Geoscience Reference
In-Depth Information
Table 2.1 Major oscillations
Southern Oscillation (SO)
A strongly anti-correlated pressure anomaly over the Indian and South Pacific Oceans. It has a
slightly variable period averaging 2.33 years and is often analyzed as part of an ENSO event.
North Atlantic Oscillation (NAO)
Reflects pressure variations and the stability of the Icelandic Low and the Azores-Bermuda High
pressure cells. The NAO has a marked influence upon the climates of western Europe.
North Pacific Oscillation (NPO)/Pacific Decadal Oscillation (PDO)
A long-lived phenomenon defined by surface ocean temperatures in the northeast and tropical Pacific Ocean.
Madden-Julian Oscillation (MJO)
An eastward progression of tropical rainfall, which produces anomalous rainfall patterns that may be
enhanced or suppressed.
Quasi-biennial Oscillation (QBO)
A low-latitude oscillation that is longer than the dominant annual cycle and results in a periodic reversal
of winds in the lower stratosphere.
Pacific North American Oscillation (PNA)
An alternating pattern between pressures in the central Pacific Ocean and centers of action over
western Canada and the southeastern United States.
Arctic Oscillation (AO)
An oscillation in which atmospheric pressure, at polar and mid-latitude locations, fluctuates between
defined positive and negative phases.
Antarctic Oscillation (AAO)
An oscillation in values of mid- and high-latitude surface pressure systems in the Southern
Hemisphere. It is quantified by the Antarctic Oscillation Index.
Teleconnections play an integral part in the study of air-sea interactions and
global climate processes. They often provide the missing piece in the under-
standing of climate patterns, both spatial and temporal, that occur across the
world. The identification of connections suggested by teleconnections has
become so important that the study forms a subfield of the atmospheric sciences.
Table 2.2 provides examples of some teleconnections between two regions.
The study of teleconnections is largely based upon statistical analysis and
requires reliable data sources. Of particular importance is the use of empirical
orthogonal functions, the EOFs, or the principal components. Using grid point
pressure values as a matrix, principal components, eigenvalues and eigenvectors
are obtained from the analysis. Through the manipulation of these data, a set of
component scores is derived and these can be clustered to form a classification
used to identify the patterns under investigation. The analysis is, of course,
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