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Re: ecmwf hybrid levels (fwd)
- Subject: Re: ecmwf hybrid levels (fwd)
- Date: Mon, 22 Jun 2009 16:50:13 -0600 (MDT)
Hiya,
I'm interested in the Grib header information in the ECMWF data files.
An octal dump shows a blank header, ie
Here's an od of a header from a file.
7 7 7 7 \0 \0 \0 \0
15674460 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0
15674500 G R I B
The 7 7 7 7 is the end of the previous grib record, then there are all
nulls to the word G R I B which is the begining of the Grib
message. I didn't see information in any of the grib headers. Also
Grib1Dump didn't find any header information.
I'm looking for hybrid information in a Grib header.
Thanks,
Robb...
--------------------------------------------------------------------
Header : GRIB1
Discipline : 0 Meteorological Products
GRIB Edition : 1
GRIB length : 1558180
Originating Center : 98 European Center for Medium-Range
Weather Forecasts (RSMC)
Originating Sub-Center : 0 WMO Secretariat
Product Definition : 0 Forecast/Uninitialized Analysis/Image
Product
Parameter Category : -1 Meteorological Parameters
Parameter Name : 133 Q Specific_humidity
Parameter Units : kg kg-1
Reference Time : 2008-09-07T00:00:00Z
Time Units : hour
Time Range Indicator : product valid at RT + P1
Time 1 (P1) : 0
Time 2 (P2) : 0
Generating Process Type : 132 Unknown
Level Type : 109 hybrid level
Level Value 1 : 26.0
Level Value 2 : 0.0
GDS Exists : true
BMS Exists : false
Number of data points : 1038240
Grid Name : Latitude/Longitude Grid
Grid Shape: 0 spherical
Spherical earth radius: 6367.47
testdata/grid/grib/grib2/ecmwf/
ECMWF.2008.09.07.T00Z.uad_HGrbF00.A08334081908
is described here apparently:
http://www.ecmwf.int/products/data/technical/model_levels/model_def_91.html
and according to this:
http://www.ecmwf.int/research/ifsdocs/DYNAMICS/Chap2_Discretization4.html#961180
"The values of the and for all are stored in the GRIB header"
should be:
The values of a and b for all are stored in the GRIB header"
John,
Here's an od of a header from the above file.
7 7 7 7 \0 \0 \0 \0
15674460 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0 \0
15674500 G R I B
The 7 7 7 7 is the end of the previous grib record, then there are all
nulls to the word G R I B which is the begining of the Grib message. I
didn't see information in any of the grib headers. Also Grib1Dump didn't find
any header information. If they are referring to the above file name
ECMWF.2008.09.07.T00Z.uad_HGrbF00.A08334081908
I looked for product ID information and I found the similar information to
the NCEP information using header patterns
TTAAii CCCC YYGGgg Product Area
HHAA50 ECMF YYHH00 500 hPa geopotential height analysis (NH)
What header information are referring too and where is the documentation?
yes, thats the question. is it in section 2? can you contact ecmwf to find out?