Robb,
Attached is the grib record for the 6th hour for parameter 167 (TEMP). I
hope it helps.
-Pelin
-----Original Message-----
From: Robb Kambic [mailto:address@hidden]
Sent: Thursday, September 11, 2008 1:30 PM
To: Bali, Pelin
Cc: decoders
Subject: RE: Fw: decoders] Grib1 Indexer and GDS info (fwd)
Pelin,
attached is Grib1ExtractRawData.java class. Put it in the grib1 dir and
compile. it will extract the first record if not parm # is given or all
the records of a certain parm, ie
% java -Xmx256m ucar/grib/grib1/Grib1ExtractRawData RUC.grib1 >
RUC1rec.grib1
or
% java -Xmx256m ucar/grib/grib1/Grib1ExtractRawData RUC.grib1 7 >
RUCparm7.grib1
can you create a file either 1 record or one with a reasonable # of
parms so i can use it as a test case.
RObb...
On Wed, 10 Sep 2008, Bali, Pelin wrote:
Robb,
I can attach the original ecmwf grib file if you want me to do so. It
is about 35MB... When I zip it, it didn't make much difference. Please
let me know how you want to proceed.
If I read the dx and dy values by using readShort method in the
Grib1GridDefinitionSection.java this is how grid definition section
looks like in the grib index file:
GDSkey = 1015536804
grid_type = 0
grid_name = Latitude/Longitude Grid
grid_shape_code = 0
grid_shape = spherical
grid_radius_spherical_earth = 6367.47
Nx = 720
Ny = 171
La1 = 65.0
Lo1 = 180.0
ResCompFlag = 128
Winds = Relative
La2 = -20.0
Lo2 = 179.5
Dx = -3.071
Dy = -3.071
ScanningMode = 0
--------------------------------------------------------------------
GDSkey = 3838746175
grid_type = 0
grid_name = Latitude/Longitude Grid
grid_shape_code = 0
grid_shape = spherical
grid_radius_spherical_earth = 6367.47
Nx = 720
Ny = 171
La1 = 65.0
Lo1 = 180.0
ResCompFlag = 128
Winds = Relative
La2 = -20.0
Lo2 = 179.5
Dx = -3.071
Dy = -3.071
ScanningMode = 0
--------------------------------------------------------------------
GDSkey = 1388487965
grid_type = 0
grid_name = Latitude/Longitude Grid
grid_shape_code = 0
grid_shape = spherical
grid_radius_spherical_earth = 6367.47
Nx = 360
Ny = 181
La1 = 90.0
Lo1 = 180.0
ResCompFlag = 128
Winds = Relative
La2 = -90.0
Lo2 = 179.0
Dx = -6.141
Dy = -6.141
ScanningMode = 0
If I read the same variables by using readInt2 method in the
Grib1GridDefinitionSection.java, I got the following values:
GDSkey = 1015536804
grid_type = 0
grid_name = Latitude/Longitude Grid
grid_shape_code = 0
grid_shape = spherical
grid_radius_spherical_earth = 6367.47
Nx = 720
Ny = 171
La1 = 65.0
Lo1 = 180.0
ResCompFlag = 128
Winds = Relative
La2 = -20.0
Lo2 = 179.5
Dx = 0.5
Dy = 0.5
ScanningMode = 0
--------------------------------------------------------------------
GDSkey = 3838746175
grid_type = 0
grid_name = Latitude/Longitude Grid
grid_shape_code = 0
grid_shape = spherical
grid_radius_spherical_earth = 6367.47
Nx = 720
Ny = 171
La1 = 65.0
Lo1 = 180.0
ResCompFlag = 128
Winds = Relative
La2 = -20.0
Lo2 = 179.5
Dx = 0.5
Dy = 0.5
ScanningMode = 0
--------------------------------------------------------------------
GDSkey = 1388487965
grid_type = 0
grid_name = Latitude/Longitude Grid
grid_shape_code = 0
grid_shape = spherical
grid_radius_spherical_earth = 6367.47
Nx = 360
Ny = 181
La1 = 90.0
Lo1 = 180.0
ResCompFlag = 128
Winds = Relative
La2 = -90.0
Lo2 = 179.0
Dx = 1.0
Dy = 1.0
ScanningMode = 0
Sincerely,
Pelin Bali
-----Original Message-----
From: Robb Kambic [mailto:address@hidden]
Sent: Tuesday, September 09, 2008 5:25 PM
To: Bali, Pelin
Cc: decoders
Subject: RE: Fw: decoders] Grib1 Indexer and GDS info (fwd)
On Thu, 28 Aug 2008, Bali, Pelin wrote:
Robb,
I've been registered to address@hidden and I was sending
my questions to 'address@hidden' all the time. I don't
know
how
it is being handled from there and how it falls into your spam. I
started to think that you were ignoring my messages. <:)
After sending this message, I made a little change in my code to read
Grib1GridDefinitionSection.params field to get HashMap of the
parameters. This helped me to get all the information I needed.
