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ppart_lw.md (4363B)

      1 # PPart\_LW
      2 
      3 The purpose of PPart\_LW is to perform radiative transfer computations using
      4 k-distribution data sets (that can be produced by
      5 [Kdistribution](kdistribution.html), or any other code).
      6 This code is based on analytic radiative transfer solutions that are
      7 valid only in the case of a emitting and absorbing, but non-scattering,
      8 atmosphere.
      9 This code should therefore be used, in the case of the terrestrial
     10 atmosphere, for clear-sky LW computations only.
     11 
     12 [![Brightness temperature](images/Tb.svg)](images/Tb.svg)
     13 
     14 >   Brightness temperature in the [4-20] micrometers range, for a
     15 >   Mid-Latitude Summer standard atmospheric profile.
     16 
     17 ## Quick start
     18 
     19 - Sources: [tarball](downloads/ppart_lw.tgz) /
     20            [pgp](downloads/ppart_lw.tgz.sig)
     21 
     22 ### Prerequisites
     23 
     24 Only a fortran compiler is needed (no external libraries).
     25 The `gfortran` compiler has been used for development.
     26 
     27 ### Installation
     28 
     29 Download and extract the archive (`tar -zxvf ppart_lw.tgz`); then move
     30 into the `PPart_LW` directory, and use the `make all` command to
     31 compile.
     32 You should use the `make clean` command in the case you want to
     33 recompile from scratch only (when include files are modified).
     34 If only source files are modified, the `make all` command will recompile
     35 modified files.
     36 
     37 ### Run
     38 
     39 PPart\_LW has been parallelized, which means you will have to launch it
     40 using the `mpirun` command:
     41 
     42     mpirun -np <NPROCS> ./PPart.exe
     43 
     44 with `<NPROCS>` the number of processes requested for the
     45 computation;
     46 MacOS users might encounter a error where the OS considers the user
     47 requested a number of processes higher than recommended.
     48 You can bypass it using the `-oversubscribe` option:
     49 
     50     mpirun -oversubscribe -np <NPROCS> ./PPart.exe
     51 
     52 ## Usage
     53 
     54 The code can run either using a pre-computed (and provided)
     55 k-distribution data set among 5 standard atmospheric profiles, or from a
     56 user-defined spectral data file.
     57 This user-defined spectral data file should be name
     58 `ecrad_opt_prop.txt`, and located into the `/data` directory. The format
     59 of this file can be found in the `/Doc/gas_opt_prop.pdf` documentation
     60 file, and a example `/Doc/input.for` source file provides a fortran
     61 subroutine for reading this file.
     62 An example `ecrad_opt_prop.txt` file is provided in the `/data`
     63 directory (for the Mid-Latitude Summer profile).
     64 
     65 Simulation input is provided through the `data.in` and `options.in`
     66 files (located in the main `PPart_LW` directory):
     67 
     68 - the `options.in` file provides the possibility to use either a
     69   (provided) standard atmospheric data set or a user-defined spectral
     70   data set (in this case, the `/data/ecrad_opt_prop.txt` file has to be
     71   found).
     72   It provides the possibility to use a specular or diffuse reflective
     73   ground, and the possibility to perform the spectral integration over a
     74   limited number of spectral intervals.
     75   Then the user should specify whether a angular integration should be
     76   performed or a single-direction radiative transfer computation is
     77   required.
     78   Finally, the user can disable the computation of a NER matrix for
     79   every spectral interval.
     80 
     81 - the `data.in` file lets the user specify the spectral integration
     82   domain (if a limited spectral domain should be used), and the
     83   direction to use for a single-direction radiative transfer
     84   computation.
     85   Finally, the user should specify the index of the standard atmospheric
     86   profile to use, when the corresponding option has been selected.
     87 
     88 Results are located into the `/results` directory; several gnuplot
     89 scripts are provided in order to visualise various results.
     90 When a NER matrix has been computed for every spectral interval, a
     91 script named `anim.bash` can be found in the `/results/NER_animation`
     92 directory;
     93 this script will produce a animated gif of these NER matrices (the
     94 spectral interval evolving with time).
     95 This script requires the GraphicsMagick package.
     96 
     97 
     98 ## License
     99 
    100 Copyright © 2014-2018 |Méso|Star>
    101 ([contact@meso-star.com](mailto:contact@meso-star.com))  
    102 Copyright © 2010-2014 Institut Mines-Télécom Albi-Carmaux  
    103 Copyright © 2010-2014 Université Bordeaux 1
    104 
    105 PPart\_LW is free software released under the GPLv2+ license: GNU GPL version 2
    106 or later.
    107 You can freely study, modify or extend it.
    108 You are also welcome to redistribute it under certain conditions; refer
    109 to the
    110 [license](https://www.gnu.org/licenses/old-licenses/gpl-2.0.en.html) for
    111 details.