NASA Ocean Color

ocssw V2022

 /* ============================================================================ */
 /* module l1_l1c.c - functions to read L1C for l2gen (l1info really)            */
 /* Written By:  Don Shea                                                        */
 /*                                                                              */
 /* ============================================================================ */
  
 #include <netcdf.h>
 #include "l1_l1c.h"
  
 #include <nc4utils.h>
 #include "libnav.h"
 #include <stdio.h>
 #include <math.h>
  
  
 static short *tmpShort;
  
 static size_t num_scans, num_pixels;
 static size_t num_bands;
 static int ncid_L1C;
  
 // time
 static double *scan_time;
 static double file_start_day;
  
 // geolocation data
 static int geolocationGrp;
 static int lonId, latId;
 static float latFillValue = BAD_FLT;
 static float lonFillValue = BAD_FLT;
  
 int openl1_l1c(filehandle * file) {
     int dimid, status;
     
     // Open the netcdf4 input file
     printf("Opening L1C file\n");
     status = nc_open(file->name, NC_NOWRITE, &ncid_L1C);
     if (status != NC_NOERR) {
         fprintf(stderr, "-E- %s line %d: nc_open(%s) failed.\n",
                 __FILE__, __LINE__, file->name);
         return (1);
     }
     
     // num_scans
     status = nc_inq_dimid(ncid_L1C, "bins_along_track", &dimid);
     if (status != NC_NOERR) {
         fprintf(stderr, "-E- Error reading bins_along_track.\n");
         exit(EXIT_FAILURE);
     }
     nc_inq_dimlen(ncid_L1C, dimid, &num_scans);
  
     // num_pixels
     status = nc_inq_dimid(ncid_L1C, "bins_across_track", &dimid);
     if (status != NC_NOERR) {
         fprintf(stderr, "-E- Error reading bins_across_track.\n");
         exit(EXIT_FAILURE);
     }
     nc_inq_dimlen(ncid_L1C, dimid, &num_pixels);
  
     // num_bands
     status = nc_inq_dimid(ncid_L1C, "intensity_bands_per_view", &dimid);
     if (status != NC_NOERR) {
         fprintf(stderr, "-E- Error reading intensity_bands_per_view.\n");
         exit(EXIT_FAILURE);
     }
     nc_inq_dimlen(ncid_L1C, dimid, &num_bands);
  
     if (want_verbose) {
         printf("L1C Npix  :%d Nlines:%d\n", (int)num_pixels, (int)num_scans);
     } // want_verbose
  
     // allocate all of the data
     tmpShort = (short*) malloc(num_pixels * sizeof(short));
     scan_time = (double*) malloc(num_scans * sizeof(double));
  
     // Get group id from L1B file for GROUP bin_attributes.
     int groupid;
     if ((nc_inq_grp_ncid(ncid_L1C, "bin_attributes", &groupid)) == NC_NOERR) {
     } else {
         fprintf(stderr, "-E- Error finding bin_attributes.\n");
         exit(EXIT_FAILURE);
     }  
     int varid;
     double scan_timeFillValue = BAD_FLT;
     status = nc_inq_varid(groupid, "nadir_view_time", &varid);
     if(status != NC_NOERR) {
         fprintf(stderr, "-E- Error finding nadir_view_time.\n");
         exit(EXIT_FAILURE);
     }  
     status = nc_inq_var_fill(groupid, varid, NULL, &scan_timeFillValue);
     check_err(status, __LINE__, __FILE__);
     status = nc_get_var_double(groupid, varid, scan_time);
     check_err(status, __LINE__, __FILE__);    
  
     // get start time
     size_t att_len;
     status = nc_inq_attlen(ncid_L1C, NC_GLOBAL, "time_coverage_start", &att_len);
     check_err(status, __LINE__, __FILE__);
  
     // allocate required space before retrieving values 
     char* time_str = (char *) malloc(att_len + 1); // + 1 for trailing null 
  
     // get attribute values 
     status = nc_get_att_text(ncid_L1C, NC_GLOBAL, "time_coverage_start", time_str);
     check_err(status, __LINE__, __FILE__);
     time_str[att_len] = '\0';
  
     double start_time = isodate2unix(time_str);
     int16_t syear, smon, sday;
     double secs;
     unix2ymds(start_time, &syear, &smon, &sday, &secs);
     file_start_day = ymds2unix(syear, smon, sday, 0.0);
  
     free(time_str);
  
     for(int i=0; i<num_scans; i++) {
         if(scan_time[i] == scan_timeFillValue)
             scan_time[i] = BAD_FLT;
     }
     
