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[IDV #YTE-634929]: Questions about Avalanches, Scales Color, and NAM vs GFS precipitation analysis.

This archive contains answers to questions sent to Unidata support through mid-2025. Note that the archive is no longer being updated. We provide the archive for reference; many of the answers presented here remain technically correct, even if somewhat outdated. For the most up-to-date information on the use of NSF Unidata software and data services, please consult the Software Documentation first.

  • Subject: [IDV #YTE-634929]: Questions about Avalanches, Scales Color, and NAM vs GFS precipitation analysis.
  • Date: Fri, 10 Apr 2009 16:34:23 -0600
Hi-

This is Don.

> The GRIB2 - TABLE 4.2-0-1, PARAMETERS FOR DISCIPLINE 0 CATEGORY 1
> (Meteorological products, moisture category) Section 0 , Octet 7 = 0,
> say you ca n to use indistinctively units for evaporation and potential
> evaporation:
> 
> http://www.nco.ncep.noaa.gov/pmb/docs/grib2/grib2_table4-2-0-1.shtml
> 
> 6
> Evaporation
> kg m-2
> EVP
> 
> 40
> Potential Evaporation
> kg m-2
> PEVAP
> 
> 41
> Potential Evaporation Rate
> W m-2
> PEVPR
> 
> How can I change the units in the Software IDV,    Wm/2 to Kg/m2?

The W/m2 is a rate of evaporation and is not convertable to the kg/m2
which would be evaporation (essentially mm).

There is no way to do the physical conversion from W/m2 to mm/s since
it implies a mass conversion from l to mm of water.

However, you could use the formula Miscellaneous->Change Unit to
change the unit.  For the name, you can put whatever you want.
For the unitSpec, put in mm/s.  This will not attempt to do the
conversion, but will instead replace the real unit with whatever
you put in.  After that, you could use the Change Unit on your
display to convert to mm/day or whatever compatible unit  you want.

Don Murray

Ticket Details
===================
Ticket ID: YTE-634929
Department: Support IDV
Priority: Normal
Status: Closed