eccodes/examples/python/bufr_read_temp.py

# Copyright 2005-2015 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.

#
# Python 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.
#

import traceback
import sys

from eccodes import *

INPUT = '../../data/bufr/temp_101.bufr'
VERBOSE = 1  # verbose error reporting


def example():

    # open bufr file
    f = open(INPUT)

    cnt = 0

    # loop for the messages in the file
    while 1:
        # get handle for message
        gid = codes_bufr_new_from_file(f)
        if gid is None:
            break

        print "message: %s" % cnt

        # we need to instruct ecCodes to expand all the descriptors
        # i.e. unpack the data values
        codes_set(gid, 'unpack', 1)

        # 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).

        # We also make use of the fact that in our BUFR message
        # verticalSoundingSignificance is always followed by geopotential,
        # airTemperature, dewpointTemperature,
        # windDirection, windSpeed and pressure.

        # 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.

        numSigT = codes_get_size(gid, "/verticalSoundingSignificance=4/pressure")
        print '  Number of temperature significant levels %ld' % (numSigT)

        # Get pressure
        sigt_pres = codes_get_array(gid, "/verticalSoundingSignificance=4/pressure")

        # Get gepotential
        sigt_geo = codes_get_array(gid, "/verticalSoundingSignificance=4/geopotential")

        # Get temperature
        sigt_t = codes_get_array(gid, "/verticalSoundingSignificance=4/airTemperature")

        # Get dew point
        sigt_td = codes_get_array(gid, "/verticalSoundingSignificance=4/dewpointTemperature")

        # Check that all arrays are same size
        if len(sigt_pres) != numSigT or len(sigt_geo) != numSigT or len(sigt_t) != numSigT or len(sigt_td) != numSigT:
            print 'inconsistent array dimension'
            return 1

        # Print the values
        print "lev  pres    geo    t    td"
        print "-------------------------------"

        for i in xrange(numSigT):
            print "%3d %6.0f %6.0f %.1f %.1f" % (i + 1, sigt_pres[i], sigt_geo[i], sigt_t[i], sigt_td[i])

        cnt += 1

        # delete handle
        codes_release(gid)

    # close the file
    f.close()


def main():
    try:
        example()
    except CodesInternalError, err:
        if VERBOSE:
            traceback.print_exc(file=sys.stderr)
        else:
            print >>sys.stderr, err.msg

        return 1

if __name__ == "__main__":
    sys.exit(main())