pdo: PDO - Pacific Decadal Oscillation

In pbs-assess/PACea: An R package of Pacific ecosystem information to help facilitate an ecosystem approach to fisheries management

PDO – Pacific Decadal Oscillation

Description

The Pacific Decadal Oscillation is a monthly index which is a long-lived El Niño-like pattern of Pacific climate variability.

Usage

pdo

Format

A tibble also of class 'pacea_index' with columns:

year:

year of value

month:

month (1 to 12) of value

anom:

anomaly calculated as the leading empirical orthogonal function of monthly sea surface temperature anomalies over the North Pacific (poleward of 20 deg N) after the global average sea surface temperature has been removed. Note that the final value seems amenable to being recomputed when the time series is extended with further values (i.e. when we update pacea).

Details

Adapted from http://research.jisao.washington.edu/pdo/ The Pacific Decadal Oscillation (PDO) is a long-lived El Niño-like pattern of Pacific climate variability. While the two climate oscillations have similar spatial climate fingerprints, they have very different behavior in time. Fisheries scientist Steven Hare coined the term PDO in 1996 while researching connections between Alaska salmon production cycles and Pacific climate.

Two main characteristics distinguish PDO from El Niño/Southern Oscillation (ENSO): first, 20th century PDO "events" persisted for 20-to-30 years, while typical ENSO events persisted for 6 to 18 months; second, the climatic fingerprints of the PDO are most visible in the North Pacific/North American sector, while secondary signatures exist in the tropics, whereas the opposite is true for ENSO. Several independent studies find evidence for just two full PDO cycles in the past century: "cool" PDO regimes prevailed from 1890-1924 and again from 1947-1976, while "warm" PDO regimes dominated from 1925-1946 and from 1977 through (at least) the mid-1990's. Shoshiro Minobe has shown that 20th century PDO fluctuations were most energetic in two general periodicities, one from 15-to-25 years, and the other from 50-to-70 years.

Major changes in northeast Pacific marine ecosystems have been correlated with phase changes in the PDO; warm eras have seen enhanced coastal ocean biological productivity in Alaska and inhibited productivity off the west coast of the contiguous United States, while cold PDO eras have seen the opposite north-south pattern of marine ecosystem productivity.

Causes for the PDO are not currently known. Likewise, the potential predictability for this climate oscillation are not known. Some climate simulation models produce PDO-like oscillations, although often for different reasons. The mechanisms giving rise to PDO will determine whether skillful decades-long PDO climate predictions are possible. For example, if PDO arises from air-sea interactions that require 10 year ocean adjustment times, then aspects of the phenomenon will (in theory) be predictable at lead times of up to 10 years. Even in the absence of a theoretical understanding, PDO climate information improves season-to-season and year-to-year climate forecasts for North America because of its strong tendency for multi-season and multi-year persistence. From a societal impacts perspective, recognition of PDO is important because it shows that "normal" climate conditions can vary over time periods comparable to the length of a human's lifetime .

https://www.ncei.noaa.gov/access/monitoring/pdo/ The NCEI (NOAA's National Centers for Environmental Information) PDO index (used in pacea) is based on NOAA's extended reconstruction of SSTs (ERSST Version 5). It is constructed by regressing the ERSST anomalies against the Mantua PDO index for their overlap period, to compute a PDO regression map for the North Pacific ERSST anomalies. The ERSST anomalies are then projected onto that map to compute the NCEI index. The NCEI PDO index closely follows the Mantua PDO index.

Good explanation (and see figures) from https://www.worldclimateservice.com/2021/09/01/pacific-decadal-oscillation/ The Pacific Decadal Oscillation is a sea surface temperature (SST) climate cycle (or teleconnection) describing sea surface temperature anomalies over the Northeastern Pacific Ocean. The PDO can influence the weather conditions across North America with characteristic patterns occurring at different times of the year. The PDO oscillates between positive and negative phases. The positive phase is characterized by cool SSTs north of Hawaii and warmer than normal sea surface temperatures along the western coast of North America (their Figure 1). The negative phase is a mirror image with warm surface waters in the Central North Pacific and cooler than normal waters along the western coast of North America (their Figure 2).

Also, from https://en.wikipedia.org/wiki/Pacific_decadal_oscillation : 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). 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. This climate pattern also affects coastal sea and continental surface air temperatures from Alaska to California. A PDO 'signal' has been reconstructed as far back as 1661 through tree-ring chronologies in the Baja California area.

Associated code adapted from code generously shared by Chris Rooper.

Author(s)

Andrew Edwards

Source

Generated from running 'data-raw/coastwide-indices/coastwide-indices.R'.

Examples

## Not run: 
pdo
plot(pdo)

## End(Not run)

pbs-assess/PACea documentation built on April 17, 2025, 11:36 p.m.