Missing result value

[gvan]

Hello.

I'm trying to parse grib2 file with temperature from GFS model. You can download a file by the following link.

Your library returns me value 27855.9 value at location 50.0, 30.0. It's a wrong value, because this file contains temperature representation in Kelvin.

Using ecCodes package's grib_dump command line tool with JSON mode grib_dump -j gfs.t06z.pgrb2.0p25.f000 I got a right values as a result:

    {
      "key" : "values",
      "value" :
      [
        278.951, 279.211, 278.551, 278.631 
      ]
    }

Using grib_dump command with octet mode grib_dump -O gfs.t06z.pgrb2.0p25.f000 I got the following Section 5:

======================   SECTION_5 ( length=21, padding=0 )    ======================
1-4       section5Length = 21
5         numberOfSection = 5
6-9       numberOfValues = 4
10-11     dataRepresentationTemplateNumber = 0 [Grid point data - simple packing (grib2/tables/2/5.0.table) ]
12-15     referenceValue = 27855.1
16-17     binaryScaleFactor = 0
18-19     decimalScaleFactor = 2
20        bitsPerValue = 7
21        typeOfOriginalFieldValues = 0 [Floating point (grib2/tables/2/5.1.table) ]

From this output we can see that referenceValue is 27855.1, which is too big for Kelvin temperature representation. We have to divide it by 100.

On the other hand I have downloaded grib file from ICON-EU model with temperature data too. You can download file by the following link.

For this file your library returns right values.

Using grib_dump -O file command for this file I got the following Section 5:

======================   SECTION_5 ( length=21, padding=0 )    ======================
1-4       section5Length = 21
5         numberOfSection = 5
6-9       numberOfValues = 904689
10-11     dataRepresentationTemplateNumber = 0 [Grid point data - simple packing (grib2/tables/19/5.0.table) ]
12-15     referenceValue = 258.822
16-17     binaryScaleFactor = -10
18-19     decimalScaleFactor = 0
20        bitsPerValue = 16
21        typeOfOriginalFieldValues = 0 [Floating point (grib2/tables/19/5.1.table) ]

File contains referenceValue = 258.822.

Can you investigate this problem and try to fix value parsing for GFS model?