[gradsusr] Specialized Display Question

[Rowell, Mason D.]

Jeff,

Even if lev is set to some specific level, I can still take the vertical deriv above and below that level? FYI, NARR does not have potential temp, and I tried something like 'd TMPprs*(1000/lev)^(2/7)' but it didn't want to use this expression.

Mason
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From: gradsusr-bounces at gradsusr.org [gradsusr-bounces at gradsusr.org] on behalf of Jeff Duda [jeffduda319 at gmail.com]
Sent: Tuesday, November 22, 2011 8:41 PM
To: GrADS Users Forum
Subject: Re: [gradsusr] Specialized Display Question

Mason,
You can use the cdiff command in the z direction to display variables (unfortunately, you can't use it to define variables).  However, you can approximate the vertical derivative by copying the method that cdiff uses.  If you have geopotential height, then you have all you need to compute a vertical derivative with respect to height coordinates.  You can display the vertical derivative of theta by either of the following:

'd cdiff(theta,z)'
'd (theta(z+1)-theta(z-1)) / (hgtprs(z+1)-hgtprs(z-1))

If you want to just view the gradient on one pressure surface, set the level that surface, then enter the command.

Jeff

On Tue, Nov 22, 2011 at 7:54 PM, Rowell, Mason D. <Mason.D.Rowell-1 at ou.edu<mailto:Mason.D.Rowell-1 at ou.edu>> wrote:
All,

Is it possible to display the vertical derivative of some quantity (like say temp or potential temp) on a pressure surface? I know I have height in my NARR data, but it is specific to a pressure level (i.e. HGTprs). What I would need is the height just above the current pressure level and below it in order to get cdiff of say theta and z. I'm not sure how to set the dimensions to do this...I would be okay with just getting this quantity for display at some level height, it doesn't have to be on a pressure surface.

Mason
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--
Jeff Duda
Grad student - PhD, Meteorology
University of Oklahoma School of Meteorology - Center for Analysis and Prediction of Storms

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