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Workspace Method iyRadarSingleScat
Description
Simulation of radar, restricted to single scattering.
The WSM treats e.g. radar measurements of cloud and precipitation,
on the condition that multiple scattering can be ignored. Beside
the direct back-scattering, the two-way attenuation by gases and
particles is considered. Surface scattering/clutter is ignored.
The method could potentially be used for lidars, but multiple
scattering poses here a must stronger constrain for the range of
applications.
The method shall be used with yRadar, NOT with yCalc.
The ppath provided should be calculated including cloudbox interior:
ppathCalc( cloudbox_on=0 )
The method returns the back-scattering for each point of ppath.
Several frequencies can be treated in parallel. The size of iy
is [ nf*np, stokes_dim ], where nf is the length of f_grid and
np is the number of path points. The data are stored in blocks
of [ np, stokes_dim ]. That is, all the results for the first
frequency occupy the np first rows of iy etc.
The polarisation state of the transmitted pulse is taken from
iy_transmitter. If the radar transmits several polarisations at
the same frequency, you need to handle this by using two frequencies
in f_grid, but these can be almost identical.
This method does not consider iy_unit_radar. Unit changes are instead
applied in *yRadar. The output of this method matches the option "1".
The extinction due to particles can be scaled (by *pext_scaling*),
which could be of interest when e.g. characterising inversions or
trying to compensate for ignored multiple scattering. The later is
commented further for particle_bulkpropRadarOnionPeeling.
For Jacobian calculations the default is to assume that the
transmittance is unaffected by the retrieval quantities. This is
done to save computational time, and should be a valid approximation
for the single-scattering conditions. Set *trans_in_jacobian* to 1 to
activate full Jacobian calculations.
Some auxiliary radiative transfer quantities can be obtained. Auxiliary
quantities are selected by iy_aux_vars and returned by iy_aux.
Valid choices for auxiliary data are:
"Radiative background": Index value flagging the radiative
background. The following coding is used: 0=space, 1=surface
and 2=cloudbox (the last case should not occur!). Only column
matching first Stokes element filled. Other columns are set to 0.
"Backscattering": The unattenuated back-scattering. That is, as
iy but with no attenuated applied. Here all columns are filled.
By combing iy and this auxiliary variable, the total two-way
attenuation can be derived.
"Abs species extinction": Extinction due to abs_species at each
ppath point, taken as the diagonal of the local extinction matrix.
"Particle extinction": Extinction due to particles at each
ppath point, taken as the diagonal of the local extinction matrix.
The retunred values includes *pext_scaling*
Authors: Patrick Eriksson
Synopsis
| iyRadarSingleScat( | iy, iy_aux, diy_dx, ppvar_p, ppvar_t, ppvar_vmr, ppvar_wind, ppvar_mag, ppvar_pnd, ppvar_f, stokes_dim, f_grid, atmosphere_dim, p_grid, t_field, nlte_field, vmr_field, abs_species, wind_u_field, wind_v_field, wind_w_field, mag_u_field, mag_v_field, mag_w_field, cloudbox_on, cloudbox_limits, pnd_field, dpnd_field_dx, scat_species, scat_data, scat_data_checked, iy_aux_vars, jacobian_do, jacobian_quantities, ppath, iy_transmitter, propmat_clearsky_agenda, water_p_eq_agenda, rte_alonglos_v, trans_in_jacobian, pext_scaling, t_interp_order ) |
Variables