[gradsusr] Temperature Advection

[Mohsen Soltani]

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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