  North Pacific sea surface temperatures (SST), as used in estimating the PDO,
are reanalyzed using state-space decomposition and subspace identification
techniques. The reanalysis presents a very different picture of SST in this
region. The first common trend reflects a global warming signal. The second
common trend modifies this for areas that underwent a sharper warming (cooling)
starting in the early 1970's. This trend is also related to dynamics in the
tropics and in Arctic sea ice extent. The third common trend is a superposition
of changes in pressure centers on the long-term global warming signal. The
fourth common trend is the trend that is contained in the original PDO series
if analyzed by state-space techniques, and is identical to the trend in the
North Pacific High. The first two common stochastic cycles capture the original
PDO and so-called "Victoria mode", showing that these series are dominated by
stationary behavior..
