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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.
#
# Python implementation: bufr_read_scatterometer
#
# Description: How to read data for a given beam from scatterometer BUFR
# messages.
#
# Please note that scatterometer data can be encoded in various ways in BUFR.
# Therefore the code below might not work directly for other types of messages
# than the one used in the example. It is advised to use bufr_dump first to
# understand the structure of these messages.
#
import sys
import traceback
from eccodes import *
INPUT = "../../data/bufr/asca_139.bufr"
VERBOSE = 1 # verbose error reporting
def example():
# open bufr file
f = open(INPUT, "rb")
cnt = 0
# loop for the messages in the file
while 1:
# get handle for message
bufr = codes_bufr_new_from_file(f)
if bufr 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(bufr, "unpack", 1)
# The BUFR file contains a single message with 2016 subsets in a
# compressed form. It means each subset has exactly the same structure:
# they store one location with several beams and one backscatter value
# in each beam.
#
# To print the backScatter values for beamIdentifier=2 from all the
# subsets we will simply access the key by condition (see below)
# Get the total number of subsets.
numObs = codes_get(bufr, "numberOfSubsets")
print(" Number of values: %ld" % numObs)
# Get latitude (for all the subsets)
lat = codes_get_array(bufr, "latitude")
# Get longitude (for all the subsets)
lon = codes_get_array(bufr, "longitude")
# Get backScatter for beam two. We use an access by condition for this
# key (for all the subsets).
bscat = codes_get_array(bufr, "/beamIdentifier=2/backscatter")
# Check that all arrays are same size
if len(lat) != numObs or len(lon) != numObs or len(bscat) != numObs:
print("inconsistent array dimension")
return 1
# Print the values
print("pixel lat lon backscatter")
print("-------------------------------")
for i in range(numObs):
print("%3d %.2f %.2f %.2f" % (i + 1, lat[i], lon[i], bscat[i]))
cnt += 1
# Release handle
codes_release(bufr)
# Close the file
f.close()
def main():
try:
example()
except CodesInternalError as err:
if VERBOSE:
traceback.print_exc(file=sys.stderr)
else:
sys.stderr.write(err.msg + "\n")
return 1
if __name__ == "__main__":
sys.exit(main())
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