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ppart_sw.md (4983B)

      1 # PPart\_SW
      2 
      3 The purpose of PPart\_SW is to perform radiative transfer computations
      4 using 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 not be used in the case of the SW domain.
     10 However, Rayleigh scattering is not actually taken into account by the
     11 code.
     12 It can be used as a toy-model in which only the transmission of incoming
     13 SW radiation is taken into account (as well as the emitted radiation
     14 when the atmosphere is hot enough).
     15 
     16 [![Spectrally integrated SW flux](images/si_flux.svg)](images/si_flux.svg)
     17 
     18 > Spectrally integrated SW flux profiles (upward, downward and net) as a
     19 > function of altitude for a Mid-Latitude Summer standard atmosphere.
     20 
     21 ## Quick start
     22 
     23 - Sources: [tarball](downloads/ppart_sw.tgz) /
     24            [pgp](downloads/ppart_sw.tgz.sig)
     25 
     26 ### Prerequisites
     27 
     28 Only a fortran compiler is needed (no external libraries).
     29 The `gfortran` compiler has been used for development.
     30 
     31 ### Installation
     32 
     33 Download and extract the archive (`tar -zxvf ppart_sw.tgz`); then move
     34 into the `PPart_SW` directory, and use the `make all` command to
     35 compile.
     36 You should use the `make clean` command in the case you want to
     37 recompile from scratch only (when include files are modified).
     38 If only source files are modified, the `make all` command will recompile
     39 modified files.
     40 
     41 ### Run
     42 
     43 PPart\_SW has been parallelized, which means you will have to launch it
     44 using the `mpirun` command:
     45 
     46     mpirun -np <NPROCS> ./PPart.exe
     47 
     48 with `<NPROCS>` the number of processes requested for the computation;
     49 MacOS users might encounter a error where the OS considers the user
     50 requested a number of processes higher than recommended.
     51 You can bypass it using the `-oversubscribe` option:
     52 
     53     mpirun -oversubscribe -np <NPROCS> ./PPart.exe
     54 
     55 ## Usage
     56 
     57 The code can run either using a pre-computed (and provided)
     58 k-distribution data set among 5 standard atmospheric profiles, or from a
     59 user-defined spectral data file.
     60 This user-defined spectral data file should be name `ecrad_opt_prop.txt`
     61 and located into the `data` directory.
     62 The format of this file can be found in the `/Doc/gas_opt_prop.pdf`
     63 documentation file, and a example `/Doc/input.for` source file provides
     64 a fortran subroutine for reading this file.
     65 A example `ecrad_opt_prop.txt` file is provided in the `/data` directory
     66 (for the Mid-Latitude Summer profile).
     67 
     68 Since this code has been adapted to the SW range, it also needs the
     69 incoming SW solar radiation at the top of the atmosphere.
     70 This data has to be provided in the `/data/incoming_sw.txt` input data
     71 file.
     72 A example file is provided in the case of the Earth atmosphere.
     73 It should be usable for other planets of the solar system by rescaling
     74 the values of the input solar flux.
     75 
     76 Simulation input is provided through the `data.in` and `options.in`
     77 files (located in the main `PPart_SW` directory):
     78 
     79 - the `options.in` file provides the possibility to use either a
     80   (provided) standard atmospheric data set or a user-defined spectral
     81   data set (in this case, the `/data/ecrad_opt_prop.txt` file has to be
     82   found).
     83   It provides the possibility to use a specular or diffuse reflective
     84   ground, and the possibility to perform the spectral integration over a
     85   limited number of spectral intervals.
     86   Then the user should specify whether a angular integration should be
     87   performed or a single-direction radiative transfer computation is
     88   required.
     89   Finally, the user can disable the computation of a NER matrix for
     90   every spectral interval.
     91 
     92 - the `data.in` file lets the user specify the spectral integration
     93   domain (if a limited spectral domain should be used), and the
     94   direction to use for a single-direction radiative transfer
     95   computation.
     96   Finally, the user should specify the index of the standard atmospheric
     97   profile to use, when the corresponding option has been selected.
     98 
     99 Results are located into the `/results` directory;
    100 several gnuplot scripts are provided in order to visualise various
    101 results.
    102 When a NER matrix has been computed for every spectral interval, a
    103 script named `anim.bash` can be found in the `/results/NER_animation`
    104 directory;
    105 this script will produce a animated gif of these NER matrices (the
    106 spectral interval evolving with time).
    107 This script requires the GraphicsMagick package.
    108 
    109 ## License
    110 
    111 Copyright © 2014-2018 |Méso|Star>
    112 ([contact@meso-star.com](mailto:contact@meso-star.com))  
    113 Copyright © 2010-2014 Institut Mines-Télécom Albi-Carmaux  
    114 Copyright © 2010-2014 Université Bordeaux 1
    115 
    116 PPart\_SW is free software released under the GPLv2+ license: GNU GPL version 2
    117 or later.
    118 You can freely study, modify or extend it.
    119 You are also welcome to redistribute it under certain conditions; refer
    120 to the
    121 [license](https://www.gnu.org/licenses/old-licenses/gpl-2.0.en.html) for
    122 details.