# RE: Eddy Height Computations

```Never mind!  I was mid-shower when how to apply this code dawned on me!
Thanks for the nudge!

Bruce

------------------------
Bruce W. Ford
http://www.EverythingDulcimer.com
Learn - Exchange - Improve

-----Original Message-----
From: Bruce or Jennifer Ford [mailto:fordville_bruce@yahoo.com]
Sent: Monday, April 01, 2002 11:20 PM
To: ferret_users@ferret.wrc.noaa.gov
Cc: Tom Murphree
Subject: Eddy Height Computations

Billy,
I understand the code below.  But how can I set the limits to be the
latitude of the current grid point only?  I looked for a reserved variable,
but I don't see it.

For my purposes, once I can designated the current latitude, it would look
like:

eddy_ht = hgt - hgt[y=current_lat:current_lat@ave]
(Height at the current grid point minus the globally averaged height of only
that same latitude.)

With each lat, the globally averaged height for the latitude will change.

If there's not a way to say "current latitude" in the code, could I set up a
loop?

I hope I'm accurately relaying what I'm trying to compute.  I welcome any
thoughts!

Bruce

-----Original Message-----
From: owner-ferret_users@ferret.wrc.noaa.gov
[mailto:owner-ferret_users@ferret.wrc.noaa.gov]On Behalf Of Billy
Kessler
Sent: Friday, March 29, 2002 5:07 PM
To: bruce@fordville.org
Cc: ferret_users@ferret.wrc.noaa.gov; tom_murphree@hotmail.com
Subject: Re: Eddy Height Computations

It should be:

eddy_ht = hgt - hgt[y=ys:yn@ave]

where ys and yn are the limits over which to take
the average. This specification is needed, even if
the whole region is intended, because otherwise a
statement such as:

plot eddy_ht[y=value]

would evaluate the entire expression (including the
averaging operation) at y=value. By including the
limits explicitly in the definition this is avoided.

Billy K

On Fri, 29 Mar 2002, Bruce W. Ford wrote:

> I'm attacking a new computation and I wish I was more
> familiar with the finer points of Ferret scripting.
> In time...in time.  Thank goodness for this forum!
>
> I want to calculate an eddy height value, that is
> subracting a latitude average from the value at each
> grid point.
>
> I'm thinking the computation code will look like:
> let eddy_hgt = hgt - hgt[h=@AVE]
>
> Has anyone performed these calculations?  Would this
> fit the bill?
>
> I appreciate any comments!  Thanks!
>
> Bruce
>
>
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