raytrace.c

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/*
  This file is part of JURASSIC.
  
  JURASSIC is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation, either version 3 of the License, or
  (at your option) any later version.
  
  JURASSIC is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.
  
  You should have received a copy of the GNU General Public License
  along with JURASSIC. If not, see <http://www.gnu.org/licenses/>.
  
  Copyright (C) 2003-2026 Forschungszentrum Juelich GmbH
*/
 
#include "jurassic.h"
 
/* ------------------------------------------------------------
   Functions...
   ------------------------------------------------------------ */
 
static void usage(
  void);
 
/* ------------------------------------------------------------
   Main...
   ------------------------------------------------------------ */
 
int main(
  int argc,
  char *argv[]) {
 
  static atm_t atm;
  static ctl_t ctl;
  static los_t los;
  static obs_t obs;
 
  FILE *out;
 
  char filename[2 * LEN], losbase[LEN];
 
  double u[NG];
 
  /* Print usage information... */
  USAGE;
 
  /* Check arguments... */
  if (argc < 5)
    ERRMSG("Missing or invalid command-line arguments.\n\n"
           "Usage: raytrace <ctl> <obs> <atm> <raytrace.tab> [KEY VALUE ...]\n\n"
           "Use -h for full help.");
 
  /* Read control parameters... */
  read_ctl(argc, argv, &ctl);
 
  /* Get basenames... */
  scan_ctl(argc, argv, "LOSBASE", -1, "los", losbase);
 
  /* Read observation geometry... */
  read_obs(NULL, argv[2], &ctl, &obs, 0);
 
  /* Read atmospheric data... */
  read_atm(NULL, argv[3], &ctl, &atm, 0);
 
  /* Write info... */
  LOG(1, "Write raytrace data: %s", argv[4]);
 
  /* Create file... */
  if (!(out = fopen(argv[4], "w")))
    ERRMSG("Cannot create file!");
 
  /* Write header... */
  fprintf(out,
          "# $1 = time (seconds since 2000-01-01T00:00Z)\n"
          "# $2 = observer altitude [km]\n"
          "# $3 = observer longitude [deg]\n"
          "# $4 = observer latitude [deg]\n"
          "# $5 = view point altitude [km]\n"
          "# $6 = view point longitude [deg]\n"
          "# $7 = view point latitude [deg]\n"
          "# $8 = tangent point altitude [km]\n"
          "# $9 = tangent point longitude [deg]\n"
          "# $10 = tangent point latitude [deg]\n"
          "# $11 = ray path index\n" "# $12 = ray path length [km]\n");
  for (int ig = 0; ig < ctl.ng; ig++)
    fprintf(out, "# $%d = %s column density [molec/cm^2]\n",
            13 + ig, ctl.emitter[ig]);
  fprintf(out, "\n");
 
  /* Loop over rays... */
  for (int ir = 0; ir < obs.nr; ir++) {
 
    /* Raytracing... */
    raytrace(&ctl, &atm, &obs, &los, ir);
 
    /* Set filename data... */
    sprintf(filename, "%s.%d.tab", losbase, ir);
 
    /* Write info... */
    LOG(1, "Write LOS data: %s", filename);
 
    /* Create file... */
    FILE *out2;
    if (!(out2 = fopen(filename, "w")))
      ERRMSG("Cannot create file!");
 
    /* Write header... */
    fprintf(out2,
            "# $1 = time (seconds since 2000-01-01T00:00Z)\n"
            "# $2 = altitude [km]\n"
            "# $3 = longitude [deg]\n"
            "# $4 = latitude [deg]\n"
            "# $5 = pressure [hPa]\n" "# $6 = temperature [K]\n");
    for (int ig = 0; ig < ctl.ng; ig++)
      fprintf(out2, "# $%d = %s volume mixing ratio [ppv]\n",
              7 + ig, ctl.emitter[ig]);
    for (int iw = 0; iw < ctl.nw; iw++)
      fprintf(out2, "# $%d = extinction (window %d) [km^-1]\n",
              7 + ctl.ng + iw, iw);
    fprintf(out2, "\n");
 
    /* Write data... */
    for (int ip = 0; ip < los.np; ip++) {
      fprintf(out2, "%.2f %g %g %g %g %g", obs.time[ir], los.z[ip],
              los.lon[ip], los.lat[ip], los.p[ip], los.t[ip]);
      for (int ig = 0; ig < ctl.ng; ig++)
        fprintf(out2, " %g", los.q[ip][ig]);
      for (int iw = 0; iw < ctl.nw; iw++)
        fprintf(out2, " %g", los.k[ip][iw]);
      fprintf(out2, "\n");
    }
 
    /* Close file... */
    fclose(out2);
 
    /* Get column densities... */
    double s = 0;
    for (int ig = 0; ig < ctl.ng; ig++)
      u[ig] = 0;
    for (int ip = 0; ip < los.np; ip++) {
      s += los.ds[ip];
      for (int ig = 0; ig < ctl.ng; ig++)
        u[ig] += los.u[ip][ig];
    }
 
    /* Write summary data... */
    fprintf(out, "%.2f %g %g %g %g %g %g %g %g %g %d %g",
            obs.time[ir], obs.obsz[ir], obs.obslon[ir], obs.obslat[ir],
            obs.vpz[ir], obs.vplon[ir], obs.vplat[ir],
            obs.tpz[ir], obs.tplon[ir], obs.tplat[ir], ir, s);
    for (int ig = 0; ig < ctl.ng; ig++)
      fprintf(out, " %g", u[ig]);
    fprintf(out, "\n");
  }
 
  /* Close file... */
  fclose(out);
 
  return EXIT_SUCCESS;
}
 
/*****************************************************************************/
 
static void usage(
  void) {
  printf("\nJURASSIC ray-tracing tool.\n\n");
  printf("Determine atmospheric line-of-sight paths and write a summary\n");
  printf("table plus one LOS profile file per ray.\n\n");
  printf("Usage:\n");
  printf("  raytrace <ctl> <obs> <atm> <raytrace.tab> [KEY VALUE ...]\n\n");
  printf("Arguments:\n");
  printf("  <ctl>           Control file.\n");
  printf("  <obs>           Observation geometry input file.\n");
  printf("  <atm>           Atmospheric state input file.\n");
  printf("  <raytrace.tab>  Output summary table for traced rays.\n");
  printf("  [KEY VALUE]     Optional control parameters.\n\n");
  printf("Tool-specific control parameters:\n");
  printf("  LOSBASE <name>  Basename for per-ray LOS output files.\n\n");
  printf("Common control parameters:\n");
  printf("  ATMFMT, OBSFMT         Input file formats.\n");
  printf("  NG, EMITTER[i]         Active emitters.\n");
  printf
    ("  ND, NU[i]              Spectral channels in observation files.\n");
  printf("  NW, WINDOW[i]          Extinction-window layout.\n");
  printf("  REFRAC, RAYDS, RAYDZ   Ray-tracing settings.\n\n");
  printf("Further information:\n");
  printf("  Manual: https://slcs-jsc.github.io/jurassic/\n");
}