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<onlyinclude>'''Pacific Decadal Oscillation (PDO)''' is a long term [[ocean]] fluctuation of the Pacific Ocean causing [[Sea surface temperature| sea surface temperatures]] to cool or warm over extended periods of time. The PDO fluctuates in its phases approximately every 20 to 30 years.<ref name=RE2>”Pacific Decadal Oscillation (PDO)", Sealevel.jpl.nasa.gov. [Online]. Available: http://sealevel.jpl.nasa.gov/science/elninopdo/pdo/. [Accessed: 19- May- 2016].</ref> PDO broadens to cover the whole Pacific Basin which known as the [[InterDecadal Pacific Oscillation]] (IPO).</onlyinclude> The PDO is a [[Modes of climate variability|natural form of climate variability]], explaining short and long phases in climate caused by natural, large scale features. Other [[modes of climate variability]] include the [[Atlantic Multidecadal Oscillation]], [[Northern Annular Mode]], [[North Atlantic Oscillation]], and more.
[[File:Pdo warm cool3.jpg|thumb|450x450px|Figure 1. On the left, a ''warm phase'' (positive) of the Pacific Decadal Oscillation (PDO). On the right, a ''cool phase'' (negative) of the PDO.<ref name=":0" />]]
<onlyinclude>'''Pacific Decadal Oscillation (PDO)''' is a long term [[ocean]] fluctuation of the Pacific Ocean causing [[Sea surface temperature| sea surface temperatures]] to cool or warm over extended periods of time. The PDO fluctuates in its phases approximately every 20 to 30 years.<ref name="RE2">”Pacific Decadal Oscillation (PDO)", Sealevel.jpl.nasa.gov. [Online]. Available: http://sealevel.jpl.nasa.gov/science/elninopdo/pdo/. [Accessed: 19- May- 2016].</ref> PDO broadens to cover the whole Pacific Basin which known as the [[InterDecadal Pacific Oscillation|Interdecadal Pacific Oscillation]] (IPO).</onlyinclude> The PDO is a [[Modes of climate variability|natural form of climate variability]], explaining short and long phases in climate caused by natural, large scale features. Other [[modes of climate variability]] include the [[Atlantic Multidecadal Oscillation]], [[Northern Annular Mode]], [[North Atlantic Oscillation]], and more.


The PDO is frequently described as an extended [[El Nino| El Niño]] like pattern of Pacific climate.<ref name="RE1">"Pacific Decadal Oscillation (PDO) | Teleconnections | National Centers for Environmental Information (NCEI)", Ncdc.noaa.gov, 2016. [Online]. Available: https://www.ncdc.noaa.gov/teleconnections/pdo/. [Accessed: 19- May- 2016].</ref> Pacific Ocean has a large impact on global [[weather]] [[climate]]. Research has shown when PDO is in a warm phase, global [[temperature]]s tend to increase and global temperatures tend to cool down when in a cool phase.<ref name=RE2/> In the cool phase, cool waters wrap in a horseshoe shape around a core of warmer than average water. In the warm phase, this process is reversed.<ref name=RE2/> Over the last hundred years, we have had only a handful of phase shifts:<ref name=RE2/>
The PDO is frequently described as an extended [[El Nino| El Niño]] -like pattern of Pacific climate.<ref name="RE1">"Pacific Decadal Oscillation (PDO) | Teleconnections | National Centers for Environmental Information (NCEI)", Ncdc.noaa.gov, 2016. [Online]. Available: https://www.ncdc.noaa.gov/teleconnections/pdo/. [Accessed: 19- May- 2016].</ref> The Pacific Ocean has a large impact on global [[weather]] [[climate]]. Research has shown when PDO is in a ''warm phase'', global [[temperature]]s tend to increase, and when in a ''cool phase'', global temperatures tend to decrease.<ref name="RE2" /> In the cool phase, cool waters wrap in a horseshoe shape around a core of warmer than average water. In the warm phase, this process is reversed.<ref name="RE2" /> See Figure 1 above for a visual representation of these temperature phases.
:
[[File:Pdo.timeseries.sstens.png|thumb|590x590px|Figure 2. Warm and cold phase series of shifts in the Pacific Decadal Oscillation.<ref name=":0">National Oceanic and Atmospheric Administration (2016). (Accessed July 9, 2026). ''Pacific Decadal Oscillation (PDO)'' [Online]. Available: https://psl.noaa.gov/pdo/</ref>]]
:*                              1905 - PDO switched to warm phase
Over the last hundred years, we have had only a handful of phase shifts.<ref name="RE2" /> Figure 2. Graphs these shifts in the Pacific Decadal Oscillation.
:*                              1946 - PDO switched to cool phase
:*                              1977 - PDO switched to warm phase
:*                              2008 - PDO switched to cool phase


