[GEMPAK #XRW-645117]: question/problem with GDVINT

> I am trying to use the GDVINT program on the RUC236 model data. The
> model has data at every 50mb levels and I am wanting to interpolate it
> to every 25 mb levels. It seems to be doing ok except for one thing. In
> the model there is a RELH grid at every 50 mb intervals (ie, 950mb;
> 900mb; 850mb; etc). When I run GDVINT it is not creating a RELH grid at
> the 25 mb interval levels. (ie, 975mb; 925mb; 875 mb, etc).  Actually I
> am seeing  a SPFH grid instead. Why is this and how can I change it to
> get the RELH grid?  I need the RELH grids for some other scripts I am
> running.  Thanks.
> 
> Kevin Polston
> Senior Instructor, NWSTC
> Kansas City MO 64152
> 
> 816-880-9314 ext 273
> 
> 

SPFH is the specific humidty. GEMPAK will automatically convert from
specific humidity grids to mixing ratio (eg mixr = spfh / (1 - spfh)).

Of course, you can get RELH from MIXR/MIXS * 100.0.

Specific humidity is interpolated as the moisture quantity, since the mass
can be interpolated independently of other quantities. Interpolating RELH 
would involve both temperature as well as water vapor, and therefore
not a reliable method.

Steve Chiswell
Unidata User Support



Ticket Details
===================
Ticket ID: XRW-645117
Department: Support GEMPAK
Priority: Normal
Status: Open