date: Thu, 28 May 2009 16:11:03 -0700
from: Darrell Kaufman <Darrell.Kaufman@nau.edu>
subject: Re: question 
to: "K.Briffa@uea.ac.uk" <K.Briffa@uea.ac.uk>

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Yes, I am beginning to think that the model has somewhat lower  
sensitivity than seen in the proxy data, as suggested by the reviewer.  
And, yes, the model data are based on 50-year means whereas the proxy  
data used 100-year means. We did this to keep the n the same for the  
two regressions (model = 1000 years; data = 2000 yr). I suppose I  
could use 50-yr means from the proxies and just randomly select half  
of the data for comparison. Before we go down that road, our NCAR co- 
authors are going to get back to me with more information on the model.

This just in from Dave:
I don't want to jump to the conclusion that the model is not sensitive  
enough. After all, for the T31 simulation (the resolution used for the  
mid-Holocene orbital run) t is ~3 degrees colder in the Arctic in the  
model's pre-Industrial climate compared to present day (1990); this is  
almost 3X the global average change. The Arctic is even colder when  
increasing the resolution to T42 (more realistic sea ice). It is  
possible that orbital forcing using T42 resolution would have higher  
sensitivity - that is one caveat we could make.

Let me know if you have other suggestions.
Darrell


On May 28, 2009, at 3:45 PM, K.Briffa@uea.ac.uk wrote:

> Darrell
> I am intriqued about how the model can get the one very anomalous warm
> point that does likely influence the regression result for simulated  
> data
> against model insolation. Have you looked into this? It is likely
> fortuitous that the regressions in Fig 4 give the same slope,  
> because of
> this. Also , what would be the difference if insolation was  
> calculated in
> the same way for both a and b ? Am I right in remembering that they  
> were
> not in fact the same?
>
> Keith
>

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