The Pacific Ocean is the largest single climate balancing engine. As the single largest ocean in both size and volume, the Pacific is the most powerful climate control mechanism. “all other oceans can fit into the Pacific”.
Key long term climate engine:
Pacific Interdecadal Oscillation
The PIO/PDO is in simple terms a long term oscillation pattern in the Pacific Oceans circulation that is effectively a long term version of the ENSO patterns of LaNina and ElNino. In the North Pacific, the atmosphere and the ocean display a trend of co-variance with a period of about 20 years.
Supposing that SSTs (Sea Surface Temperatures) are lower than their normals in the central part of the North Pacific, they are likely to be higher than their normals both in the eastern part of the North Pacific and in the equatorial Pacific. This seesaw pattern varies slowly, and appears repeatedly with a period of about 20 years. In this case, the Aleutian Low and the jet stream in the upper troposphere tend to be strong. The North Pacific Index (NPI) is utilized as an indicator for the strength of the Aleutian Low.
As described above, ocean-atmosphere coupling causes decadal oscillation in the North Pacific. Although some hypotheses have been proposed tp elucidate the mechanism behind the PDO, it is not yet fully understood.
Positive PIO – The Positive Phase of the PIO is effectively a long term version of the El Nino patter that increases rainfall in parts of the USA and creates droughts in Australia and Indonesia.
The positive phase aligns often with a warming trend in global temperatures.
Negative PIO – The negative phase of the PIO is the reverse of the positive phase and creates a long term lasting version of the La Nina pattern that decreases rainfall in parts of the USA and increases rainfall for Eastern Australia and Indonesia.
The negative phase aligns often with a cooling trend in global temperatures.
Current PDO Status
PDO History since 1900
The Asia Blob
Many weather and climate changes are being created by concentrations of pollution being generated by China, India, Japan, Vietnam, Thailand and other Asian nations that make their way into the Western Pacific north of Papua New Guinea.
This region is a transfer location for the ocean conveyer belt, which can
ENSO is one of the most important climate phenomena on Earth due to its ability to change the global atmospheric circulation, which in turn, influences temperature and precipitation across the globe. We place great importance on ENSO because we can often predict its arrival many seasons in advance of its strongest impacts on weather and climate.
Though ENSO is a single climate phenomenon, it has three states, or phases, it can be in. The two opposite phases, “El Niño” and “La Niña,” require certain changes in both the ocean and the atmosphere because ENSO is a coupled climate phenomenon. “Neutral” is in the middle of the continuum.
- El Niño: A warming of the ocean surface, or above-average sea surface temperatures (SST), in the central and eastern tropical Pacific Ocean. Over Indonesia, rainfall tends to become reduced while rainfall increases over the tropical Pacific Ocean. The low-level surface winds, which normally blow from east to west along the equator (“easterly winds”), instead weaken or, in some cases, start blowing the other direction (from west to east or “westerly winds”).
- La Niña: A cooling of the ocean surface, or below-average sea surface temperatures (SST), in the central and eastern tropical Pacific Ocean. Over Indonesia, rainfall tends to increase while rainfall decreases over the central tropical Pacific Ocean. The normal easterly winds along the equator become even stronger.
- Neutral: Neither El Niño or La Niña. Often tropical Pacific SSTs are generally close to average. However, there are some instances when the ocean can look like it is in an El Niño or La Niña state, but the atmosphere is not playing along (or vice versa).
The following are other components that link to the ENSO drivers.
The La Niña Outgoing Longwave Radiation (OLR) index tabulates synoptic-scale breaks in deep-atmospheric convection activity over the western tropical Pacific. Over the time for which satellite-based OLR information has been available, the La Niña events distinguished by their OLR behavior (the index’s large peaks in the Annual Integral figure) have predominantly accounted for the familiar La Niña weather associations over North America (Chiodi and Harrison 2015a). The convection breaks tabulated by the index are associated with near-surface easterly wind surges that drive La Niña type sea surface temperature anomaly patterns when they occur in sufficient numbers over the tropical Pacific (Chiodi and Harrison 2015b)
The El Niño outgoing longwave radiation (OLR) index is an indicator of eastern-central tropical Pacific deep-atmospheric convection conditions. It is calculated with OLR anomalies in the box 160°W – 110°W, 5°S – 5°N.
Over the time for which satellite-based OLR information has been available, the El Niño events distinguished by their OLR behavior (the index’s large negative peaks) have predominantly accounted for the familiar El Niño weather associations over North America (Chiodi and Harrison 2013, 2015).
Southern Oscillation Index (SOI) The SOI index is the normalized difference in pressure between Darwin, Australia and Tahiti. It is associated with El Niño and La Niña phases of ENSO.
In the shorter series case, monthly averages are shown by the plus signs and 3-month running mean filtered index values are shown by the shaded regions. In the longer series case, 3-month averages are shown by the plus signs and 12-month running mean filtered index values are shown by the shaded regions.
Pacific-North American Pattern (PNA)
The PNA index indicates the predominance of a characteristic pattern of atmospheric circulation and teleconnection over the North Pacific and North America.
In the shorter series case, monthly averages are shown by the plus signs and 3-month running mean filtered index values are shown by the shaded regions. In the longer series case, 3-month averages are shown by the plus signs and 12-month running mean filtered index values are shown by the shaded regions. The monthly standard deviation of the index over the period 1948-2005 is indicated on each plot.