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Workspace Method DisortCalcIrradiance

Description

Interface to the DISORT scattering solver (by Stamnes et al.).
for running flux (irradiance) calculations

It provides the irradiance field from a scalar
1D scattering solution assuming a plane-parallel atmosphere (flat
Earth). Only totally randomly oriented particles are allowed.
Refraction is not taken into account. Only Lambertian surface
reflection is handled.

*nstreams* is the number of polar angles taken into account
internally in the scattering solution and for the angular integration.
*nstreams* determines the angular resolution, hence the accuracy,
of the scattering solution. The more anisotropic the bulk scattering
matrix, the more streams are required. The computational burden
increases approximately linearly with *nstreams*. The default value
(6) is sufficient for most flux calculations.

Some auxiliary quantities can be obtained. Auxiliary
quantities are selected by disort_aux_vars and returned by disort_aux.
Valid choices for auxiliary data are:
 "Layer optical thickness": Matrix [f_grid, size of p_grid - 1] layer optical
                              thickness.
 "Single scattering albedo": Matrix [f_grid, size of p_grid - 1] layer single"
                               scattering albedo.
 "Direct downward spectral irradiance": Matrix [f_grid, p_grid]. 
                               Direct downward spectral irradiance.
                               Zero, if no sun is present. 
 "dFdtau": Matrix [f_grid, p_grid]. Flux divergence in optical 
                               thickness space.

Authors: Manfred Brath

Synopsis

DisortCalcIrradiance(

spectral_irradiance_field, disort_aux, atmfields_checked, atmgeom_checked, scat_data_checked, propmat_clearsky_agenda, gas_scattering_agenda, atmosphere_dim, pnd_field, t_field, z_field, vmr_field, p_grid, lat_true, lon_true, refellipsoid, scat_data, suns, f_grid, stokes_dim, z_surface, surface_skin_t, surface_scalar_reflectivity, gas_scattering_do, suns_do, disort_aux_vars, nstreams, Npfct, only_tro, quiet, emission, intensity_correction )

Variables

OUT	spectral_irradiance_field	(Tensor5)	Spectral irradiance field.
OUT	disort_aux	(ArrayOfMatrix)	Auxilary data to the output of the DisortCalc-Methods.
IN	atmfields_checked	(Index)	OK-flag for atmospheric grids and (physical) fields.
IN	atmgeom_checked	(Index)	OK-flag for the geometry of the model atmosphere.
IN	scat_data_checked	(Index)	OK-flag for scat_data.
IN	propmat_clearsky_agenda	(Agenda)	Agenda calculating the absorption coefficient matrices.
IN	gas_scattering_agenda	(Agenda)	Agenda calculating gas scattering extinction and phase matrix.
IN	atmosphere_dim	(Index)	The atmospheric dimensionality (1-3).
IN	pnd_field	(Tensor4)	Particle number density field.
IN	t_field	(Tensor3)	The field of atmospheric temperatures.
IN	z_field	(Tensor3)	The field of geometrical altitudes.
IN	vmr_field	(Tensor4)	VMR field.
IN	p_grid	(Vector)	The pressure grid.
IN	lat_true	(Vector)	Latitudinal geolocation for 1D and 2D data.
IN	lon_true	(Vector)	Longitudinal geolocation for 1D and 2D data.
IN	refellipsoid	(Vector)	Reference ellipsoid.
IN	scat_data	(ArrayOfArrayOfSingleScatteringData)	Array of single scattering data.
IN	suns	(ArrayOfSun)	Array of Sun.
IN	f_grid	(Vector)	The frequency grid for monochromatic pencil beam calculations.
IN	stokes_dim	(Index)	The dimensionality of the Stokes vector (1-4).
IN	z_surface	(Matrix)	The surface altitude.
IN	surface_skin_t	(Numeric)	Surface skin temperature.
IN	surface_scalar_reflectivity	(Vector)	Surface reflectivity, assuming it can be described as a scalar value.
IN	gas_scattering_do	(Index)	Flag to activate gas scattering.
IN	suns_do	(Index)	Flag to activate the sun(s).
IN	disort_aux_vars	(ArrayOfString)	Selection of quantities for disort_aux .
GIN	nstreams	(Index, Default: 6)	Number of polar angle directions (streams) in DISORT solution (must be an even number).
GIN	Npfct	(Index, Default: 181)	Number of angular grid points to calculate bulk phase function on (and derive Legendre polynomials from). If <0, the finest za_grid from scat_data will be used.
GIN	only_tro	(Index, Default: 0)	Set to 1 if the scattering data is just of TRO type. Has effect only if Npfct > 3 or Npfct<0, but then leads to much faster calculations.
GIN	quiet	(Index, Default: 0)	Silence C Disort warnings.
GIN	emission	(Index, Default: 1)	Enables blackbody emission. Set to zero, if no Emission e. g. like in visible regime for earth is needed
GIN	intensity_correction	(Index, Default: 1)	Enables intensity correction. Importantant for low number of streams. Set to zero, if problems encounter or using a high number of streams (>30)