Python wrapper to the DISORT¹ radiative transfer solver.
(1) K. Stamnes, SC. Tsay, W. Wiscombe and K. Jayaweera, Numerically stable algorithm for discrete-ordinate-method radiative transfer in multiple scattering and emitting layered media, Appl Opt 27 (1988) (12), pp. 2502–2509.
Go to the directory where you have checked out the pyDISORT project and run the following command:
sudo python setup.py install
>>> import disort
>>> help(disort.run)
performs radiative transfer simulations by means of the DISORT RT solver
Parameters
----------
dTau : array
optical thickness in atmospheric layers
w0 : float, array
single scattering albedo (Default: 1.)
iphas : int, array
scattering phase function type (Default 2).
1 : Isotropic
2 : Rayleigh
3 : Henyey-Greenstein with asymmetry factor GG
4 : Haze L as specified by Garcia/Siewert
5 : Cloud C.1 as specified by Garcia/Siewert
gg : float, array
scattering asymmetry parameter (Default: 0.85)
umu0 : float
cosine of solar zenith angle (Default: 1.)
phi0 : float
solar azimuth angle (Default: 0.)
albedo : float
surface albedo (Default: 0.1)
fbeam : float
solar irradiance (Default: 1.)
utau : float, array
optical thickness where to output the RT fields (Default: 0.)
umu : float, array
cosine of viewing zenith angle where to output the RT fields (Default: 1.)
phi : float, array
viewing azimuth angle where to output the RT fields (Default: 0.)
maxmom : int
Max. number of Legendre coefficients. (Default: 299)
Nstr : int
Number of computational polar angles to be used
(= number of 'streams') ( should be even and .GE. 2 ).
(Default: 32)
temp : float, array
LEV = 0 to NLYR, Temperatures (K) of levels.
(Note that temperature is specified at LEVELS
rather than for layers.) Be sure to put top level
temperature in TEMPER(0), not TEMPER(1). Top and
bottom level values do not need to agree with top and
bottom boundary temperatures (i.e. temperature
discontinuities are allowed). (Default: 300.)
wvnmlo, wvnmhi : float
Wavenumbers (inv cm) of spectral interval of interest
( used only for calculating Planck function ).
Needed only if PLANK is TRUE, or in multiple runs, if
LAMBER is FALSE and BDREF depends on spectral interval.
(Default: wvnmlo=999., wvnmhi=1000.)
UsrTau : logical
= FALSE, Radiant quantities are to be returned
at boundary of every computational layer.
= TRUE, Radiant quantities are to be returned
at user-specified optical depths
(Default: True)
UsrAng : logical
= FALSE, Radiant quantities are to be returned
at computational polar angles.
= TRUE, Radiant quantities are to be returned
at user-specified polar angles.
(Default: True)
ibcnd : int
= 0, General case: boundary conditions any combination of:
* beam illumination from the top ( see FBEAM )
* isotropic illumination from the top ( see FISOT )
* thermal emission from the top ( see TEMIS, TTEMP )
* internal thermal emission sources ( see TEMPER )
* reflection at the bottom ( see LAMBER, ALBEDO, BDREF )
* thermal emission from the bottom ( see BTEMP )
= 1, Return only albedo and transmissivity of the entire
medium vs. incident beam angle; see S2 for details.
(Default: 0)
fisot : float
Intensity of top-boundary isotropic illumination.
[same units as PLKAVG (default W/sq m) if thermal
sources active, otherwise arbitrary units].
Corresponding incident flux is pi (3.14159...)
times FISOT.
(Default: 0.)
lamber : bool
= TRUE, isotropically reflecting bottom boundary.
= FALSE, bidirectionally reflecting bottom boundary.
(Default: True)
btemp : float
Temperature of bottom boundary (K) (bottom emissivity
is calculated from ALBEDO or function BDREF, so it need
not be specified). Needed only if PLANK is TRUE.
(Default: 300.)
ttemp : float
Temperature of top boundary (K).
Needed only if PLANK is TRUE.
(Default: 300.)
temis : float
Emissivity of top boundary.
Needed only if PLANK is TRUE.
(Default: 1.)
plank : bool
= TRUE, include thermal emission
= FALSE, ignore all thermal emission (saves computer time)
(Default: False)
onlyFl : bool
= TRUE, return fluxes, flux divergences, and mean
intensities.
= FALSE, return fluxes, flux divergences, mean
intensities, AND intensities.
(Default: False)
accur : float
Convergence criterion for azimuthal (Fourier cosine)
series. Will stop when the following occurs twice:
largest term being added is less than ACCUR times
total series sum. (Twice because there are cases where
terms are anomalously small but azimuthal series has
not converged.) Should be between 0 and 0.01 to avoid
risk of serious non-convergence. Has no effect on
problems lacking a beam source, since azimuthal series
has only one term in that case.
(Default: 0.)
PRNT : array(dtype=bool)
Array of LOGICAL print flags causing the following prints
L quantities printed
-- ------------------
1 input variables (except PMOM)
2 fluxes
3 intensities at user levels and angles
4 planar transmissivity and planar albedo
as a function solar zenith angle ( IBCND = 1 )
5 phase function moments PMOM for each layer
( only if PRNT(1) = TRUE, and only for layers
with scattering )
(Default: array([False False False False False]))
Returns
-------
ds_fields : list of arrays
[rfldir, rfldn, flup, dfdt, uavg, uu, albmed, trnmed]
rfldir : Downward Direct
rfldn : Downward Diffuse
flup : Upward Diffuse
dfdt : d(Net Flux) / d(Op Dep)
uu : Intensity
uavg : Mean intensity (including the direct beam)
(Not corrected for delta-M-scaling effects)
albmed : Albedo of the medium as a function of incident
beam angle cosine UMU(IU) (IBCND = 1 case only)
trnmed : Transmissivity of the medium as a function of incident
beam angle cosine UMU(IU) (IBCND = 1 case only)
Examples
--------
>>> import disort
>>> D_dir, D_diff, U_up, dFdt, I = disort.run(dTau, ssalb, iphas='Rayleigh')
See test directory.
-
The current implementation have the following parameters hardcoded:
- MXCLY = 50 (Max no. of computational layers)
- MXULV = 50 (Max no. of output levels)
- MXCMU = 48 (Max no. of computation polar angles)
- MXUMU = 10 (Max no. of output polar angles)
- MXPHI = 3 (Max no. of output azimuthal angles)
- MXSQT = 1000 (Max no. of square roots of integers (for LEPOLY))
-
These parameters are used as dimensions for array allocation. Allocation should be done dynamically