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19991213: gridded precipitation units

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  • Subject: 19991213: gridded precipitation units
  • Date: Tue, 14 Dec 1999 09:33:18 -0700
>From: address@hidden (Chris Hennon)
>Organization: .
>Keywords: 199912132032.NAA25182

>Steve -
>
>I'm having a problem displaying model 6-hr precipitation fields in units
>of inches.  I used the following for gfunc:
>
>sm5s(sm5s(quo(P06M;25.4)))
>
>I get a maximum value of 37.09, with a lot of values around 6+".  Pretty
>unrealistic for a 6-hour total of liquid precip.  When I run using a gfunc
>of:
>
>sm5s(sm5s(P06M))
>
>I get realistic precip values in mm.  But when I try:
>
>sm5s(sm5s(P06I))
>
>I get the same values as the first one above.  I tried the same thing in
>GARP, which used the first gfunc, and it displayed realistic precipitation
>in inches.  So I'm not sure whats going on here.
>
>Thanks in advance for any help.
>
>Chris
>
>
>

Chris,

A first thing to check is your "scale" when you convert the precip
units to inches. If you have scale=0, then no scaling will occur,
but if it is scale=999 or scale=, then gempak may be scaling
the quantities by a factor of 10 (eg scale=1) or more.

When you run the program, gempak will show you the scale value along
with the contour intervals selected for you to approve. See if scale is
something besides 0.

Steve CHiswell