David B. Benson wrote:
> From
> http://www.amath.washington.edu/people/faculty/tung/publications.html
>
> K.K. Tung, J. Zhou and C.D.Camp; 2008: "Constraining Model Transient
> Climate Response using Independent Observations of Solar-Cycle Forcing
> and Response" Geophys. Research Lett., 35, L17707,doi:
> 10.1029/2008GL034240.
>
> I don't see anything actually wrong, but I'm suspicious of such large
> values. Comments about what might have gone wrong, if anything, will
> be appreciated.
It's a bit misleading of them to claim the solar signal is confirmed by
multiple data sets, when in fact these are all pretty much the same
data, reanalysed in slightly different ways. I don't see any big howler
in their analysis but I am not convinced by the uncertainty estimates.
Actually, this may rise to the level of a significant error, since the
uncertainty bounds on k in their fig 2 are barely consistent (first two
subplots) even though the underlying data are almost the same! Thus, I
suspect their uncertainties are substantially underestimated. They also
admit in the text that their uncertainty estimates depend on the details
of the analysis but "will not be discussed further here". The lower
limit for k that they use in further analysis is actually the central
estimate from 3 of their 4 data sets. Including a reasonable amount of
uncertainty here would reconcile their estimate with others.
Their conversion from TCR to equilibrium sensitivity is also a bit
dubious - the 3/2 factor is just an approximation, and may be lower for
high TCR. That is, if the reason for high TCR is that the ocean mixing
is lower than the models simulate, this means we are closer to
equilibrium, it does not mean the equilibrium is higher. T&C haven't
really estimated equilibrium sensitivity with this method. However, it
may add some support for the work of Forest et al which claims that the
mixing in the GCM ocean models is overstated.
James
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