A new paper in Geophysical Research Letters was brought to my attention by Dr. Leif Svalgaard.
Tropical origins of North and South Pacific decadal variability by Jeremy D. Shakun and Jeffrey Shaman makes some very interesting findings suggesting that both the northern and southern Pacific Ocean has evidence of the Pacific Decadal Variation PDV being driven by ENSO variations. They produced a model, which when run correlates reasonably well with observations.
Abstract:
The origin of the Pacific Decadal Oscillation (PDO), the leading mode of sea surface temperature variability for the North Pacific, is a matter of considerable debate. One paradigm views the PDO as an independent mode centered in the North Pacific, while another regards it as a largely reddened response to El Nin˜o-Southern Oscillation (ENSO) forcing from the tropics. We calculate the Southern Hemisphere equivalent of the PDO index based on the leading mode of sea surface temperature variability for the South Pacific and find that it adequately explains the spatial structure of the PDO in the North Pacific. A first-order autoregressive model forced by ENSO is used to reproduce the observed PDO indices in the North and South Pacific. These results highlight the strong similarity in Pacific decadal variability on either side of the equator and suggest it may best be viewed as a reddened response to ENSO.
They write about the graph above:
…we model PDV as a first-order autoregressive process driven by ENSO as done by Newman et al. [2003]. This AR-1 model is applied to the North and South Pacific separately.
The modeled PDO index at year n is a function of the modeled PDO index at n – 1 and the observed ENSO index (Nino 3.4) at n. These annually-averaged indices are centered on boreal winter (Jul–Jun) for the North Pacific and austral winter (Jan–Dec) for the South Pacific. Per Newman et al. [2003], the coefficients β and α are parameters derived, respectively, by regression of the PDO index on the ENSO index, then autoregression of the residual time series with a lag of one year. h is an uncorrelated noise term not used in our analysis but shown for completeness. a and b are 0.51 and 0.56 for North Pacific PC1 and 0.62 and 0.71 for South Pacific PC1. While Newman et al. [2003] found this simple model did a remarkable job reproducing the observed 20th century PDO index in the North Pacific (r = 0.63 in our study), it yields an even stronger fit to our Southern Hemisphere PDO index (r = 0.71) (Figure 4).
The greater success of the model in the South Pacific may be a function of its larger α and β terms, which indicate that the persistence of SST anomalies and ENSO forcing are more important. The stronger ENSO signal in the South Pacific may derive from the equatorial asymmetry of ENSO SST anomalies in the eastern tropical Pacific, which extend considerably farther to the south than to the north. One implication of this finding is that the South Pacific may be a better place to develop paleo-ENSO records as it appears to contain a ‘cleaner’ ENSO signal.
Conclusion
Deriving a Southern Hemisphere equivalent of the PDO index shows that the spatial signature of the PDO can be well explained by the leading mode of SST variability for the South Pacific. Thus, PDV appears to be a basin-wide phenomenon most likely driven from the tropics. Moreover, while it was already known PDV north of the equator could be adequately modeled as a reddened response to ENSO, our results indicate this is true to an even greater extent in the South Pacific.
Leif has a copy of the paper on his website that you can read here
Citation:
Shakun, J. D., and J. Shaman (2009), Tropical origins of North and South Pacific decadal variability, Geophys. Res. Lett., 36, L19711, doi:10.1029/2009GL040313.
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Stefan (12:04:29) :
gtrip (09:27:52) :
MUST READ:
http://www.quadrant.org.au/magazine/issue/2009/10/climate-modelling-nonsense
Thank you for that, it is a great piece.
Apparently the moderator didn’t think so as my post here and on a couple of other threads have been deleted (not even “snipped”).
My post was even deleted from the tips and notes page.
Is Joe Romm moderating this weekend????
Clive (07:33:07) :
There are ~ 250,000,000 tonnes of ocean water for every person on earth. (The math is ~ correct.)
That would be just the surface water.
“” F. Ross (10:19:04) :
“… These results highlight the strong similarity in Pacific decadal variability on either side of the equator and suggest it may best be viewed as a reddened response to ENSO.
