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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.
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Figure 1
PACIFIC DECADAL OSCILLATION RECONSTRUCTIONS
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.
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Figure 2
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.
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Figure 3
GRAPHS, DATA LINKS, AND DATA CITATIONS OF INDIVIDUAL STUDIES
MacDonald and Case (2005)
Data Link:
ftp://ftp.ncdc.noaa.gov/pub/data/paleo/treering/reconstructions/pdo-macdonald2005.txt
DATA CITATION: MacDonald, G.M., and R.A. Case. 2006.
Pacific Decadal Oscillation Reconstruction for the Past Millennium.
IGBP PAGES/World Data Center for Paleoclimatology
Data Contribution Series # 2006-023.
NOAA/NCDC Paleoclimatology Program, Boulder CO, USA.
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.
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Figure 4
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D'Arrigo and Wilson (2006)
Data Link:
ftp://ftp.ncdc.noaa.gov/pub/data/paleo/treering/reconstructions/pdo-darrigo2006.txt
DATA CITATION: D'Arrigo, R. and R. Wilson. 2006.
Spring Pacific Decadal Oscillation Index Reconstruction.
IGBP PAGES/World Data Center for Paleoclimatology
Data Contribution Series # 2006-095.
NOAA/NCDC Paleoclimatology Program, Boulder CO, USA.
ORIGINAL REFERENCE: D'Arrigo, R. and R. Wilson. 2006.
On the Asian Expression of the PDO.
International Journal of Climatology. 26: 1607-1617.
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Figure 5
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Biondi et al (2001)
Data Link:
ftp://ftp.ncdc.noaa.gov/pub/data/paleo/treering/reconstructions/pdo.txt
DATA CITATION: Biondi, F. et al., 2001,
Pacific Decadal Oscillation Reconstruction.
International Tree-Ring Data Bank.
IGBP PAGES/World Data Center for Paleoclimatology
Data Contribution Series #2001-001.
NOAA/NGDC Paleoclimatology Program, Boulder CO, USA.
ORIGINAL REFERENCE: Biondi, F., A. Gershunov, and D.R. Cayan, 2001,
North Pacific decadal climate variability since AD 1661,
Journal of Climate, Volume 14, Number 1, January 2001.
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Figure 6
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Shen et al (2006)
Data Link:
ftp://ftp.ncdc.noaa.gov/pub/data/paleo/historical/pacific/pdo-shen2006.txt
DATA CITATION: Shen, C., et al. 2006.
Pacific Decadal Oscillation Reconstruction.
IGBP PAGES/World Data Center for Paleoclimatology
Data Contribution Series # 2006-045.
NOAA/NCDC Paleoclimatology Program, Boulder CO, USA.
ORIGINAL REFERENCE:
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.
doi:10.1029/2005GL024804.
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Figure 7
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D'Arrigo et al (2005)
Data Link:
ftp://ftp.ncdc.noaa.gov/pub/data/paleo/treering/reconstructions/pdo-darrigo2001.txt
DATA CITATION: D'Arrigo, R., et al. 2005.
Pacific Decadal Oscillation Reconstruction.
IGBP PAGES/World Data Center for Paleoclimatology
Data Contribution Series # 2005-020.
NOAA/NGDC Paleoclimatology Program, Boulder CO, USA.
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.
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Figure 8
ADDITIONAL PDO POSTS
Misunderstandings about the PDO – REVISED
Revisiting “Misunderstandings About The PDO – Revised”