[Stoch] Stochastic Parametrisation

John Schaake jcschaake at comcast.net
Sat Feb 25 14:13:52 MST 2012

Tim, Annan, et al:

I curious to know what different stochastic parameterizations assume about
the spatial and temporal joint distribution structure of the stochastic
innovations -- and what is the rationale for the assumptions.



-----Original Message-----
From: stoch-bounces at mailman.ucar.edu [mailto:stoch-bounces at mailman.ucar.edu]
On Behalf Of James Annan
Sent: Friday, February 24, 2012 2:59 AM
To: stoch at mailman.ucar.edu; Tim Palmer
Subject: Re: [Stoch] Stochastic Parametrisation

Hi Tim and all,

Thanks for the interesting read. I'm surprised no-one has mentioned to you
before, but I believe that the GISS GCM uses a stochastic parameterisation,
and in fact has done so since the 1980s.

I still don't understand how you draw a link between stochastic
parameterisation (which certainly seems a good idea to me) and the need for
model diversity (which I *also* think is important). Any single model,
stochastic or otherwise, will surely not be able to represent uncertainty in
the equilibrium response to any steady external forcing, essentially due to
the law of large numbers.

I would also hazard a guess that in your Lorenz '96 example, you could get
better results by taking the average of different stochastic approaches
(compared to any single scheme) - certainly if you chose a weight


> Comments are welcome.
> Tim

James D Annan jdannan at jamstec.go.jp Tel: +81-45-778-5618 (Fax 5707) Senior
Scientist, Research Institute for Global Change, JAMSTEC Yokohama Institute
for Earth Sciences, 3173-25 Showamachi, Kanazawa-ku, Yokohama City,
Kanagawa, 236-0001 Japan http://www.jamstec.go.jp/frcgc/research/d5/jdannan/
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