However,
in the grib1 index file, the Dx and Dy fields of the grid definition
section was still displaying wrong numbers. My colleague and I
started looking into the Grib1GridDefinitionSection.java. In the
section where the information obtained from octets 24-25 (Dx) and
octets 26-27(Dy or np), they were being read as "short". We changed
them to read by using
GribNumbers.int2 method (please see the following code snippet). It
started spitting out the correct numbers.
Sincerely,
Pelin Bali.
Pelin,
Here's my findings so far, the only time readSHort returns a wrong
value is the missing value scenario. ie when byte 1 and 2 = 255.
readShort returns -0.0010 and GribNumbers.int2 return -9999. Is this
what you are seeing? If not could you make available a file that i can
test.
thanks,
robb...
case 202 :
// octets 18-20 (La2 - latitude of last grid point)
lat2 = GribNumbers.int3(raf) / 1000.0;
// octets 21-23 (Lo2 - longitude of last grid point)
lon2 = GribNumbers.int3(raf) / 1000.0;
// octets 24-25 (Dx - Longitudinal Direction Increment )
//------------------------------------------------------
// This is where we made the change.
//-------------------------------------------------------
//dx = raf.readShort() / 1000.0;
dx = GribNumbers.int2(raf) / 1000.0;
// octets 26-27 (Dy - Latitudinal Direction Increment )
// Np - parallels between a pole and the
equator
if (type == 4) {
// np = raf.readShort();
np = GribNumbers.int2(raf);
} else {
// dy = raf.readShort() / 1000.0;
dy = GribNumbers.int2(raf) / 1000.0;
}
//-----------------------------------------------------------
// End of our changes.
//
----------------------------------------------------------
// octet 28 (Scanning mode) See Table 8
scan = raf.read();
// octet 29-32 reserved
reserved = raf.readInt();
if (P_VorL != 255) {
if( NV == 0 || NV == 255 ) {
getPL(raf);
} else {
getPV(NV, raf);
}
}
break; // end Latitude/Longitude grids
-----Original Message-----
From: Robb Kambic [mailto:address@hidden]
Sent: Wednesday, August 27, 2008 3:20 PM
To: Bali, Pelin
Cc: decoders
Subject: Re: Fw: decoders] Grib1 Indexer and GDS info (fwd)
Bali,
your support msg has been sitting in my spam folder for months now, i
just clean it out so that;s the reason for delay. There is an online
support
on unidata's home page and it's more dependable.
I going to address your msg in a general manner until we get to the
same
level. The Grib decoder package was meant to only be a low level API,
the data resolution that you are looking for would be easier to use a
ToolsUI program the uses the Grib package. Actually i think you
should be able to do the refinement w/o doing any coding. The ToolsUI
program is located
at:
https://www.unidata.ucar.edu/software/netcdf-java/
It will read in the file and it has options to select areas of data,
the
documentation is a little scarce but intuitive. The is also NCML that
will let you manipulate the output files.
On the other hand:
The grib package provides a dump, indexer and getData program that
can be used as templates to get the info you were looking for. There
are javadocs on all these routines on the decoders page.
There is also a display package IDV that could do the data
processing.
Hope this helps.
RObb...
---------- Forwarded message ----------
Date: Tue, 5 Aug 2008 10:59:21 -0400
From: "Bali, Pelin" <address@hidden>
To: address@hidden
Subject: decoders] Grib1 Indexer and GDS info
I am using the Grib1Indexer to read the Grib file. I need to get the
information lat, long, and nxny (145 X 73) as indicated below. I
tried
to use Index.GdsRecord, however I wasn't successful. Although I
could get start points of lat and long, I wasn't able to get neither
resolution nor the end points of lat & long by using gdsRecord.
Could you please show me some that direction on how to get this
information?