[[File:Figure_PDO-01.JPG|thumb|650px|center|Figure 1. Warm and cold phase series of shifts in the Pacific Decadal Oscillation
'''1905:''' switch to warm phase
<ref>National Oceanic and Atmospheric Administration. (July 22, 2016). ‘’PDO Modes’’ [Online]. Available: https://www.nwfsc.noaa.gov/research/divisions/fe/estuarine/oeip/figures/Figure_PDO-01.JPG</ref>]]


When sea surface temperatures are unusually cool in the interior North Pacific, warm along the Pacific Coast, and sea level pressures are below average over the North Pacific, the PDO has a positive value.<ref name=RE1/> When the climate anomaly patterns are reversed, with warm sea surface temperature anomalies in the interior and cool sea surface temperature anomalies along the North American coast, or above average sea level pressures over the North Pacific, the PDO has a negative value.<ref name=RE1/> The PDO is highly correlated with sea surface temperature in the northern California Current (CC) area.<ref name=RE3>"Pacific Decadal Oscillation (PDO)", NOAA. [Online]. Available: https://www.nwfsc.noaa.gov/research/divisions/fe/estuarine/oeip/ca-pdo.cfm. [Accessed: 20- May- 2016].</ref> These phases result from the direction of winter [[wind]]s in the North Pacific: winter winds blowing primarily from the southwest result in warmer conditions in the northern CC.<ref name=RE3/> The CC warms at such times due to onshore transport of warm waters that normally lie offshore. Conversely, when winds blow primarily from the north, upwelling occurs both in the open ocean and at the coast, leading to cooler conditions in the northern CC.<ref name=RE3/>
'''1946:''' switch to cool phase
 
'''1977:''' switch to warm phase
 
'''2008:''' switch to cool phase
 
 
 
 
 
The PDO has a ''positive value'' when: sea surface temperatures are unusually cool in the interior North Pacific, warm along the Pacific Coast, and sea level pressures are below average over the North Pacific.<ref name="RE1" /> When the climate anomaly patterns are reversed, the PDO has a ''negative value'': with warm sea surface temperature anomalies in the interior and cool sea surface temperature anomalies along the North American coast, or above average sea level pressures over the North Pacific.<ref name="RE1" />  
 
The PDO is highly correlated with sea surface temperature in the northern California Current (CC) area.<ref name="RE3">"Pacific Decadal Oscillation (PDO)", NOAA. [Online]. Available: https://www.nwfsc.noaa.gov/research/divisions/fe/estuarine/oeip/ca-pdo.cfm. [Accessed: 20- May- 2016].</ref> These phases result from the direction of winter [[wind]]s in the North Pacific: winter winds blowing primarily from the southwest result in warmer conditions in the northern CC.<ref name="RE3" /> The CC warms at such times due to onshore transport of warm waters that normally lie offshore. Conversely, when winds blow primarily from the north, upwelling occurs both in the open ocean and at the coast, leading to cooler conditions in the northern CC.<ref name="RE3" />


==How PDO Impacts Climate==
==How PDO Impacts Climate==
The change in location of the cold and warm water masses alters the path of the [[jet stream]]. The jet stream in the northern hemisphere delivers storms across the United States. The PDO phase that we appear to have entered will act to steer the jet stream further north over the Western Canada and The United States.<ref name="RE4”>"Pacific Decadal Oscillation (PDO): Definition and Indices | NCAR - Climate Data Guide", Climatedataguide.ucar.edu. [Online]. Available: https://climatedataguide.ucar.edu/climate-data/pacific-decadal-oscillation-pdo-definition-and-indices. [Accessed: 23- May- 2016].</ref>
The change in location of the cold and warm water masses alters the path of the [[jet stream]]. The jet stream in the northern hemisphere delivers storms across the United States. The PDO phase that we appear to have entered will act to steer the jet stream further north over the Western Canada and The United States.<ref name="RE4”>"Pacific Decadal Oscillation (PDO): Definition and Indices | NCAR - Climate Data Guide", Climatedataguide.ucar.edu. [Online]. Available: https://climatedataguide.ucar.edu/climate-data/pacific-decadal-oscillation-pdo-definition-and-indices. [Accessed: 23- May- 2016].</ref>
== For Further Reading ==
* [[Modes of climate variability]]
* [[Ocean]]
* [[Sea surface temperature]]
* [[Atlantic Multidecadal Oscillation]]
* Or explore a [[Special:Random|random page]]


