20020212: Isallobaric wind

>From: Mohan Ramamurthy <address@hidden>
>Organization: UCAR/Unidata
>Keywords: 200202121635.g1CGZvx09773

>
>>Chiz,
>
>A quick questions: How do I plot the isallobaric wind?  That is, what is 
>the argument to ISAL?
>Is it the isallobaric field or something else?
>
>Thanks,
>
>Mohan
>
>
>----------------------------------------------------------------------------
>Dr. Mohan Ramamurthy                                   e-mail: address@hidden
> c.edu
>Associate Professor                                    Ph:  (217) 333-8650
>Department of Atmospheric Sciences                     Fax: (217) 244-4393
>University of Illinois at Urbana-Champaign
>105 S. Gregory Street
>Urbana, IL 61801-3070
>

Mohan,

On a pressure surface, it is generally ISAL(HGHT). Or, simply ISAL.

The function will compute the Geostropic wind from the scalar to
ISAL(S), so most often you would use HGHT to compute the
geostrophic wind. ISAL is also one of those predefined variables
that will try to compute as just ISAL without any arguments
(like WND, GEO, AGE, etc). The isallobaric wind requires a time
difference, so gdattim is 2 times time1:time2. As an exaple using 
GDPLOT2:

GDFILE  = ETA
GDATTIM = f000:f024
GVCORD  = pres
GLEVEL  = 700
TYPE    = a
WIND    = ak6
etc...

Steve Chiswell