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[McIDAS #EIJ-330346]: McIDAS GRID file problem

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  • Subject: [McIDAS #EIJ-330346]: McIDAS GRID file problem
  • Date: Sat, 21 Oct 2006 15:26:07 -0600
Hi Mark,

I have been looking at the GRID decoding on FreeBSD 4.10, and think that the 
problem
we are both seeing is being caused by the CWDI grid that is being decoded into
the RTGRIDS/MISC dataset.  The CWDI (Convective weather detection index) grid is
very large:

GRDLIST RTGRIDS/MISC.4 PAR=CWDI FORM=ALL
Dataset position 4      Directory Title= Misc. Grids for 21 OCT 2006
PAR  LEVEL      DAY          TIME     SRC  FHR  FDAY         FTIME    GRID  PRO
---- ---------- ------------ -------- ---- ---- ------------ -------- ----- ----
CWDI SFC        21 OCT 06294 20:55:00  AWC    0 21 OCT 06294 20:55:00     1 MERC
Total pts=1679940 Num rows= 918  Num columns=1830   received:  2006294 205953Z
Convective weather detection index, Level average with      0
GRIB ID numbers: Geographic =  255; PAR =202; Model ID =190; Level type =200
Units of gridded variable are x    Scale of variable is:   2
Mercator Projection
Min Lat=  20.02  Max Lat=  53.00  Min Lon=  60.00  Max Lon= 129.98
Latitude Increment= 0.0359  Longitude Increment= 0.0382
Number of grids listed = 1
GRDLIST - done

Given the size (918x1830; 1679940 points; 6719760 bytes) and the broadcast 
frequency
(every 5 minutes!), the output data file rapidly reaches a maximum size of 2 GB:

DMAP GRID5004
PERM      SIZE LAST CHANGED FILENAME DIRECTORY
---- --------- ------------ -------- ---------
-rw- 2151490512 Oct 21 15:16 GRID5004 /export/data/ldm/mcidas
2151490512 bytes in 1 files

At or slightly before this point, the pointer needed to locate the grid in the 
GRID
file exceeds the maximum size allowed.

I am currently testing a modification to NOGRIB.CFG (which is found in 
~mcidas/workdata)
to turn off decoding of this grid.  Here is the NOGRIB.CFG addition that I am 
testing:

# The line below prevents all grids with generating process ID=190
# and geographic ID=255 and parameter 202 (CWDI grid) from being decoded
190  |-1  | -1 | -1 | -1 | 255 | 255 | -1 | -1 | 202 | 202

After making the addition to the end of ~mcidas/workdata/NOGRIB.CFG, I stopped
and restarted the grib data monitor (DMGRID) as follows:

<as 'mcidas'>
cd ~mcidas/workdata
-- add three lines above to the end of NOGRIB.CFG on the system running XCD
decinfo.k SET DMGRID INACTIVE
-- run 'ps -aux | grep DM' until you see DMGRID disappear from the listing !!!!!
decinfo.k SET DMGRID ACTIVE

I will know if the the problem we are both seeing on FreeBSD 4.10 goes away
with this modification.

Before you make the change above, can you check the size of the GRID files
being created on your system using:

<still as 'mcidas'>
cd ~mcidas/workdata
dmap.k GRID

I will report back by Monday with my results...

Cheers,

Tom
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Ticket Details
===================
Ticket ID: EIJ-330346
Department: Support McIDAS
Priority: Normal
Status: Closed