Re: Petterssen frontogenesis

My suggestion would be interpolate your WRF grid to a rectilinear grid
via the ESMF regridding:

http://www.ncl.ucar.edu/Applications/ESMF.shtml
See example 5

Then use the center_finite_diff function to compute the quantities.

On 4/19/13 2:14 AM, Bogdan Antonescu wrote:
> 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
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>
>
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Received on Fri Apr 19 14:06:44 2013