[MITgcm-support] documentation for pkg/smooth

[Matthew Mazloff]

Hello

Just to chime in again :o)

It is, mathematically, the full diffusion, because we apply sqrt on the gradients and the sqrt on the ctrls. So for a full optimization cycle it really does essentially become full diffusion on the ctrl fields.

Matt





On Apr 6, 2015, at 5:36 PM, gael forget <gforget at mit.edu> wrote:

> Hi Dimitris,
> 
>> Dear MITgcmers,
>> is any documentation for pkg/smooth available?
> Unfortunately this is still missing from mitgcm documentation. 
> I hope to take time to add to MITgcm documentation regarding 
> this package (as well as ecco,ctrl, and profiles …) this spring.
> 
>> In particular, I am trying to understand how pkg/smooth parameters relate
>> the (2 k_1 T)^0.5 length scale discussed in the Weaver and Courtier paper:
>> http://mitgcm.org/~gforget/pdfs/weavercourtier01.pdf
> The parameters as set in data.smooth follow WC01’s notations 
> (if I recall correctly) specify the spatial correlation modeling 
> for use with pkg/ctrl & autodiff. Is this what you are trying to do? 
> 
>> Or more precisely, what is the half-power bandwidth
>> of a filter based on following parameters:
>> &SMOOTH_NML
>> smooth2Dnbt(1)=5000
>> smooth2D_Lx0(1)=100000.
>> smooth2D_Ly0(1)=100000.
>> smooth2Dtype(1)=1
>> smooth2Dsize(1)=0
>> smooth2Dfilter(1)=0
> In the case of the WC01 correlation modeling (if I recall correctly) 
> it is only the squared root of the diffusion operator that is applied.
> 
> If the matter is simply to smooth out a field up to a specified scale, 
> things are somewhat different. You want to use smooth_hetero2d.F 
> or smooth_basic2D.F and will find examples in pkg/ecco.
> 
> I hope this helps,
> Gael
> 
>> Does above define a lowpass filter for scales greater than 100 km,
>> 200 km, 628 km, or some other value?
>> 
>> Thanks, Dimitris
>> 
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