ARTS built-in documentation server

Workspace Method MCGeneral

Description

A generalised 3D reversed Monte Carlo radiative algorithm, that
allows for 2D antenna patterns, surface reflection and arbitrary
sensor positions.

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

The WSV mc_max_iter describes the maximum number of `photons'
used in the simulation (more photons means smaller mc_error).
mc_std_err is the desired value of mc_error. mc_max_time is
the maximum allowed number of seconds for MCGeneral. The method
will terminate once any of the max_iter, std_err, max_time
criteria are met. If negative values are given for these
parameters then it is ignored.

The WSV mc_min_iter sets the minimum number of photons to apply
before the condition set by mc_std_err is considered. Values
of mc_min_iter below 100 are not accepted.

Negative values of mc_seed seed the random number generator
according to system time, positive mc_seed values are taken
literally.

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

Authors: Cory Davis

Synopsis

MCGeneral(

y, mc_iteration_count, mc_error, mc_points, mc_antenna, f_grid, f_index, sensor_pos, sensor_los, stokes_dim, atmosphere_dim, ppath_step_agenda, ppath_lraytrace, iy_space_agenda, surface_rtprop_agenda, 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_array_mono, atmfields_checked, atmgeom_checked, cloudbox_checked, mc_seed, iy_unit, mc_std_err, mc_max_time, mc_max_iter, mc_min_iter )

Variables

OUT	y	(Vector)	The measurement vector.
OUT	mc_iteration_count	(Index)	Counts the number of iterations (or photons) used in the MC scattering algorithm.
OUT	mc_error	(Vector)	Error in simulated y when using a Monte Carlo approach.
OUT	mc_points	(Tensor3)	Counts the number of MC endpoints in each grid cell.
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_step_agenda	(Agenda)	See agendas.cc.
IN	ppath_lraytrace	(Numeric)	Maximum length of ray tracing steps when determining propagation paths.
IN	iy_space_agenda	(Agenda)	See agendas.cc.
IN	surface_rtprop_agenda	(Agenda)	See agendas.cc.
IN	propmat_clearsky_agenda	(Agenda)	See agendas.cc.
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_array_mono	(ArrayOfSingleScatteringData)	Monochromatic single scattering data.
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	cloudbox_checked	(Index)	OK-flag for variables associated with the cloudbox.
IN	mc_seed	(Index)	The integer seed for the random number generator used by Monte Carlo methods.
IN	iy_unit	(String)	Selection of output unit for some radiative transfer methods.
IN	mc_std_err	(Numeric)	Target precision (1 std.
IN	mc_max_time	(Index)	The maximum time allowed for Monte Carlo calculations.
IN	mc_max_iter	(Index)	The maximum number of iterations allowed for Monte Carlo calculations.
IN	mc_min_iter	(Index)	The minimum number of iterations allowed for Monte Carlo calculations.