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Workspace Method MCRadar

Description

A radar 3D foward Monte Carlo radiative algorithm, that allows 
for 2D antenna patterns and arbitrary sensor positions.
Surface reflections are currently ignored.

The main output variable y and mc_error represent the
radar reflectivity integrated over the antenna function, and the
estimated error in this vector, respectively.

Unlike with yActive, the range bins gives the boundaries of 
the range bins as either round-trip time or distance from radar.

The WSV mc_y_tx gives the polarization state of the 
transmitter.

The WSV mc_max_scatorder prescribes the maximum scattering 
order to consider, after which `photon'-tracing will be
terminated. A value of one calculates only single scattering.

The WSV mc_max_iter describes the maximum number of `photons'
used in the simulation (more photons means smaller mc_error).
The method will terminate once the max_iter criterium is met.
If negative values are given for these parameters then it is
ignored.

Only "1" and "Ze" are allowed for iy_unit. The value of
mc_error follows the selection for iy_unit (both for in- and
output.

Authors: Ian S. Adams

Synopsis

MCRadar(

y, mc_error, mc_antenna, f_grid, f_index, sensor_pos, sensor_los, stokes_dim, atmosphere_dim, ppath_lmax, ppath_step_agenda, ppath_lraytrace, propmat_clearsky_agenda, p_grid, lat_grid, lon_grid, z_field, refellipsoid, z_surface, t_field, vmr_field, cloudbox_on, cloudbox_limits, pnd_field, scat_data, mc_y_tx, range_bins, atmfields_checked, atmgeom_checked, scat_data_checked, cloudbox_checked, iy_unit, mc_max_scatorder, mc_seed, mc_max_iter, ze_tref, k2, t_interp_order )

Variables

OUT	y	(Vector)	The measurement vector.
OUT	mc_error	(Vector)	Error in simulated y when using a Monte Carlo approach.
IN	mc_antenna	(MCAntenna)	Antenna pattern description for dedicated MC calculaions.
IN	f_grid	(Vector)	The frequency grid for monochromatic pencil beam calculations.
IN	f_index	(Index)	Frequency index.
IN	sensor_pos	(Matrix)	The sensor position for each measurement block.
IN	sensor_los	(Matrix)	The sensor line-of-sight (LOS) for each measurement block.
IN	stokes_dim	(Index)	The dimensionality of the Stokes vector (1-4).
IN	atmosphere_dim	(Index)	The atmospheric dimensionality (1-3).
IN	ppath_lmax	(Numeric)	Maximum length between points describing propagation paths.
IN	ppath_step_agenda	(Agenda)	Agenda calculating a propagation path step.
IN	ppath_lraytrace	(Numeric)	Maximum length of ray tracing steps when determining propagation paths.
IN	propmat_clearsky_agenda	(Agenda)	Agenda calculating the absorption coefficient matrices.
IN	p_grid	(Vector)	The pressure grid.
IN	lat_grid	(Vector)	The latitude grid.
IN	lon_grid	(Vector)	The longitude grid.
IN	z_field	(Tensor3)	The field of geometrical altitudes.
IN	refellipsoid	(Vector)	Reference ellipsoid.
IN	z_surface	(Matrix)	The surface altitude.
IN	t_field	(Tensor3)	The field of atmospheric temperatures.
IN	vmr_field	(Tensor4)	VMR field.
IN	cloudbox_on	(Index)	Flag to activate the cloud box.
IN	cloudbox_limits	(ArrayOfIndex)	The limits of the cloud box.
IN	pnd_field	(Tensor4)	Particle number density field.
IN	scat_data	(ArrayOfArrayOfSingleScatteringData)	Array of single scattering data.
IN	mc_y_tx	(Vector)	Normalized Stokes vector for transmission (e.g., radar).
IN	range_bins	(Vector)	The range bins of an active instrument.
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	cloudbox_checked	(Index)	OK-flag for variables associated with the cloudbox.
IN	iy_unit	(String)	Selection of output unit for some radiative transfer methods.
IN	mc_max_scatorder	(Index)	The maximum scattering order allowed for Monte Carlo radar calculations.
IN	mc_seed	(Index)	The integer seed for the random number generator used by Monte Carlo methods.
IN	mc_max_iter	(Index)	The maximum number of iterations allowed for Monte Carlo calculations.
GIN	ze_tref	(Numeric, Default: 273.15)	Reference temperature for conversion to Ze.
GIN	k2	(Numeric, Default: -1)	Reference dielectric factor.
GIN	t_interp_order	(Index, Default: 1)	Interpolation order of temperature for scattering data (so far only applied in phase matrix, not in extinction and absorption.