Climate Observations: Is There A 60-Year Pacific Decadal Oscillation Cycle?
Is There A 60-Year Pacific Decadal Oscillation Cycle?
I've moved to WordPress. This post can now be found at Is There A 60-Year Pacific Decadal Oscillation Cycle?
INTRODUCTIONClimate bloggers often refer to a 60-year cycle in the Pacific Decadal Oscillation (PDO). I assume they derive the 60-year period from the graph of the PDO, Figure 1, from the JISAO "Pacific Decadal Oscillation (PDO)" web page. As illustrated the PDO data changes from positive to negative about 1945, reaches into positive values again about 1975, then appears to "switch" back to negative in the 2000s. Remarkably, this 60-year period is referred to even though the data before 1945 does not support a continuation before then. And referring to Paleoclimatological studies of the PDO, there is also no evidence of a persistent 60-year PDO cycle.
The NOAA Paleoclimatology Climate Reconstructions webpage includes 5 PDO reconstructions under the heading of Atmospheric Circulation Patterns. Figure 2 is a comparison graph of the data available from those studies. Note: All of the paleoclimatological PDO data in this post have been smoothed with a 30-year running-average filter to highlight the low frequency variability.
The longer-term dataset from MacDonald and Case (2005) skews the graph, so I've started the comparison in 1700 in Figure 3. There does not appear to be a persistent 60-year cycle in any of the PDO reconstruction datasets. If fact, there appears to be little agreement between the reconstructions prior to the early 1900s, but the datasets were, of course, based on different proxies and from different continents.
DATA CITATION: MacDonald, G.M., and R.A. Case. 2006.
Pacific Decadal Oscillation Reconstruction for the Past Millennium.
Data Contribution Series # 2006-023.
ORIGINAL REFERENCE: MacDonald, G.M., and R.A. Case. 2005.
Variations in the Pacific Decadal Oscillation over the past millennium.
Geophys. Res. Lett., 32, L08703, doi:10.1029/2005GL022478.
DATA CITATION: D'Arrigo, R. and R. Wilson. 2006.
Spring Pacific Decadal Oscillation Index Reconstruction.
Data Contribution Series # 2006-095.
ORIGINAL REFERENCE: D'Arrigo, R. and R. Wilson. 2006.
On the Asian Expression of the PDO.
International Journal of Climatology. 26: 1607-1617.
Journal of Climate, Volume 14, Number 1, January 2001.
DATA CITATION: Shen, C., et al. 2006.
Shen, C., W.-C. Wang, W. Gong, and Z. Hao. 2006.
A Pacific Decadal Oscillation record since 1470 AD reconstructed from proxy data of summer rainfall over eastern China.
Geophysical Research Letters, vol. 33, L03702, February 2006.
DATA CITATION: D'Arrigo, R., et al. 2005.
Data Contribution Series # 2005-020.
ORIGINAL REFERENCE: D'Arrigo, R., R. Villalba, and G. Wiles. 2001.
Tree-ring estimates of Pacific decadal climate variability.
Climate Dynamics, Volume 18, Numbers 3-4, pp. 219-224, December 2001.
Is there a monthly estimation of OHC available?
d: I haven't run across a monthly global OHC dataset yet. The NODC is quarterly and they've been updating within a month of the end of the last two quarters. Next one should be toward the end of next month hopefully.
Josh Willis 3 years ago had said he would provide monthly updates to OHC for public consumption. Quarterly is better than nothing though.
Historically, how do ENSO events affect OHC?
I don't think these proxies can tell you anything about whether PDO has any periodicity, since it is clear that most of them probably don't reflect the PDO's past variations, given the fact that they look nothing alike at all.
I've been meaning to thank you for your efforts in producing this site for months. It is superb.
Your post yesterday demonstrating the absence of the supposed 60yr PDO cycle has finally driven me to act.
I and doubtless many others come here for precisely this kind of data-centric, rigorous analysis.
Nothing else does such a good job of dispelling ignorance.
Please continue. You have created an invaluable resource.
(Since the above does not further any discussion of the actual post I do not expect you to show it in the comments).
The brief abstract states the following: "An ocean model, driven with surface boundary conditions from a recently completed atmospheric reanalysis of the first half of the twentieth century, is used to provide the first comprehensive description of the structure and evolution of the 1918/19 El Niño. In contrast with previous descriptions, the modeled El Niño is one of the strongest of the twentieth century, comparable in intensity to the prominent events of 1982/83 and 1997/98."
understanding of El Niño and a changing climate.
