spec2tab.c

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/*
  This file is part of the IASI Code Collection.
  
  the IASI Code Collections 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.
  
  The IASI Code Collection 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 the IASI Code Collection. If not, see
  <http://www.gnu.org/licenses/>.
  
  Copyright (C) 2019-2026 Forschungszentrum Juelich GmbH
*/
 
#include "libiasi.h"
 
int main(
  int argc,
  char *argv[]) {
 
  static iasi_rad_t *iasi_rad;
 
  FILE *out;
 
  double dmin = 1e100, x0[3], x1[3];
 
  int ichan, track = -1, track2, xtrack = -1, xtrack2, format;
 
  /* Check arguments... */
  if (argc < 7)
    ERRMSG("Give parameters: <ctl> <iasi_l1b_file> "
           "[index <track> <xtrack> | geo <lon> <lat>] <spec.tab>");
 
  /* Read control parameters... */
  format = (int) scan_ctl(argc, argv, "FORMAT", -1, "1", NULL);
 
  /* Allocate... */
  ALLOC(iasi_rad, iasi_rad_t, 1);
 
  /* Read IASI data... */
  printf("Read IASI Level-1C data file: %s\n", argv[2]);
  iasi_read(format, argv[2], iasi_rad);
 
  /* Get indices... */
  if (argv[3][0] == 'i') {
    track = atoi(argv[4]);
    xtrack = atoi(argv[5]);
  }
 
  /* Find nearest footprint... */
  else {
    geo2cart(0, atof(argv[4]), atof(argv[5]), x0);
    for (track2 = 0; track2 < iasi_rad->ntrack; track2++)
      for (xtrack2 = 0; xtrack2 < L1_NXTRACK; xtrack2++) {
        geo2cart(0, iasi_rad->Longitude[track2][xtrack2],
                 iasi_rad->Latitude[track2][xtrack2], x1);
        if (DIST2(x0, x1) < dmin) {
          dmin = DIST2(x0, x1);
          track = track2;
          xtrack = xtrack2;
        }
      }
    if (dmin > 2500)
      ERRMSG("Geolocation not covered by granule!");
  }
 
  /* Check indices... */
  if (track < 0 || track >= iasi_rad->ntrack)
    ERRMSG("Along-track index out of range!");
  if (xtrack < 0 || xtrack >= L1_NXTRACK)
    ERRMSG("Across-track index out of range!");
 
  /* Create file... */
  printf("Write spectrum: %s\n", argv[6]);
  if (!(out = fopen(argv[6], "w")))
    ERRMSG("Cannot create file!");
 
  /* Write header... */
  fprintf(out,
          "# $1 = time (seconds since 01-JAN-2000, 00:00 UTC)\n"
          "# $2 = satellite longitude [deg]\n"
          "# $3 = satellite latitude [deg]\n"
          "# $4 = footprint longitude [deg]\n"
          "# $5 = footprint latitude [deg]\n"
          "# $6 = wavenumber [cm^-1]\n"
          "# $7 = brightness temperature [K]\n"
          "# $8 = radiance [W/(m^2 sr cm^-1)]\n\n");
 
  /* Write data... */
  for (ichan = 0; ichan < IASI_L1_NCHAN; ichan++)
    fprintf(out, "%.2f %g %g %g %g %g %g %g\n",
            iasi_rad->Time[track][xtrack],
            iasi_rad->Sat_lon[track],
            iasi_rad->Sat_lat[track],
            iasi_rad->Longitude[track][xtrack],
            iasi_rad->Latitude[track][xtrack],
            iasi_rad->freq[ichan],
            BRIGHT(iasi_rad->Rad[track][xtrack][ichan],
                   iasi_rad->freq[ichan]),
            iasi_rad->Rad[track][xtrack][ichan]);
 
  /* Close file... */
  fclose(out);
 
  /* Free... */
  free(iasi_rad);
 
  return EXIT_SUCCESS;
}