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The bufr_filter processes sequentially all bufr messages contained in the input files and applies the rules to each one of them. Input messages can be written to the output by using the "write" statement. The write statement can be parameterised so that output is sent to multiple files depending on key values used in the output file name.
Header BUFR header information can be accessed witout unpacking the data. This rules_file:
will result in the the follwing output:Code Block print "[bufrHeaderCentre] [bufrHeaderSubCentre] [masterTablesVersionNumber] [localTablesVersionNumber] [numberOfSubsets]";
Code Block > bufr_filter rules_file ../data/bufr/syno_multi.bufr 98 0 13 1 1 98 0 13 1 1 98 0 13 1 1
To print values from the data section the messages have to be unpacked. This rules_file:
will print out some data values from the specified SYNOP BUFR messages.Code Block set unpack=1; print "block=[blockNumber] station=[stationNumber] lat=[latitude] lon=[longitude] t2=[airTemperatureAt2M]";
Code Block > bufr_filter rules_file ../data/bufr/syno_multi.bufr block=1 station=1 lat=70.93 lon=-8.67 t2=274.5 block=1 station=3 lat=77 lon=15.5 t2=268.4 block=1 station=7 lat=78.92 lon=11.93 t2=268.5
The bufr_filter allows defining new keys with the transient keyword. We will further develop the previous example by creating a new key to combine the block number and the station number into the full WMO station id:
The result is:Code Block set unpack=1; transient statid=1000*blockNumber+stationNumber; print "statid=[statid] lat=[latitude] lon=[longitude] t2=[airTemperatureAt2M]";
Code Block > bufr_filter rules_file ../data/bufr/syno_multi.bufr statid=1001 lat=70.93 lon=-8.67 t2=274.5 statid=1003 lat=77 lon=15.5 t2=268.4 statid=1007 lat=78.92 lon=11.93 t2=268.5
To access the attributes belonging to the keys use the -> operator. The example below prints the attributes of key "pressure" from a SYNOP BUFR message.
The result is:Code Block print "pressure=[pressure] [pressure->units]"; print "pressure->code=[pressure->code!06d]"; print "pressure->scale=[pressure->scale]"; print "pressure->reference=[pressure->reference]"; print "pressure->width=[pressure->width]"; print "pressure->percentConfidence=[pressure->percentConfidence] [pressure->percentConfidence->units]"; print "pressure->percentConfidence->code=[pressure->percentConfidence->code!06d]"; print "pressure->percentConfidence->scale=[pressure->percentConfidence->scale]"; print "pressure->percentConfidence->reference=[pressure->percentConfidence->reference]"; print "pressure->percentConfidence->width=[pressure->percentConfidence->width]";
Code Block > bufr_filter rules_file ../data/bufr/syno_1.bufr pressure=100910 Pa pressure->code=010004 pressure->scale=-1 pressure->reference=0 pressure->width=14 pressure->percentConfidence=74 % pressure->percentConfidence->code=033007 pressure->percentConfidence->scale=0 pressure->percentConfidence->reference=0 pressure->percentConfidence->width=7
To access elements by rank (i.e. by their occurence in the message) use the # operator. The example below prints the 4th value of key "pressure" from a TEMP BUFR message.
The result is:Code Block set unpack=1; print "pressure=[pressure#4] [pressure#4->units]"; print "pressure=[pressure]";
Code Block > bufr_filter rules_file ../data/bufr/temp_101.bufr pressure=98500 Pa pressure=102000 101800 100000 98500 96400 92500 92100 89700 88100 86100 85000 84400 79400 79000 78300 77300 71900 70000 69400 65100 61200 53400 50000 43900 40000 39900 37800 31600 30000 27500 25000 21200 21000 20600 20400 20000 19300 18400 17000 16600 15100 15000 14600 14000 13400 13200 12900 11100 10800 10000 8960 7630 7000 6420 6190 5770 5320 5000 3970 3570 3190 3090 3000 2820 2630 2400 2340 2050 2000 1680 1530 1500 1380 1300 1210 31600