==References==
==References==
{{reflist}}
{{reflist}}
[[Category: Uploaded]]

Revision as of 18:12, 9 July 2026

Figure 1. On the left, a warm phase (positive) of the Pacific Decadal Oscillation (PDO). On the right, a cool phase (negative) of the PDO.[1]

Pacific Decadal Oscillation (PDO) is a long term ocean fluctuation of the Pacific Ocean causing sea surface temperatures to cool or warm over extended periods of time. The PDO fluctuates in its phases approximately every 20 to 30 years.[2] PDO broadens to cover the whole Pacific Basin which known as the Interdecadal Pacific Oscillation (IPO). The PDO is a natural form of climate variability, explaining short and long phases in climate caused by natural, large scale features. Other modes of climate variability include the Atlantic Multidecadal Oscillation, Northern Annular Mode, North Atlantic Oscillation, and more.

The PDO is frequently described as an extended El Niño -like pattern of Pacific climate.[3] The Pacific Ocean has a large impact on global weather climate. Research has shown when PDO is in a warm phase, global temperatures tend to increase, and when in a cool phase, global temperatures tend to decrease.[2] In the cool phase, cool waters wrap in a horseshoe shape around a core of warmer than average water. In the warm phase, this process is reversed.[2] See Figure 1 above for a visual representation of these temperature phases.

Figure 2. Warm and cold phase series of shifts in the Pacific Decadal Oscillation.[1]

Over the last hundred years, we have had only a handful of phase shifts.[2] Figure 2. Graphs these shifts in the Pacific Decadal Oscillation.

1905: switch to warm phase

1946: switch to cool phase

1977: switch to warm phase

2008: switch to cool phase



The PDO has a positive value when: sea surface temperatures are unusually cool in the interior North Pacific, warm along the Pacific Coast, and sea level pressures are below average over the North Pacific.[3] When the climate anomaly patterns are reversed, the PDO has a negative value: with warm sea surface temperature anomalies in the interior and cool sea surface temperature anomalies along the North American coast, or above average sea level pressures over the North Pacific.[3]

The PDO is highly correlated with sea surface temperature in the northern California Current (CC) area.[4] These phases result from the direction of winter winds in the North Pacific: winter winds blowing primarily from the southwest result in warmer conditions in the northern CC.[4] The CC warms at such times due to onshore transport of warm waters that normally lie offshore. Conversely, when winds blow primarily from the north, upwelling occurs both in the open ocean and at the coast, leading to cooler conditions in the northern CC.[4]

How PDO Impacts Climate

The change in location of the cold and warm water masses alters the path of the jet stream. The jet stream in the northern hemisphere delivers storms across the United States. The PDO phase that we appear to have entered will act to steer the jet stream further north over the Western Canada and The United States.[5]

For Further Reading

References

  1. ↑ 1.0 1.1 National Oceanic and Atmospheric Administration (2016). (Accessed July 9, 2026). Pacific Decadal Oscillation (PDO) [Online]. Available: https://psl.noaa.gov/pdo/
  2. ↑ 2.0 2.1 2.2 2.3 ”Pacific Decadal Oscillation (PDO)", Sealevel.jpl.nasa.gov. [Online]. Available: http://sealevel.jpl.nasa.gov/science/elninopdo/pdo/. [Accessed: 19- May- 2016].
  3. ↑ 3.0 3.1 3.2 "Pacific Decadal Oscillation (PDO) | Teleconnections | National Centers for Environmental Information (NCEI)", Ncdc.noaa.gov, 2016. [Online]. Available: https://www.ncdc.noaa.gov/teleconnections/pdo/. [Accessed: 19- May- 2016].
  4. ↑ 4.0 4.1 4.2 "Pacific Decadal Oscillation (PDO)", NOAA. [Online]. Available: https://www.nwfsc.noaa.gov/research/divisions/fe/estuarine/oeip/ca-pdo.cfm. [Accessed: 20- May- 2016].
  5. ↑ "Pacific Decadal Oscillation (PDO): Definition and Indices | NCAR - Climate Data Guide", Climatedataguide.ucar.edu. [Online]. Available: https://climatedataguide.ucar.edu/climate-data/pacific-decadal-oscillation-pdo-definition-and-indices. [Accessed: 23- May- 2016].
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