The PDO is NOT a Simple Residual Like the AMO.
People understand the Atlantic Multidecadal Oscillation (AMO). It's calculated very simply; subtract Global SST (sea surface temperature) anomalies from the North Atlantic SST anomalies. This simple process has been said to remove the global warming signal from the AMO. Many people believe the Pacific Decadal Oscillation (PDO) is calculated using the same basic equation, but it's not. According to Nathan Mantua of JISAO, the details of how the PDO is calculated are found in this paper:
ENSO-like Interdecadal Variability: 1900–93
Calculating the PDO is a multistep process. It includes creating an SST anomaly time series for each 5 degree grid of the North Pacific (North of 20N), calculating the residual for each grid, and computing the EOFs ( empirical
orthogonal function) of these North Pacific residual SST anomaly fields. The PDO index is the leading PC (principal component) of that analysis. It's far from a simple process.
The PDO has been found to be a function of ENSO. In "ENSO-Forced Variability of the Pacific Decadal Oscillation", Newman et al state in the conclusions, "The PDO is dependent upon ENSO on all timescales."
A few months ago, I discovered the instructions for retrieving Smith and Reynolds ERSST.v2 data (extended reconstructed SST) from the NOAA NOMADS system based on user selected dates and global coordinates:
http://www.ncdc.noaa.gov/oa/climate/research/sst/ERSST-ts.txt
One of the first data sets I downloaded was the time series of SST anomalies for the North Pacific, 20 to 65N, what I called the Mid-Latitude North Pacific SST Anomaly in the following graph. Note the 0.9 deg C drop then rebound in temperature from the late 19th to the mid-20th centuries. It's tough to miss. It certainly appears to be related to Meridional Overturning Circulation (MOC), not ENSO.
http://i25.tinypic.com/2cyg07k.jpg
Using the same simple process employed to calculate the AMO, that is, subtracting the Global SST Anomaly from the Mid-Latitude North Pacific Anomaly, provides a data set that I've dubbed the North Pacific Residual.
http://i28.tinypic.com/jrwjk6.jpg
The North Pacific Residual bears no resemblance to the PDO. In fact, note that I had to scale the PDO to bring it back into line with the data set from which it is extracted. (The PDO data illustrated is from the ERSST.v2 data set, not the JISAO version. The curves of the two PDO data sets are similar, but the ERSST.v2 data extends further back in time.)
http://i27.tinypic.com/2n1sv49.jpg
When compared to the AMO, the two Northern Hemisphere SST oscillations complement one another from the 1920s to present. Prior to that, they were out of synch, offsetting their individual impacts on global temperature. It is no coincidence that Northern Hemisphere and global temperatures follow the rises and falls of these two residual anomalies.
http://i30.tinypic.com/11kv7r5.jpg
CLOSING
Past studies have estimated the contribution of the AMO to the rises and falls of Northern Hemisphere and Global temperatures over the 20th century. I would think that the North Pacific Residual would contribute similarly. Shouldn't climatologists and climate change bloggers have another index of North Pacific temperature anomalies, one that could be used to determine the effect of the North Pacific SST oscillation on Northern Hemisphere and Global temperatures?
SOURCES
The links and graphs are from my series on Smith and Reynolds SST data:
http://bobtisdale.blogspot.com/2008/06/smith-and-reynolds-sst-posts.html
Sea Surface Temperature Data is Smith and Reynolds Extended Reconstructed SST (ERSST.v2) available through the NOAA National Operational Model Archive & Distribution System (NOMADS):
Luke: Whenever I see quasi-decadal in the title or abstract of a paper, I presume the author is avoiding the use of TSI or solar influence, since the solar cycles are quasi-decadal. Many times I’m right. Why they shy away from solar in the title is beyond me. Unfortunately, the term quasi-decadal oscillation is applied to any number of variables, like precipitation in your linked paper, so I can't isolate what you're referring to.
As for the IPO: According to Chris Folland of Hadley Centre, "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." He concludes that opening paragraph in the following with, "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."
ftp://www.iges.org/pub/kinter/c20c/IPO.doc
I've covered the PDO-ENSO relationship in a number of posts at my blogspot. At the end of the second linked post is a quote from a paper that states, "The PDO is dependent on ENSO on all timescales." It may also appear in the first link.
http://bobtisdale.blogspot.com/2008/06/common-misunderstanding-about-pdo.html
http://bobtisdale.blogspot.com/2008/06/chicken-or-egg-pdo-or-enso.html
The three PDO data sets (JISAO, ERSST.v2, ERSST.v3) are discussed here:
http://bobtisdale.blogspot.com/2008/06/three-pdo-data-sets.html
If we assume the PDO is dependent on ENSO, is there enough of a correlation between the PDO and the IPO to assume that the IPO is also dependent on ENSO?