...hit the blogs in September.
I wrote, Not to discount the work by Giese et al: a quick look at a graph of NINO3.4 SST anomalies that includes the 30 years before 1900, Figure 1, reveals that there were two comparably sized "Super" El Nino events in 1877/78 and 1888/89.
Thanks again for the link. BTW, didn't Brett post something similar at Accuweather around that time?
Hello, and thank'ś for you very interesting posts.
plazamoyua: Thanks for the link and authors.
I watched your Youtube video on El Nino effects.
Is there a similarity between 97-98 El Nino and current? Should we expect another 'step change' in SST and surface temperatures?
With OHC being flat to a slight cooling the last several years, is it logical to postulate this El Nino may lead to steep drop in SST and surface temperatures in the coming months?
Joe Bastardi has recently eluded to the notion, not necessarily based on the above, that the current El Nino is pointing toward cold coming, not a resumption of global warming.
LT temps are sure rocketing upward this month. Looking at all the SST data you post, it sure looks like an enormous amount of heat being released.
d: You asked, "Is there a similarity between 97-98 El Nino and current?"
The 1997/98 El Nino was a traditional (central and eastern tropical Pacific) El Nino. The 2009/10 El Nino was an El Nino Modoki. It was a central tropical Pacific El Nino.
You asked, "Should we expect another 'step change' in SST and surface temperatures?"
If there is a significant La Nina, the east Indian and West Pacific Oceans should respond with an upward shift.
Part of the apparent shift in TLT and LST anomalies in the mid-to-high latitudes of the Northern Hemisphere resulted from the AMO, which was rising until 2005 and helping to maintain the temps at post 1997/98 El Nino levels. But the North Atlantic SST anomalies have been dropping since around 2005, so I can't say for sure that the shift will be as obvious.
"If I am not wrong, the idea of the 60 year cycles related to climate"
The Chinese calender has two parts, a 12 year cycle and a 60 year cycle.
The 12 year cycle tracks roughly with sunspots.
The question is what does the 60 year cycle track with.
An astrologer would say it's when Jupiter and Saturn align. Jupiter and Saturn Align every 20(score) years, and align in roughly the same place in 60 years.
An astrophysicist would agree that the alignment of Saturn and Jupiter every 60 years has meaning, as Saturn and Jupiter determine the center of mass of the Solar System.
How the 60 year cycle plays out in earth's climate system is a bit of a mystery.
I find it interesting that there IS so little consistency among the several attempts. It may the effect of different continents, different analyses, and different researcher "tweaks" to the paleorecord, or a combination of the above. In the end, I suggest it underscores that paleoclimatology is a facet of science that has yet to be adequately established as having sufficient reliability on which to base major public policies. (In researcher lingo: "Needs more study.") The 30-year smoothing may also serve to hide things.
Also, I note an interesting relationship (beyond how they all come together after about 1950, in the instrument age). That is that D'Arrigo's work is almost completely a reverse of the plot of MacDonald. That relationship appears to fail after about 1900, however, but prior to then the inverse relationship appears very good.
Finally, I have seen other postings suggesting that the PDO may actually be comprised of several different oscillations of different periocidies. Given also the recent (2009?) establishment of the Central pacific El Nino (or El Nino Modoki), it may merely serve to show how much we have yet to learn.
Got here via your recent WUWT ref. First thought was, All the proxies are suspect, with that pre-instrumental divergence. Then I looked at individual reconstructions and the Shen recon just felt plausible. Trying to analyse and explain, my first thought was, there is a steady PATTERN ie nothing wildly unusual last 100 years, just evidence of cyclicity. And it fits the recently observed 60-year-approx cycle. Then I noticed that Shen used "proxy data for summer rainfall over eastern China" whereas all the others used treering data.
Just noticing. It does feel better and better, and though it scarcely constitutes proof, it is a lead to follow IMHO.
Incidentally, the astrophysics of the 60-year cycle is a bit more complex than Harrywr2 says. Jupiter and Saturn are CONJUNCT every 20 years, but each conjunction is nearly exactly 120° offset from the one before, thus after 60 years the (4th) conjunction returns to almost exactly the same position as the first. There may well be harmonics with other planets significant regarding the solar system barycentre, that only kick in every 60 years but I don't know. Tallbloke might know.