Monday, June 02, 2008

The Interdecadal Pacific Oscillation a Binary climate phenomena.

As we have seen in the previous post, we can divide the climate and its related interpretations into two components.

A) The fluctuations within a persistent regime or state, and

B) The supercritical or inverse oscillations of persistent states that are described as positive or negative (hotter or cooler)

Here A is a subset of B, and we can find a trend within the state being positive or negative, but we cannot use a trendline between states as this has different stochastic attributes. This is a fundamental flaw with using moving mean anomalies with data between two states with inverse it tends to amplify a trend.

We see this illustrated with the PDO and IPD where both phenomena changed phase near the time of the Pacific “climatic shift” around 1976 and which apparently influenced global temperatures.

The Interdecadal Pacific Oscillation (IPO) is (almost) the Pacific-wide manifestation of the Pacific Decadal Oscillation of Mantua et al (1997), with as much variance in the Southern Hemisphere Pacific down to at least 55oS as in the Northern Hemisphere. The IPO is a multidecadal sea surface temperature (SST) pattern quite like that of ENSO, but differing in several ways. It shows a marked amount of symmetry about the equator. It was introduced by Power et al (1999) based on work by Folland et al (1999). Power et al showed that the IPO modulated ENSO climate teleconnections to Australia. The near equivalence of the PDO and IPO and some likely independent effects of the IPO relative to ENSO on the South Pacific Convergence Zone were shown by Folland et al (2002). The concept of the IPO has recently been used in South Pacific paleoclimatic studies by Linsley et al (2004) and has been related to tropical rainfall patterns by Meinke et al (in press). The latter also compared IPO influences to those of SST on purely decadal time scales. The physical nature of the IPO is under investigation; it is still not clear, despite the above studies, to what extent the IPO is really independent of ENSO red noise and especially of SST variations near a decadal time scale.

These global bifurcations are called ‘‘Shilnikov phenomenon” and are well described in mathematical literature.

In the presence of inversion symmetry, we note that a periodic orbit can always be classified as either asymmetric or symmetric, with asymmetric orbits always

occurring in pairs in which each member transforms into the other under the inversion operation, while symmetric orbits are unique.

In a (supercritical) Hopf bifurcation, the real parts of the eigenvalues of a fixed point increase through zero from negative to positive, causing the stationary point to lose stability and a stable periodic orbit to be created.(see previous post Andronov)

So as we see the return to a period of cooler climatic persistence will falsify a substantive number of predictions , and is why we can predict an increasing amount of negative “forecasts” by researchers to ‘hedge their positions”so to speak.


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