The following three graphs illustrate the correlation between the PDO and IPO. The first is raw data. Note: There aren't any 5 and 6 deg C basin-wide oscillations in the Pacific. The amplification of the signal is a result of the statistical process they use to extract the IPO from Pacific SST data. (The same note applies to the PDO, as well.)
http://i33.tinypic.com/vpg4l2.jpg
In the second, I've smoothed the data with a 37-month filter.
http://i33.tinypic.com/2e6c8eq.jpg
In the third, I've scaled the IPO to highlight the correlation with the PDO. There are some minor variances, just as there are differences between the three PDO data sets.
http://i38.tinypic.com/nz69y.jpg
I hope that helps. I haven't yet gotten around to graphically comparing the PDO and NINO3.4. Someday.
Bob - not sure where this fits but there appears to be quasi-decadal components as well.
Journal of Climate
Volume 18, Issue 1 (January 2005)
Rainfall Variability at Decadal and Longer Time Scales: Signal or Noise?
http://www.bom.gov.au/bmrc/clfor/cfstaff/sbp/journal_articles/holger_jclim_2005.pdf
I'm now confused where PDO, IPO and quasi-decadal fits together. Or echoes of the same process ?
Not talking about biogenic pulses of CO2 at all. No way. No whichaway (trivial effect).
A complete and utter misunderstanding by Gary!
FACTS SHEET:
Marine cyanobacteria absorb CO2 and bicarbonate from seawater (subject to the constraints of SST) and emit O2. In so doing they:
(1) In some cases secrete biogenic calcite i.e. the coccolithophores. Blooms of this give the sea surface a much enhanced albedo.
(2) All cyanobacterial blooms cause the sea to be covered with monoloayers or thicker of lipids, sterols etc due to predation by zooplakton and cell lysis by cyanobacteriophages (viruses if you will). This reduces the rate of evaporation relative to a sea surface without monolayers etc. For example, for years long chain alcohols have been used to lower evaporation of water surface in reservoirs etc. There are textbooks on this.
(2) Cyanobacteria emit a compound which decomposes into dimethylsulfide (DMS) which passes into the air. This nucleates low level cloud, not only releasing latent heat but further increasing low level albedo and lowering SST (therby increasing CO2 solubility and so on and so forth).
Marine cyanobacterial blooms have profund effects on SST, surface and low altitude albedo and cloud mass, relative humidity and lapse rate. They can be thousands of km2 in size. They are easily photographed and studied from satellites.
Go figure......
Bob's comparison of SO and Global anomalies reinforces my conclusion: partial pressure of CO2 is the 800 lb. gorilla.
Biogenic pulses simply don't fit the seasonal signal; they fall off while the SS temperature is still peaking.
Steve Short: Hot off the press, which means I haven't spent a lot of time looking at the results.
The first graph is a comparison of Mid-Latitude South Pacific and Global SST Anomalies.
http://i38.tinypic.com/6rrhna.jpg
The second graph is the requested South Pacific Residual.
http://i36.tinypic.com/166azph.jpg
Interesting, I had intended to write this up earlier but never got to it. The Mauna loa data set also shows a shortening of the interval between maximum and minimum annual values over the past four decades of 2 to 3 weeks. Ralph Keeling hadn't noticed it when I spoke to him about it so he detrended the data and it was still there.
This has contributed to some of the build up in CO2 and would be consistent with a shorter growing season that has absorbed less carbon. The only problem is that the temperature data has not reconciled.
One plausible explanation could be that improved annual crop varieties have shortened the growing season and have reduced the CO2 absorption required to produce a crop.
This:
http://i30.tinypic.com/11kv7r5.jpg
shows that the amplitudes of the NPR residual are decreasing with time while the amplitudes of the AMO are not.
How about a SPR?
Further to this. I forgot to point that it can be equally misleading (and fairly unproductive) to just look at absolute CO2 levels.
We know that it is (now) the anthropogenic input which is the the principal component of (positive) change in absolute CO2 levels. Hence I have been looking for possible indirect climatic effects of that principal comment. The oceans are clearly the places to look.
Just as Bob has described the derivation of the AMP and the (different) PDO above, I have for some time been looking at, in effect, the residuals between NOAA-computed monthly global means for atmospheric CO2 and monthly means over whole regions - in this case the SO especially, OR residuals between other well defined locations (showing near constant rates of change) and regions of the planet.
As Bob and Cohenite would agree, this is one of the best ways to tease out cause and effect.
Maybe I'll just have to start providing some definitions and acronyms for my C-based residuals so they start looking as sexy as T-based residuals.
Hi Ian
In a nutshell, what I am NOT saying is that CO2 is driving climate strongly via the so-called Greenhouse Effect - as we now know there are a significant number of negative feedbacks which show the overall CO2 sensitivity is low - probably significantly less than 1.5 C (and maybe less than 0.5 C - but I'm not betting on it).
However, what I think we are really missing here is the response of the global oceanic CO2 system of: surface dissolution, CO2 fertilization of primary productivity stimulation and subsurface conveying' to (variously) increased atmospheric CO2 either anthropogenic or for other reasons at various times (in terms of effect on weather).
Significant nutrient supply variation in atmospheric CO2 AND N, Fe and Si (the latter 3 via continental dust and volcanic fallout on the oceans), in my view, induces significant variations in regional, oceanic and global climate principally via the 'spin-off' effects of cyanobacterial blooming, i.e. the albedo, SST, relative humidity and lapse rate effects described previously.