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Friday, October 19, 2012

Weakly Damped Lost in the Noise

Natural internal oscillations appear to be weakly damped.  Since the forcings are not using the same dampening, that leads to fun "seeing" what is going on in the climate system.  To dig out some of the "signal" there are some simple ways that don't require a ton of work.

This chart is the HADCRUT4 detrended 30-30 or tropical data with 11yr moving average, 4 year moving average that is not labeled for some reason and the average of the two moving averages.  The 11 year averaging smooths the curve more than the 4 year moving average and the average of the two is not all that informative.  By subtracting the 4 year moving average from the 11 year moving average, you can highlight the differences and remove the trends.

This chart is the difference of the 11 and 4 year moving averages for the NH, Tropics and SH HADCRUT4 data.  We now have a signal envelop.  As you can see, the NH and SH do not respond the same to the forcing signal, likely the solar cycle variations.

By adding the Svalgaard TSI reconstruction you can see two points where solar is in phase with the internal oscillations and a box where the internal signal dramatically reduces.  The entry to the box, solar is 180 degrees out of phase with the internal signal and at the exit of the box, solar is nearly in phase with the internal signal.  This is likely due to the damening of the internal signal first being different between hemispheres and longer than the ~11 year solar cycle.

This chart is just a weakly damped sinewave.  When a solar cycle is in phase with the first peak, it would have the greatest impact, the second peak would have noticeable impact and the third peak may or may not be large enough to notice.  Since the solar cycle is only in phase every second to fifth oscillation, trying to isolate solar's true impact would be a major bitch.  Needless to say, assuming a 2 or 3 year lag without considering the internal dampening, would be pretty useless.

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