[Met_help] pcp_combine, trouble reading GRIB

[John Halley Gotway]

Matt,

I'm guessing it's a big vs. little endian issue.  The LINUX machines on which we developed MET are all little endian.  But then when we got MET up and running on bluevista and bluefire (NCAR's IBM's), 
we had to add support for big endian.  We found that MET would compile on the IBM with the wrong endian selected - but we'd get garbage data from the GRIB files, which is exactly what you're seeing.

In the top-level MET Makefile for an IBM, the architecture flags are set as follows:
ARCH_FLAGS = -DIBM -DBIGENDIAN

So just make sure that that's how it's set in your top-level Makefile.  And I assume your IBM is big endian.

The ARCH_FLAGS variable is used in the sub-makes but only in 3 of the libraries (vx_grib_classes, vx_util, and vx_wrfdata).  On our IBMs, passing it to the compiler in those places was sufficient. 
However, it's possible that we'd need to pass it in additional Makefiles on your IBM for some reason.

Sorry for the issues you're encountering, but support for IBMs is new for METv1.1.  So I'm not surprised that there are hiccups.  Hopefully we can straighten them out.

John

matthew.pyle at noaa.gov wrote:
> Hi,
> 
> I got everything to compile okay, but am not having success with the 
> pcp_combine tests.  I get garbagey (1e+30) kinds of values for the 
> precipitation totals in the resulting netCDF files, and the bad 
> information appears to be coming from the GRIB.  Turning up the 
> verbosity, I see some proper PDS/GDS information from the GRIB, along 
> with some bad values.   Any ideas why some of the GRIB information 
> appears to be read okay, while other parts are not?  I'm doing this work 
> on an IBM.  A few diagnostic snippets are below.
> 
> Thanks,
> 
> Matt
> 
> 
>   lat1:       12190
>   lon1:       8522067  <--- should be -133459 (or 226541 E)
>   res_flag:   8
>   lov:        8483608 <--- should be -95000 (or 265000 E)
>   dx:         40635
>   dy:         40635
>   pc_flag:    0
>   scan_flag:  64
>   latin1:     25000
>   latin2:     25000
>   lat_sp:     0
>   lon_sp:     0
> 
> ===================================================
> 
> Grib Record:
> 
>   gds_flag:            1
>   bms_flag:            1
>   nx:                  185
>   ny:                  129
>   m_value:                0.00100
>   b_value:                  -NaNQ
>   r_value:                  -NaNQ
>   d_value:             3
>   e_value:             0
>   issue:               1123372800
>   lead:                32400
>   word_size:           14
>   record_lseek_offset: 8257958
>   data_lseek_offset:   8261037
>   mask:                16383
> 
> ===================================================
> Grib Record Index = 560
> Initialization time = 1123372800
> Valid time = 1123416000
> Accumulation time = 10800
> Grib Record (min, max) = (100000002004087734272.00000, 
> -100000002004087734272.00000)
> 
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