Additionally sea surface temperature anomalies have some winter to winter persistence due to the reemergence mechanism.ĮNSO teleconnections, the atmospheric bridge ĮNSO can influence the global circulation pattern thousands of kilometers away from the equatorial Pacific through the 'atmospheric bridge'.

Thus, unlike El Niño–Southern Oscillation (ENSO), the PDO is not a single physical mode of ocean variability, but rather the sum of several processes with different dynamic origins.Īt inter-annual time scales the PDO index is reconstructed as the sum of random and ENSO induced variability in the Aleutian Low, whereas on decadal timescales ENSO teleconnections, stochastic atmospheric forcing and changes in the North Pacific oceanic gyre circulation contribute approximately equally. Several studies have indicated that the PDO index can be reconstructed as the superimposition of tropical forcing and extra-tropical processes. A PDO 'signal' has been reconstructed as far back as 1661 through tree-ring chronologies in the Baja California area. This PDO index is the standardized principal component time series. The Pacific decadal oscillation index is the leading empirical orthogonal function (EOF) of monthly sea surface temperature anomalies ( SST-A) over the North Pacific (poleward of 20°N) after the global average sea surface temperature has been removed. Hare, who noticed it while studying salmon production pattern results in 1997. The Pacific decadal oscillation was named by Steven R. This climate pattern also affects coastal sea and continental surface air temperatures from Alaska to California.ĭuring a ' warm', or 'positive', phase, the west Pacific becomes cooler and part of the eastern ocean warms during a 'cool', or 'negative', phase, the opposite pattern occurs. There is evidence of reversals in the prevailing polarity (meaning changes in cool surface waters versus warm surface waters within the region) of the oscillation occurring around 1925, 1947, and 1977 the last two reversals corresponded with dramatic shifts in salmon production regimes in the North Pacific Ocean. Over the past century, the amplitude of this climate pattern has varied irregularly at interannual-to-interdecadal time scales (meaning time periods of a few years to as much as time periods of multiple decades). The PDO is detected as warm or cool surface waters in the Pacific Ocean, north of 20°N. The Pacific decadal oscillation ( PDO) is a robust, recurring pattern of ocean-atmosphere climate variability centered over the mid-latitude Pacific basin.

Pdo file