The Three PDO Data Sets

In addition to the PDO data available from JISAO, there are two others maintained by NCDC. The two NCDC PDO data sets, based on ERSST versions 2 and 3, extend back to 1854, where the JISAO PDO only goes back to 1900.

JISAO:
http://jisao.washington.edu/pdo/PDO.latest

ERSST.v2:
ftp://ftp.ncdc.noaa.gov/pub/data/ersst-v2/pdo.1854.latest.ts

ERSST.v3:
ftp://eclipse.ncdc.noaa.gov/pub/ersst/pdo/pdo.1854.latest.ts

Figure 1 illustrates the relationship between the three. Some of the variations are due to the differences in computed SST for the North Pacific and the globe. Part of the difference is due the additional 46 years of data used in the standardization process. Which is correct? Assuming there are no calculation errors, all three are correct for the data sets employed .

http://i26.tinypic.com/25kn8ef.jpg
Figure 1

Note the variance in recent years between the JISAO and NCDC data. I believe it is more a result of standardization and not in the method used to compute SST. This leads me to believe the PDO should NOT be standardized, that true SST anomaly data should be illustrated, like the AMO.