Re: Petterssen frontogenesis

Hi,

Thank you very much for your help. I have managed to calculate
Petterssen frontogenesis from GFS using "gradsf" and "advect_gradient"
from shea_util. Now I want to calculate Miller frontogenesis using WRF
output data. Basically I want to calculate these therms: dtheta/dx,
dtheta/dy, du/dx, du/dy, dv/dx, dv/dy. I am not sure how to do this, and
I don't think that I can use the spherical harmonic functions with WRF.

Thank you very much,
Bogdan

On 10/12/12 16:43, Dennis Shea wrote:
> Forgot to mention ....
>
> If you do use the spherical harmonic functions, they do
> require that the grids be ordered south->north.
>
> Likely, the GFS are N->S. Use NCL syntax to reorder
>
> if x(time,lev,lat,lon)
>
> x = x(:,:,::-1,:)
>
> if x(time,lat,lon)
>
> x = x(:,::-1,:)
>
> printVarSummary(x)
>
> On 12/10/12 8:56 AM, Dennis Shea wrote:
>> There is no builtin Petterssen frontogenesis equation.
>>
>> However, the GFS is a global grid and the spherical harmonic
>> functions could be used to accurately calculate some of the
>> various terms.
>>
>> gradient terms: du/dx, dv/dx, dy/dy, du/dy
>> http://www.ncl.ucar.edu/Document/Functions/Built-in/gradsf.shtml
>>
>> There is an **unsupported** function in shea_util.ncl
>>
>> function advect_gradient (u:numeric, v:numeric, x:numeric \
>> ,gridType[1]:integer, con[1]:numeric \
>> ,long_name:string, units:string,
>> iopt[1]:integer)
>> ;
>> ; linear advection of a scalar quantity: UV.GRADIENT(X)
>> ; : U*(dX/dlon) + V*(dX/dlat)
>> ======
>> The documentation is embedded in the library. You can read vis:
>>
>> %> less $NCARG_ROOT/lib/ncarg/nclscripts/csm/shea_util.ncl
>>
>> search for 'advect_gradient'
>>
>> Don't know about the calculation of the angles.
>>
>>
>> On 12/9/12 3:56 AM, Adrian Antonescu wrote:
>>> Hi,
>>>
>>> Does anyone have a NCL script to calculate Petterssen frontogenesis?
>>> I am trying to calculate Petterssen frontogenesis using the GFS 0.5
>>> degrees data.
>>>
>>> Thank you so much.
>>>
>>> Bogdan Antonescu
>>>
>>> The University of Manchester
>>> Simon Building, Oxford Road
>>> Manchester, M13 9PL, United Kingdom
>>> Room 3.16, Simon Building
>>> +44 (0)161 306 3911
>>> _______________________________________________
>>> ncl-talk mailing list
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-- 
Bogdan Antonescu
Postdoctoral Research Associate
Centre for Atmospheric Science
School of Earth, Atmospheric and Environmental Sciences
The University of Manchester
Simon Building, Oxford Road
Manchester, M13 9PL, United Kingdom
Room 3.16, Simon Building
+44 (0)161 306 3911
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