…”
Pardon my red face but, in the context of the paper, what does reddened mean? [Possibly warmer?] “”
I suspect it means the PDO is mainly sensitive to the longer term variations in the ENSO (year to year instead of month to month)
The term may originate from the fact that red light has a longer wavelength than blue light.
glen martin (17:34:44) :
Thanks. Sounds plausible.
I hate to put a spanner in the works but simple logic tells you that this paper and the model it is based upon is a load of heiffer dust.
Please read my arguements at:
http://astroclimateconnection.blogspot.com/2009/10/which-came-first-chicken-or-egg.html
Cap’n Rusty and Michael…
Mods: This is a bit OT. Bear with me.
I was slightly off…
To be safe, use 200,000,000 cubic meters per person. With such huge numbers being off a wee bit is not critical. It is the concept (of BIG) one is trying to convey.
I did all of calculations again with some references. If you want a copy you can send an email to: clives at shaw dot ca
Here is the conclusion: For the purpose trying to form a mental image of this amount of water, it is suitable to say “there are about 200,000,000 cubic meters of sea water per person on earth.”
That is equivalent to a lake that measures 10 meters deep by 4,000 meters (4 km) by 5,000 meters (5km) PER PERSON.
A “lake” for a family of five therefore has about 1 billion cubic meters of seawater. This a body of water that is 10 meters deep by 10,000 meters (10 km) by 10,000 meters (10 km).
It is a lot of water. I feel insignificant when I try think how I might possibly have an affect on it. Maybe this line of thinking is silly, but it works for me. ☺
Clive
Gene… “That would be just the surface water.”
No, that is tonnage based on cubic meters. They are close to the same.
Has nothing to do with “surface.”
I initially uses tonnes. It is probably more sound to use cubic meters.
The figure was recalculated and is closer to 200,000,000 cubic meters. (And slightly more tonnes because sea water weights about 1.03 t/m3.)
Cheers!
Clive
Anna V.
For starters try:
Keeling and Whorf (1997) Proc. Natl. Acad. Sci., 94, pp. 8321 – 8328
“Possible Forcing of Global Temperature by the oceanic Tides”.
Keeling and Whorf (2000) PNAS, Vol 97., No. 8., pp. 3814 – 3819
“The 1800 year tidal cycle: A Possible Cause of Rapid Climate Change”.
Munk and Wunsch (1998) Deep Sea research Part 1, 44, pp. 1977 – 2010
“Abysmal Recipes II: Energetic of Tidal and Wind Mixing”
Egbert and Ray (2000) Nature, June 15th, Vol. 405, p. 775
“Significant Dissipation of Tidal Energy in the Deep Ocean Inferred from Satellite Altimeter Data”.
I apoligies if you have already heard of these references.
I am about to submit a paper for publication that shows that, between 1800 and 2002, the strongest extreme proxigean spring tides (EPST) that are nearest perihelion are preferrentially found in the starting years (or one year prior to the starting years) of El Nino events. Similarly, the weakest EPST that are near aphelion avoid the years leading up to El Nino events.
Ninderthana (22:06:24) :
thanks.
One more case of “the science is not settled”, imo.
Re: Ninderthana (18:13:35)
Thanks for the notes you left April 29, 2009:
“Misunderstandings about the Pacific Decadal Oscillation”
http://wattsupwiththat.com/2009/04/28/misunderstandings-about-the-pacific-decadal-oscillation/
[Ninderthana (05:52:17)]
anna v,
Links for some of the papers listed by Ninderthana:
Keeling, C.D.; & Whorf, T.P. (1997). Possible forcing of global temperature by the oceanic tides. Proceedings of the National Academy of Sciences of the USA 94(16), 8321-8328.
html:
http://www.pnas.org/content/94/16/8321.full
pdf:
http://www.pnas.org/content/94/16/8321.full.pdf
Keeling, C.D.; & Whorf, T.P. (2000). The 1800-year oceanic tidal cycle: A possible cause of rapid climate change. Proceedings of the National Academy of Sciences of the USA 97(8), 3814-3819.
html:
http://www.pnas.org/content/97/8/3814.long
pdf:
http://www.pnas.org/content/97/8/3814.full.pdf
Beyond this:
I recommend looking into the works of Yu.V. Barkin.
