[gradsusr] Temperature Advection

[Mohsen Soltani]

Hello Eric,

Thank you very much for your nice suggestion. Yes, it would be much better,
if I plot it in K/day. But, where exactly I should put this (86400) in the
following function?

define dtx = cdiff(t,x) define dty = cdiff(t,y)define dx =
cdiff(lon,x)*3.1416/180 define dy = cdiff(lat,y)*3.1416/180display -1*(
(u*dtx)/(cos(lat*3.1416/180)*dx) + v*dty/dy )/6.37e6


Thank you!
Mohsen


--
some are weather-wise some are otherwise!
--
Best Wishes,
(Mr.) Mohsen Soltani
Climatology Grad Student (M.Sc.),
Faculty of Geography, University of Tehran, Tehran, Iran
Tel: (+98) 9119772934
e-mail: soltani.clima at gmail.com


On Fri, May 24, 2013 at 12:48 PM, Eric Altshuler <ela at cola.iges.org> wrote:

> Hi Mohsen,
>
> Your expressions seem to be correct. If temperature is in K and winds are
> in m/s, temperature advection will be in K/s. You might want to plot it in
> K/day (multiply by 86400) to get "nicer" values on the order of 1-10
> instead of those tiny (~1e-5) values.
>
> Eric
>
> ------------------------------
> *From: *"Mohsen Soltani" <soltani.clima at gmail.com>
> *To: *"GrADS Users Forum" <gradsusr at gradsusr.org>
> *Sent: *Friday, May 24, 2013 2:29:35 PM
> *Subject: *[gradsusr] Temperature Advection
>
>
> Dear Friends,
>
> I have produced "Temperature Advection" using cdiff function, which is
> available at "GrADS Documentation Index":
> http://www.iges.org/grads/gadoc/gadocindex.html
>
> The full command is like this:
> define dtx = cdiff(t,x)define dty = cdiff(t,y) define dx =
> cdiff(lon,x)*3.1416/180define dy = cdiff(lat,y)*3.1416/180 display -1*(
> (u*dtx)/(cos(lat*3.1416/180)*dx) + v*dty/dy )/6.37e6
> where,
> the variable t is temperature, u and v are the U and V components of the
> wind, respectively.
>
> In fact, I am working on an advective cooling event (frost) over Iran.
> The frost event was occurred as a result of an extra-ordinary extension of
> the Polar Vortex toward the lower latitudes.
> The attached are the outputs that I made, which the first one indicates
> the start of the frost event, and the second one shows the end of the event
> over the country. I have to say that, they are in a very good agreement
> with the synoptic charts as well as outputs from HYSPLIT trajectory model.
>
> Briefly speaking, is it really a temperature advection map? If so, do you
> know what the unit of the temp advection is?  And how it should be
> explained?
>
>
> Thank you!
> Mohsen
>
> --
> some are weather-wise some are otherwise!
> --
> Best Wishes,
> (Mr.) Mohsen Soltani
> Climatology Grad Student (M.Sc.),
> Faculty of Geography, University of Tehran, Tehran, Iran
> Tel: (+98) 9119772934
> e-mail: soltani.clima at gmail.com
>
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