algorithm calls ppathCalc several
times at reduced maximum distances.  The intention is to maintain
the correct rte_los for a given rte_pos at all altitudes.  The
method is thus relatively slow, and VERY memory intense at low
accuracy.

Intended to be used with "tropospheric corrections" from ground
geometry.  Not well-tested

Throws error if no altitude is in line of sight.

Authors: Richard Larsson

Synopsis

ppathCalcFromAltitude(

ppath, ppath_agenda, ppath_lmax, ppath_lraytrace, atmgeom_checked, f_grid, cloudbox_on, cloudbox_checked, ppath_inside_cloudbox_do, rte_pos, rte_los, rte_pos2, altitude, accuracy )

Variables

OUT	ppath	(Ppath)	The propagation path for one line-of-sight.
IN	ppath_agenda	(Agenda)	Agenda calculating complete propagation paths.
IN	ppath_lmax	(Numeric)	Maximum length between points describing propagation paths.
IN	ppath_lraytrace	(Numeric)	Maximum length of ray tracing steps when determining propagation paths.
IN	atmgeom_checked	(Index)	OK-flag for the geometry of the model atmosphere.
IN	f_grid	(Vector)	The frequency grid for monochromatic pencil beam calculations.
IN	cloudbox_on	(Index)	Flag to activate the cloud box.
IN	cloudbox_checked	(Index)	OK-flag for variables associated with the cloudbox.
IN	ppath_inside_cloudbox_do	(Index)	Flag to perform ray tracing inside the cloudbox.
IN	rte_pos	(Vector)	A geographical position for starting radiative transfer calculations.
IN	rte_los	(Vector)	A line-of-sight for (complete) radiative transfer calculations.
IN	rte_pos2	(Vector)	A second geographical position to define the geometry for radiative transfer calculations.
GIN	altitude	(Numeric)	Altitude to move forward towards
GIN	accuracy	(Numeric, Default: 0.5)	Accuracy of altitude