     // Setup geofile pointers
     status = nc_inq_grp_ncid(ncid_L1C, "geolocation_data", &geolocationGrp);
     check_err(status, __LINE__, __FILE__);
     status = nc_inq_varid(geolocationGrp, "longitude", &lonId);
     check_err(status, __LINE__, __FILE__);
     status = nc_inq_var_fill(geolocationGrp, lonId, NULL, &lonFillValue);
     check_err(status, __LINE__, __FILE__);
     status = nc_inq_varid(geolocationGrp, "latitude", &latId);
     check_err(status, __LINE__, __FILE__);
     status = nc_inq_var_fill(geolocationGrp, latId, NULL, &latFillValue);
     check_err(status, __LINE__, __FILE__);
  
     file->sd_id = ncid_L1C;
     file->nbands = num_bands;
     file->npix = num_pixels;
     file->nscan = num_scans;
     file->ndets = 1;
     file->terrain_corrected = 1; // presumed.
     strcpy(file->spatialResolution, "5.2km");
  
     if (want_verbose)
         printf("file->nbands = %d\n", (int) file->nbands);
  
     return (LIFE_IS_GOOD);
 }
  
  
 int readl1_l1c(filehandle *file, int32_t line, l1str *l1rec) {
  
     int status;
     size_t start[] = { 0, 0, 0 };
     size_t count[] = { 1, 1, 1 };
  
     for (int ip = 0; ip < num_pixels; ip++) {
         l1rec->pixnum[ip] = ip;
     }
  
     l1rec->npix = file->npix;
     if(scan_time[line] == BAD_FLT) {
         l1rec->scantime = BAD_FLT;
         l1rec->fsol = BAD_FLT;
     } else {
         l1rec->scantime = file_start_day + scan_time[line];
  
         int16_t syear, sday;
         double secs;
         unix2yds(l1rec->scantime, &syear, &sday, &secs);
  
         int32_t yr = syear;
         int32_t dy = sday;
         int32_t msec = (int32_t) (secs * 1000.0);
         double esdist = esdist_(&yr, &dy, &msec);
  
         l1rec->fsol = pow(1.0 / esdist, 2);
     }
  
     start[0] = line;
     start[1] = 0;
     start[2] = 0;
     count[0] = 1;
     count[1] = num_pixels;               // 1 line at a time
     count[2] = 1;
     status = nc_get_vara_float(geolocationGrp, latId, start, count, l1rec->lat);
     check_err(status, __LINE__, __FILE__);
     status = nc_get_vara_float(geolocationGrp, lonId, start, count, l1rec->lon);
     check_err(status, __LINE__, __FILE__);
  
     for(int i=0; i<num_pixels; i++) {
         if(l1rec->lat[i] == latFillValue)
             l1rec->lat[i] = BAD_FLT;
         if(l1rec->lon[i] == lonFillValue)
             l1rec->lon[i] = BAD_FLT;
  
         // set solz to 0 so all pixels are daytime
         l1rec->solz[i] = 0.0;
  
     }
     
     return (LIFE_IS_GOOD);
 }
  
  
 int closel1_l1c(filehandle *file) {
     int status;
  
     printf("Closing L1C file\n");
     status = nc_close(file->sd_id);
     check_err(status, __LINE__, __FILE__);
  
     // Free memory
     // From openl1_oci
     if (tmpShort) free(tmpShort);
     if (scan_time) free(scan_time);
  
     return (LIFE_IS_GOOD);
 }
  
  
  
  
  

l1mapgen.stderr

stderr

Definition: l1mapgen.py:204

status

int status

Definition: l1_czcs_hdf.c:32

check_err

void check_err(const int stat, const int line, const char *file)

Definition: nc4utils.c:35

NULL

#define NULL

Definition: decode_rs.h:63

readl1_l1c

int readl1_l1c(filehandle *file, int32_t line, l1str *l1rec)

Definition: l1_l1c.c:172

l1rec

read l1rec

Definition: HOWTO_Add_a_sensor.txt:72

unix2ymds

void unix2ymds(double usec, int16_t *year, int16_t *mon, int16_t *day, double *secs)

Definition: unix2ymds.c:8

nc4utils.h

msec

int32 * msec

Definition: l1_czcs_hdf.c:31

esdist_

double esdist_(int32_t *year, int32_t *day, int32_t *msec)

syear

int syear

Definition: l1_czcs_hdf.c:15

file

no change in intended resolving MODur00064 Corrected handling of bad ephemeris attitude resolving resolving GSFcd00179 Corrected handling of fill values for[Sensor|Solar][Zenith|Azimuth] resolving MODxl01751 Changed to validate LUT version against a value retrieved from the resolving MODxl02056 Changed to calculate Solar Diffuser angles without adjustment for estimated post launch changes in the MODIS orientation relative to incidentally resolving defects MODxl01766 Also resolves MODxl01947 Changed to ignore fill values in SCI_ABNORM and SCI_STATE rather than treating them as resolving MODxl01780 Changed to use spacecraft ancillary data to recognise when the mirror encoder data is being set by side A or side B and to change calculations accordingly This removes the need for seperate LUTs for Side A and Side B data it makes the new LUTs incompatible with older versions of the and vice versa Also resolves MODxl01685 A more robust GRing algorithm is being which will create a non default GRing anytime there s even a single geolocated pixel in a granule Removed obsolete messages from seed file

Definition: HISTORY.txt:413

LIFE_IS_GOOD

#define LIFE_IS_GOOD

Definition: passthebuck.h:4

sday

int sday

Definition: l1_czcs_hdf.c:15

time_str

int time_str(short, short, int, char *)

Definition: time_str.c:3

want_verbose

int want_verbose