[gradsusr] Grads vertical derivative error with cdiff

[Aishwarya]

Hi,

Follow up on WRF vertical levels. Yes, WRF uses model levels. I used ARW
post to convert my model levels to pressure and height levels. So, now I
have geopotential and other parameters with height and pressure levels. I
was trying to plot them in grads because ARW post gives the output in .ctl
and .dat format.

I followed the suggestion 0.5*(geopt(z+1)-geopt(z-1)) and it worked out.
Although I'm not sure of my answer.

Thank you all,
Aishwarya.

On Tue, May 8, 2012 at 4:10 PM, Eric Altshuler <ela at cola.iges.org> wrote:

> As I recall, the person who started this thread is using WRF. The vertical
> coordinate in raw WRF history output is neither pressure nor height, but a
> hybrid coordinate. In grads, z levels would correspond to constant hybrid
> coordinate surfaces. Taking vertical derivatives with respect to this
> hybrid coordinate would not be very useful. The available postprocessing
> tools for WRF can interpolate fields onto pressure or height levels.
>
> Eric
>
> ----- Original Message -----
> From: "Arlindo da Silva" <dasilva at alum.mit.edu>
> To: "GrADS Users Forum" <gradsusr at gradsusr.org>
> Sent: Tuesday, May 8, 2012 2:21:41 PM
> Subject: Re: [gradsusr] Grads vertical derivative error with cdiff
>
>
> On Tue, May 8, 2012 at 1:42 PM, Andre Pattantyus <
> apattantyus2008 at my.fit.edu > wrote:
>
>
>
> you need to use geopotential on pressure surface you will never get an
> answer with z coordinate. This is a basic units concept people!
>
>
>
>
> In GrADS "z" is used to refer to the vertical dimension in index space,
> whatever that is: pressure or height.
>
>
> Arlindo
> --
> Arlindo da Silva
> dasilva at alum.mit.edu
>
> _______________________________________________
> gradsusr mailing list
> gradsusr at gradsusr.org
> http://gradsusr.org/mailman/listinfo/gradsusr
> _______________________________________________
> gradsusr mailing list
> gradsusr at gradsusr.org
> http://gradsusr.org/mailman/listinfo/gradsusr
>



-- 
*Aishwarya,
Graduate Research Assistant,
Atmospheric Sciences,
University of Arizona,Tucson.*
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://gradsusr.org/pipermail/gradsusr/attachments/20120508/c79ce1ee/attachment-0003.html