Several people have suggested above that “natural variation in the short term isunpredictable but the long term can be predicted”.
This really shows the limited knowledge of noise in natural systems of the writers. What they seem to be referring to is the properties of so called “normal”, “guassian” or “white noise”, which has equal power in equal frequency windows. This does have the property that long term noise is much smaller than short term noise and simple smoothing quickly reduces the noise.
However, there are plenty of systems where the noise level varies with frequency and 1/f noise aka (pink – i.e. reddy, low noise white) is quite typical of many natural systems. Such noise does not show the “it will all smooth out if we average enough points” of the naive commentators here. In contrast, because low noise predominates, averaging out can lead to INCREASING the amount of noise present. Or to put that in concrete terms, the natural noise of global temperature may well have noise components in the decadal, century and millennia time periods that are much larger than short term year-to-year variation.
For a totally impartial prediciton of global temperature see this graph:-
http://www.tursiops.cc/fm/pink.gif
from site: http://www.tursiops.cc/fm/
Mike,
Your arguments may have some meaning in a climate system whose variability is exclusively driven by internal fluctuations. However, it you are dealing with climate system that is being driven by an outside forcing agent
like the Moon (such as the PDO and ENSO) then you have a different kettle of fish.
I will soon be publishing evidence that shows that the onset of El Nino-ENSO events are synchronized with the onset of the strongest extreme proxigean spring tides (EPST). Not only that, I will be showing that the pumping frequencies of the EPST closely match those observed in the ENSO indices between 1950 and the present. They also naturally produce the observed 20 year and 65-70 year peridicities in the PDO as well.
Unfortunately, you are going to have to wait till I can get this work through peer-review before you can see the actual evidence.
Re: Ninderthana (07:25:07)
Have you ruled out the possibility of 2 (or more) varieties of El Ninos?
There are time-intervals for which there is rigid phase-concordance between contrasts of annual & interannual geomagnetic aa index and SOI (& for other climate indices as well).
Furthermore, wavelet-crosses of solar variables & terrestrial polar motion show patterns that match the time-integrated PDO. There appears to be a possible relationship with the period of ENSO; one of the patterns I’ve found is anything-but random (but I’ve not yet finished the analysis…)
Remember the phase-reversals in relationships between SST & solar cycles (that many have tried to sweep under the rug)?
Reminder – Figures 7 & 8:
Abarca del Rio, R.; Gambis, D.; Salstein, D.; Nelson, P.; & Dai, A. (2003). Solar activity and earth rotation variability. Journal of Geodynamics 36, 423-443.
http://www.cgd.ucar.edu/cas/adai/papers/Abarca_delRio_etal_JGeodyn03.pdf
Compare with:
http://www.sfu.ca/~plv/SSBx_LR.(67mo)_11.1a.png
http://www.sfu.ca/~plv/SSBy_LR.(67mo)_11.1a.png
http://www.sfu.ca/~plv/SSBz_LR.(67mo)_11.1a.png
Also: Compare with the JS-timescale (19.86a) pattern here …
http://www.sfu.ca/~plv/RegimeChangePoints.PNG
…and with …
http://www.sfu.ca/~plv/r_r.._12.8a.png
For reference:
ENSO Period (in years):
1) http://www.sfu.ca/~plv/PeriodAusSOI_MorletPi.PNG
using http://www.sfu.ca/~plv/WaveletMorletPi.PNG
2) http://www.sfu.ca/~plv/PeriodAusSOI_MxSh.PNG
using http://www.sfu.ca/~plv/WaveletComplexMexicanHat.PNG
Note: Power is time-normalized.
Compare change-points from the above with those here:
http://www.sfu.ca/~plv/Pr.-LR.(67mo)11.1a.png
This shows the phase-difference between terrestrial polar motion and the solar cycle at the (average) timescale of the solar cycle.
Supplementary:
Phase-contrast of solar cycle & stationary 11.1a wave:
http://www.sfu.ca/~plv/Stn11.1a_vs_LR.(67mo).png
Like it or not, the differences in culture are obvious and absolute. ,