Thanks in advance.
------------
rec 98:1554711:date 2008080400 TMP kpds5=11 kpds6=105 kpds7=2
levels=(0,2) grid=16 2 m above gnd 24hr fcst:
TMP=Temp. [K]
timerange 0 P1 24 P2 0 TimeU 1 nx 145 ny 73 GDS grid 0 num_in_ave
0
missing 0
center 1 subcenter 0 process 45 Table 1 scan: WE:SN winds(N/S)
latlon: lat -90.000000 to 90.000000 by 2.500000 nxny 10585
long 0.000000 to 360.000000 by 2.500000, (145 x 73) scan
64 mode 128 bdsgrid 1--
The following is how I use the grib indexer to get the grib data.
RandomAccessFile raf = new RandomAccessFile(filePath, "r");
Grib1Indexer indexer = new Grib1Indexer(); PrintStream ps = new
PrintStream(indexPath); indexer.writeFileIndex(raf, ps, false );
Index index = new Index();
boolean rc = index.open(indexPath);
ArrayList gribIndexRecords = index.getGribRecords();
ArrayList<GdsRecord> gdsRecords = index.getHorizCoordSys(); // //
Build a hashmap for the GDS keys.
//
java.util.HashMap gdsMap = new java.util.HashMap();
for (int a = 0; a < gdsRecords.size(); a++) {
GdsRecord gdsRecord = gdsRecords.get(a);
gdsMap.put(gdsRecord.gdsKey, gdsRecord); }
for (Iterator it = gribIndexRecords.iterator (); it.hasNext (); ) {
zz++;
GribRecord gribRecord = (GribRecord)it.next();
if (gribRecord != null) {
//
// Select only temperature.
//
if (gribRecord.paramNumber == 11 ) {
if (gribRecord.levelType1 == 105) {
if (gribRecord.levelValue1 == 2.0) {
if (gribRecord.forecastTime ==
24) {
Grib1Data grib1data = new Grib1Data(raf);
if (gdsMap.get(gribRecord.gdsKey) !=
null) {
GdsRecord gds =
(GdsRecord)gdsMap.get(gribRecord.gdsKey);
System.out.println("Dx: " + gds.dx);
System.out.println("Dy: " + gds.dy);
System.out.println("Grid Shape Code: " + gds.grid_shape_code);
System.out.println("Grid Type: " + gds.grid_type);
System.out.println("La1: " + gds.La1);
System.out.println("LaD: " + gds.LaD);
System.out.println("Latin1: " + gds.latin1);
System.out.println("Latin2: " + gds.latin2);
System.out.println("Lo1: " + gds.Lo1);
System.out.println("LoV: " + gds.LoV);
System.out.println("Major Axis Earth " + gds.major_axis_earth);
System.out.println("Minor Axis Earth " + gds.minor_axis_earth);
System.out.println("Nx: " + gds.nx);
System.out.println("Ny: " + gds.ny);
System.out.println("Radius Spherical Earth: " +
gds.radius_spherical_earth);
System.out.println("Resolution: " + gds.resolution);
System.out.println("Winds: " + gds.winds);
}
float[] arr =
grib1data.getData(gribRecord.offset1, gribRecord.decimalScale,
gribRecord.bmsExists);
} // hour 24
} // 2m
} //above ground
} // end of temperature
} // grib record is not null
} // end for
Sincerely,
Pelin Bali
WeatherPredict Consulting, Inc.
3200 Atlantic Avenue, Suite 114
Raleigh, NC 27604
Phone (Direct): 919-239-8833
Phone (Main) : 919-876-3633
Fax : 919-876-4469
"Imagination will often carry us to worlds that never were.
But without it we go nowhere." - Carl Sagan (Cosmos - 1980)
======================================================================
==
=======
Robb Kambic Unidata Program Center
Software Engineer III Univ. Corp for
Atmospheric
Research
address@hidden WWW:
http://www.unidata.ucar.edu/
======================================================================
==
=======
======================================================================
==
=======
Robb Kambic Unidata Program Center
Software Engineer III Univ. Corp for Atmospheric
Research
address@hidden WWW:
http://www.unidata.ucar.edu/
======================================================================
==
=======
========================================================================
=======
Robb Kambic Unidata Program Center
Software Engineer III Univ. Corp for Atmospheric
Research
address@hidden WWW:
http://www.unidata.ucar.edu/
========================================================================
=======
