Location of file defining water cloud properties.
wc_file type file
type defines the file type, which can be one of the
following:
- 1D
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Location of file defining one-dimensional profile.
The file must contain three columns: Column 1 is the altitude in km, column 2 the liquid water content (LWC) in grams per cubic meter, and column 3 the effective droplet radius in micrometer. Empty lines are ignored. Comments start with #. Note that the definition of cloud altitudes in wc_file 1D refers to sea level, not to altitude above ground. E.g., when altitude is set to 1.63km, and the first cloud level is defined at 3km, the cloud would start at 1.37km above ground. An example of a water cloud is given in examples/WC.DAT.
Per default the cloud properties are interpreted as layer properties. Before version 1.4 the default was level properties: The optical depth of a layer was calculated using information from the upper and lower levels defining the layer. To switch to the old behaviour, use interpret_as_level. See section about water clouds for a realistic example how the contents of the wc_file 1D are converted to optical properties.
- 3D
-
Define a MYSTIC 3D water cloud input file. In case the rte_solver is not mystic, independent column calculations are performed for the 3D field. (See examples/UVSPEC_WC_IPA.INP for an example.) The expected format of the cloud file is:
Nx Ny Nz flag
dx dy z(1) z(2) ... z(n)
ix iy iz ext g ssa (if flag == 1)
ix iy iz ext reff (if flag == 2)
ix iy iz LWC reff (if flag == 3)
where Nx, Ny and Nz are the number of grid boxes in x, y, and z-direction. The parameter flag determines the format of the 3rd and following lines. In the second line dx and dy are the sizes of the boxes in x- and y-direction in km. In the third and following lines the indices ix, iy, and iz specify cloudy pixels. The optical properties of the cloud, are given by the other parameters in the line, where ext is the extinction coefficient [1/km], g the asymmetry parameter, reff the effective radius [micrometer], and ssa the single scattering albedo. The conversion from microphysical to optical properties is defined by wc_properties (identical to the 1D case). Note that the first dimension (x) propagates east, and the second dimension (y) north. For more information see section . - ipa
-
Define a 3D input file. Independent column calculations are performed for the 3D field. As argument a name of a 3D cloud file must be given. This file has to be in the format as needed by MYSTIC, see wc_file 3D. (See examples/UVSPEC_WC_IPA.INP for an example.)
- ipa_files
-
A two-column file, defining water cloud property files (see wc_file 1D) in the first column and the correspoding weights in the second column. The radiative transfer calculation is performed independently for each cloud column and the result is the weighted average of all independent columns. If ic_file ipa_files and wc_file ipa_files are both defined, both must have the same columns in the same order, otherwise uvspec will complain. See examples/UVSPEC_WC_IC_IPA_FILES.INP for an example.
- moments
-
A way to specify water cloud extinction coefficient, single scattering albedo, and scattering phase function for each layer.
The file specified by wc_file moments has two columns where column 1 is the altitude in km. The second column is the name of a file which defines the optical properties of the layer starting at the given altitude. The files specified in the second column must have the following format:
-
Column 1: The wavelength in nm. These wavelengths may be different from those in source solar filename. Optical properties are interpolated to the requested wavelengths.
-
Column 2: The extinction coefficient of the layer in units km-1.
-
Column 3: The single scattering albedo of the layer.
-
Column 4-(nmom+4): The moments of the scattering phase function.
Note that if using the rte_solver cdisort or rte_solver fdisort2 it makes good sense to make the number of moments larger than number_of_streams because all moments are used in the calculation. For rte_solver fdisort1 and rte_solver polradtran the number of moments included in the calculations will be number_of_streams+1. Higher order moments will be ignored for these solvers. Please note that the uppermost line of the wc_file moments denotes simply the top altitude of the uppermost layer. The optical properties of this line are consequently ignored. There are two options for this line: either an optical property file with zero optical thickness is specified or ”NULL” instead.
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