Digital Diatribes

A presentation of data on climate and other stuff

Pacific Decadal Oscillation (PDO) Index – Back into the Negative

Posted by The Diatribe Guy on December 4, 2008

The PDO index is a measure of another one of those weird oceanic oscillation patterns.  The ENSO index is a shorter-term varying event, whereas the PDO index is considered a longer-term event.  Interestingly, however, when you collapse the ENSO index into longer average time periods, there does appear to be persistency in the ENSO index, as well. However, the short-term cyclical nature of the ENSO index is much more evident than the PDO index, even if the averages show similar persistency.

The PDO index is predominant in the Northern Pacific and secondarily evident in the tropics, whereas the ENSO index is the other way around. ENSO receives so much attention because of the large short-term cyclical variations, but the PDO has very significant swings as well, just usually over a longer period of time.

The index, however, is measured on a month-to-month basis and the data can be located here.

November has not yet been updated, but the October index value was -1.76. This was the single coolest reading in any month since November 1999, and was the 14th consecutive negative reading in a row. While there have been other stretches of 14 consecutive negative readings – the last being 1999-2000, it is interesting to note that the current streak of seven consecutive readings of less than -1 has not been seen since the period ending February 1976. That particular stretch ended at 7 months. If this month’s reading is below -1, it will mark the first time since the period ending June 1972. And that streak ended at 8. Beyond that point takes us to a streak in the early 1960s. So I’ll keep an eye on that.

As I did with the ENSO index, I collapsed the raw data into different average periods. Since the PDO does seem to vary over a longer period of time, I went up to a 10 year average. The persistency in the index is very clear once you take longer-term averages.

Below are a few charts of the PDO. The first is the raw data. Taking the edges off with 12-month smoothing follows that. I then present 5-year and 10-year averages.

The PDO monthly index has been negative for a bit already, as has the five-year average. But the 10-year average recently went negative, as well. Of course, all the same arguments apply as in the ENSO discussion – the persistence matters. You keep a heater running and the temperature gets warmer than the temperature an hour ago, depending on insulatory effects. Persistence in both ENSO and PDO correspond with the warming we see in the global temperature readings. The 10-year average PDO is slightly negative, and we’ve cooled slightly in the last few years. Coincidence?

Raw PDO Data since 1900

The overall PDO index data since 1900.

12-month average PDO index

The overall PDO index data since 1900 with 12-month smoothing.

5-year average PDO index

The overall PDO index data since 1900 with 5-year smoothing.

10-year average PDO index

The overall PDO index data since 1900 with 10-year smoothing.

The more I look at all these indices and see the same general pattern (overall average increase in sunspots during the time period of warming, overall increased persistence in ENSO index during the period of warming, and overall increased persistence in the PDO index duiring the period of warming) the more I realize how many different events have simply lined up in favor of the warming we saw from the 1970s to the late 1990s. How these things manage to get ignored in favor of simple correlation charts between temperature and CO2 (which always end around 2000 because the correlation breaks down after that) is utterly amazing.


14 Responses to “Pacific Decadal Oscillation (PDO) Index – Back into the Negative”

  1. Fran Manns, Ph.D., P.Geo. (Ontario) said

    Here is another interesting correlation with th usual proviso that correlation is not causation. Sorry the table is hard to read. I’m a rooky at this.

    Table ?: Ten sunspot maxima and ten minima correspond to monsoon rainfall variation. Seven years do not correspond. Four solar extremes extend over two years.

    Year Sunspots Rain (mm) correlate not Peak Trough
    1848 124.7 756 1 1
    1856 4.3 827 1 1
    1866 16.3 841 1 1
    1867 7.3 841 1 1
    1870 139.0 884 1
    1878 3.4 917 1 1
    1879 6.0 918
    1883 63.7 827 1 1
    1889 6.3 908 1 1
    1893 85.1 902 1 1
    1901 2.7 728 1
    1905 63.5 715 1 1
    1913 1.4 803 1
    1917 103.9 995 1
    1923 5.8 845 1
    1928 77.8 743 1 1
    1933 5.7 996 1 1
    1937 114.4 863 1 1
    1938 109.6 860
    1944 9.6 921 1 1
    1947 151.6 922 1 1
    1948 136.3 854
    1954 4.4 903 1
    1957 190.2 755 1 1
    1964 10.2 926 1 1
    1968 105.9 766 1 1
    1976 12.6 871 1 1
    1977 27.5 932
    1979 155.4 720 1 1
    1986 13.4 752 1
    1996 8.6 875 1 1
    Mean 57.0 850.5 20 7 10 10
    S.D. 59.6 78.5 74% 26%

  2. Fran Manns, Ph.D., P.Geo. (Ontario) said

    The third most important greenhouse gas is CO2, and it does not correlate well with global warming or cooling either; in fact, CO2 in the atmosphere trails warming which is clear natural evidence for its well-studied inverse solubility in water: CO2 dissolves in cold water and bubbles out of warm water. The equilibrium in seawater is very high, making seawater a great ‘sink’; CO2 is 34 times more soluble in water than air is soluble in water.

