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/*
* (C) Copyright 2005- ECMWF.
*
* This software is licensed under the terms of the Apache Licence Version 2.0
* which can be obtained at http://www.apache.org/licenses/LICENSE-2.0.
*
* In applying this licence, ECMWF does not waive the privileges and immunities granted to it by
* virtue of its status as an intergovernmental organisation nor does it submit to any jurisdiction.
*/
/*
* C Implementation: bufr_read_temp
*
* Description: how to read temperature significant levels from TEMP BUFR messages.
*/
/*
* Please note that TEMP reports can be encoded in various ways in BUFR. Therefore the code
* below might not work directly for other types of TEMP messages than the one used in the
* example. It is advised to use bufr_dump to understand the structure of the messages.
*/
#include "eccodes.h"
static void free_memory(double* sigt_pres, double* sigt_geo, double* sigt_t, double* sigt_td)
{
free(sigt_pres);
free(sigt_geo);
free(sigt_t);
free(sigt_td);
}
int main(int argc, char* argv[])
{
FILE* in = NULL;
/* Message handle. Required in all the eccodes calls acting on a message.*/
codes_handle* h = NULL;
double *sigt_pres = NULL, *sigt_geo = NULL, *sigt_t = NULL;
double* sigt_td = NULL;
size_t sigt_len = 0, len = 0, i = 0;
int err = 0;
int cnt = 0;
const char* infile = "../../data/bufr/temp_101.bufr";
char key_name[128];
in = fopen(infile, "rb");
if (!in) {
fprintf(stderr, "Error: unable to open file %s\n", infile);
return 1;
}
/* Loop over the messages in the bufr file */
while ((h = codes_handle_new_from_file(NULL, in, PRODUCT_BUFR, &err)) != NULL || err != CODES_SUCCESS) {
if (h == NULL) {
fprintf(stderr, "Error: unable to create handle for message %d\n", cnt);
cnt++;
continue;
}
printf("message: %d\n", cnt);
/* We need to instruct ecCodes to expand the descriptors
i.e. unpack the data values */
CODES_CHECK(codes_set_long(h, "unpack", 1), 0);
/* In what follows we rely on the fact that for
* temperature significant levels the value of key
* verticalSoundingSignificance is 4 (see flag table 8001 for details).
*
* In our BUFR message verticalSoundingSignificance is always followed by
* geopotential, airTemperature, dewpointTemperature,
* windDirection, windSpeed and pressure.
* So in order to access any of these keys we need to use the
* condition: verticalSoundingSignificance=4.
*/
/* Get the number of the temperature significant levels.*/
/* We find out the number of temperature significant levels by
* counting how many pressure values we have on these levels.*/
sprintf(key_name, "/verticalSoundingSignificance=4/pressure");
CODES_CHECK(codes_get_size(h, key_name, &sigt_len), 0);
printf("Number of T significant levels: %lu\n", sigt_len);
/* Allocate memory for the values to be read. Each
* parameter must have the same number of values. */
sigt_pres = (double*)malloc(sigt_len * sizeof(double));
sigt_geo = (double*)malloc(sigt_len * sizeof(double));
sigt_t = (double*)malloc(sigt_len * sizeof(double));
sigt_td = (double*)malloc(sigt_len * sizeof(double));
/* Get pressure */
sprintf(key_name, "/verticalSoundingSignificance=4/pressure");
len = sigt_len;
CODES_CHECK(codes_get_double_array(h, key_name, sigt_pres, &len), 0);
/* Get geopotential */
sprintf(key_name, "/verticalSoundingSignificance=4/nonCoordinateGeopotential");
/* Check the size */
CODES_CHECK(codes_get_size(h, key_name, &len), 0);
if (len != sigt_len) {
fprintf(stderr, "Error: inconsistent number of geopotential values found!\n");
free_memory(sigt_pres, sigt_geo, sigt_t, sigt_td);
return 1;
}
/* Get the values */
CODES_CHECK(codes_get_double_array(h, key_name, sigt_geo, &len), 0);
/* Get temperature */
if (len != sigt_len) { /* Check the size */
fprintf(stderr, "Error: inconsistent number of temperature values found!\n");
free_memory(sigt_pres, sigt_geo, sigt_t, sigt_td);
return 1;
}
/* Get the values */
sprintf(key_name, "/verticalSoundingSignificance=4/airTemperature");
CODES_CHECK(codes_get_double_array(h, key_name, sigt_t, &len), 0);
/* Get dew point */
if (len != sigt_len) { /* Check the size */
fprintf(stderr, "Error: inconsistent number of dewpoint temperature values found!\n");
free_memory(sigt_pres, sigt_geo, sigt_t, sigt_td);
return 1;
}
/* Get the values */
sprintf(key_name, "/verticalSoundingSignificance=4/dewpointTemperature");
CODES_CHECK(codes_get_double_array(h, key_name, sigt_td, &len), 0);
/* Print the values */
printf("lev pres geo t td\n");
printf("-------------------------------\n");
for (i = 0; i < sigt_len; i++) {
printf("%3lu %6.0f %6.0f %.1f %.1f\n",
i + 1, sigt_pres[i], sigt_geo[i], sigt_t[i], sigt_td[i]);
}
/* Delete handle */
codes_handle_delete(h);
/* Release memory */
free_memory(sigt_pres, sigt_geo, sigt_t, sigt_td);
cnt++;
}
fclose(in);
return 0;
}
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