Friday, January 07, 2011

Spencer e-mail to Dessler on 1/7/11

Happy New Year Andy,

I've been catching up this week after having last week off for the holidays.

The evidence I presented you was NOT just the decorrelation of the data, as you I mentioned in my previous e-mail , it was TWO-fold: It is also the lagged relationship, with radiative flux changes preceding the temperature response, then the temperature changes either simultaneous with (os as we will see with ENSO, preceding) the radiative feedback response. The phase space plots we published are one way of revealing the lagged relationship.

Without taking this time lag into account, you will get correlations -- and thus regression slopes-- close to you do, even in the climate model matter what the feedbacks are. We demonstrated this in Spencer & Braswell (2010).

Now, let's look at the oceans, since you want to emphasize the signature of ENSO during the period of record....

By far the most precise measurements of global SST variations come from AMSR-E on NASA's Aqua satellite and, as you know, a CERES radiation budget instrument also flies on that satellite. I did a calculation with these data somewhat similar to the one you did.

Attached find a plot somewhat analogous to yours, but from Aqua SST versus radiative flux....As you can see, the radiative feedback response occurring AFTER the temperature changes suggest strongly negative feedback. Also shown in the same plot AR4 climate model results from their 20th Century runs on the same plot.

The peak correlation of the satellite data in the plot was 0.68, at 11 months lag. At zero lag, the correlation is only 0.27. (What was the correlation of the data you showed in Fig. 2 of your Science paper? I did not see one listed.)

Clearly, there are cause-effect things going on here that cannot be revealed in plots like your Fig. 2, unless these time lags are taken into account.

As a result of our discussion, I've decided that we should do another publication, focusing on the lag relationships seen in the Aqua data and what they might mean for feedback and climate model validation.


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