    Correlation is not causation to be sure. The causation has been studied, however, and while the radiation from the sun varies only in the fourth decimal place, the magnetism is awesome. As I understand it, the hypothesis of the Danish National Space Center goes as follows:

    Quiet sun → reduced magnetic and thermal flux = reduced solar wind → geomagnetic shield drops → galactic cosmic ray flux → more low-level clouds and more snow → more albedo effect (more heat reflected) → colder climate

    Active sun → enhanced magnetic and thermal flux = solar wind → geomagnetic shield response → less low-level clouds → less albedo (less heat reflected) → warmer climate

    That is how the bulk of climate change might work, coupled with (modulated by) sunspot peak frequency there are cycles of global warming and cooling like waves in the ocean. When the waves are closely spaced, the planets warm; when the waves are spaced farther apart, the planets cool.

    Check the web site of the Danish National Space Center.

    Using a box of air in a Copenhagen lab, physicists traced the growth of clusters of molecules of the kind that build cloud condensation nuclei. These are specks of sulphuric acid on which cloud droplets form. High-energy particles driven through the laboratory ceiling by exploded stars far away in the Galaxy – the cosmic rays – liberate electrons in the air, which help the molecular clusters to form much faster than atmospheric scientists have predicted. That may explain the link proposed by members of the Danish team, between cosmic rays, cloudiness and climate change.

    The ultimate cause of the solar magnetic cycle may be cyclicity in the Sun-Jupiter centre of gravity. We await more on that. In addition, although the post 60s warming period is over, it has allowed the principal green house gas, water vapour, to kick in with humidity, clouds, rain and snow depending on where you live to provide the negative feedback that scientists use to explain the existence of complex life on Earth for 550 million years. The planet heats and cools naturally and our gasses are the thermostat.

    Keeping in mind that windmills are hazardous to birds, be wary of the unintended consequences of the all-knowing environmental lobby groups.

    Fran thanks for your comments. You may be interested in taking a look at the sunspot charts I put together (just click on the category to the left). Also, the Center of Mass of the Solar System theory as it relates to the impact of sunspots is something that was central to the work of Theodor Landscheidt. Many people have different opinions of his work, but I have been very intrigued by it. I have a “Landscheidt” category to the left, as well, that you may find interesting. I have inteded to do more in that category, but there are only so many hours in a day…

  3. Jeff Id said

    The last graph really brings out the trends. It will be interesting to see how much temps drop from this across the US. I wonder how much people will be willing to spend for global warming if they are shoveling three feet of snow out of their east coast driveway.

    After some short review, this looks like it could be a major driver for the northern hemisphere- especially north america. There is a cross-sectional map of temps from watts up which is pretty interesting. It was provided by Bob Tisdale in the thread.

  4. The Diatribe Guy said

    The November anomaly was once again less than 1. (-1.26)

    And I did read the commentary about how PDO is actually “leaking” it’s effect to the area of the Pacific where ENSO is measured, kind of inducing a La Nina of sorts. I guess it’s fun to debate whether it’s really La Nina or not, but common sense tells me that it doesn’t matter what you call it, the temperature of the Ocean is cool. Plus, I didn’t hear such counter-arguments about El Nino being driven by warm PDO. Nevertheless, it’s only reasonable to assume that one does have some effect on the other. But at the end of the day, the weather will be impact. If the whole freaking Pacific is cold, it means that our weather will be impacted.

  5. […] Warmest November in Human History! (aka: December 2008 Update on Global Temperature – HadCrut)Pacific Decadal Oscillation (PDO) Index – Back into the NegativeNovember 2008 Update on Global Temperature – HadCrutNovember 2008 Update on Global Temperature – […]

  6. Matt said

    Really nice site you have here. I like you you have presented to the data. Easy to follow. I love statistics and much prefer to see the raw data – or at least how you’ve presented it – so I can interpret it, or at least ponder it, myself rather than being spoonfed third party opinion pieces based on pre-interpreted, highly summarized data sets.

    Much, much better than majority of ‘professional/commercial’ sites I’ve seen.

    Well done. Keep up the good work.

  7. Matt said

    geez, just read my reply. Apologize for the grammatical errors. Should have proof read it first.

  8. […] the Atlantic Multidecadal Oscillation (AMO) IndexSeptember 2008 Update on Global Temperature – RSSPacific Decadal Oscillation (PDO) Index – Back into the NegativeDecember 2008 Update on Global Temperature – GISSFull Eclipse Coming, and The Lunar Cycle (2nd in a […]

  9. clover said

    But, the PDO index you’ve shown here already removes the global trend in SST..So, you’re not looking at pacific temperatures directly. you’re just looking at a natural pattern that’s imposed on a global trend. I don’t understand what this has to do with correlating temperature and co2…

  10. The Diatribe Guy said

    The entire point is that the pattern impacts temperature, because it is a long cycle. In the 30 year phase of the positive anomaly, it stands to reason that this will continue to promote elevated temps. And the impact will be cumulative. Likewise, when the cooling cycle is predominant, temps will decline.

    By no means does this imply that the PDO is the only driver of temperature, but it is certainly a driver. Further, I do not agree with your hypothesis that the SST trend is “removed.” Even if I buy this on a long-term basis, I do not buy it on a cyclical basis. And since AGWers like to focus on 30-year trends and extrapolate them, and the PDO has a half-phase of 30-33 years, it is entirely relevant to consider the cyclical temperature effects of these oscillations.

  11. Fernando said

    Well, and PDO index jan- 2009 ?????

  12. The Diatribe Guy said

    Good question. The file still hasn’t been updated.

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  14. […] e si raffreddano periodicamente. La più importante di queste oscillazioni è quella decennale del PDO (Pacific Decadal Oscillation), è un anomalia che si riscontra sulle superfici oceaniche che […]

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