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Workspace Method ppathFixedLstep


Full propagation path calculation with fixed step length.

1. An active cloudbox is not handled (causes an error).
2. Observations of limb sounding type not handled. That is, zenith
   angles between 90 and about 120 deg will cause an error.
3. Unsuitable for downward observation from within the atmosphere.

The method determines the lowest point of the propagation path and
applies a fixed step length from that point. This point can be the
surface intersection or the sensor position depending on observation

There is no adjustment at the high altitude end, neither to the top
of the atmosphere altitude nor the sensor's altitude.

Default is to apply a step length of ppath_lmax everywhere.
By setting *za_scale* to 1, the step length is scaled with zenith
angle and the steps are rather constant in altitude spacing.

With *z_coarse* and *l_coarse* you can introduce another step length
at higher altitudes. If *z_coarse* is > 0, then *l_coarse* is applied
above *z_coarse*, instead of ppath_lmax. *za_scale* is considered
also for *l_coarse*.

Authors: Patrick Eriksson


ppathFixedLstep( ppath, atmfields_checked, atmgeom_checked, atmosphere_dim, lat_grid, lon_grid, z_field, refellipsoid, z_surface, cloudbox_on, rte_pos, rte_los, ppath_lmax, za_scale, z_coarse, l_coarse )


OUTppath(Ppath)The propagation path for one line-of-sight.
INatmfields_checked(Index)OK-flag for atmospheric grids and (physical) fields.
INatmgeom_checked(Index)OK-flag for the geometry of the model atmosphere.
INatmosphere_dim(Index)The atmospheric dimensionality (1-3).
INlat_grid(Vector)The latitude grid.
INlon_grid(Vector)The longitude grid.
INz_field(Tensor3)The field of geometrical altitudes.
INrefellipsoid(Vector)Reference ellipsoid.
INz_surface(Matrix)The surface altitude.
INcloudbox_on(Index)Flag to activate the cloud box.
INrte_pos(Vector)A geographical position for starting radiative transfer calculations.
INrte_los(Vector)A line-of-sight for (complete) radiative transfer calculations.
INppath_lmax(Numeric)Maximum length between points describing propagation paths.
GINza_scale(Index, Default: 0)Scale step length with 1/abs(cos(za)).
GINz_coarse(Numeric, Default: -1)Altitude for switching to coarse step length
GINl_coarse(Numeric, Default: 1e3)Coarse step length.