The atmospheric circulation is well-known to exhibit substantial variability. This variability reflects weather patterns and circulation systems that occur on many time scales, lasting from a few days (characteristic of a normal storm system and frontal passage), to a few weeks (characteristic of a mid-winter warm-up or a mid-summer wet period) to a few months (characteristic of particularly cold winters or hot summers), to several years (characteristic of abnormal winters for several years in a row), to several centuries (characteristic of long-term climate change).

The term "teleconnection pattern" refers to a recurring and persistent, large-scale pattern of pressure and circulation anomalies that spans vast geographical areas. Teleconnection patterns are also referred to as preferred modes of low-frequency (or long time scale) variability. Although these patterns typically last for several weeks to several months, they can sometimes be prominent for several consecutive years, thus reflecting an important part of both the interannual and interdecadal variability of the atmospheric circulation. Many of the teleconnection patterns are also planetary-scale in nature, and span entire ocean basins and continents. For example, some patterns span the entire North Pacific basin, while others extend from eastern North America to central Europe. Still others cover nearly all of Eurasia.

All teleconnection patterns are a naturally occurring aspect of our chaotic atmospheric system, and can arise primarily a reflection of internal atmospheric dynamics. Additionally, some of these patterns, particularly those over the North Pacific, are also sometimes forced by changes in tropical sea-surface temperatures and tropical convection associated with both the ENSO cycle (Mo and Livezey 1986, Barnston and Livezey 1991) and the Madden-Julian Oscillation (MJO).

Teleconnection patterns reflect large-scale changes in the atmospheric wave and jet stream patterns, and influence temperature, rainfall, storm tracks, and jet stream location/ intensity over vast areas. Thus, they are often the culprit responsible for abnormal weather patterns occurring simultaneously over seemingly vast distances. For example, the 1995/986 winter was very cold and snowy over much of eastern North America, while northern Europe and Scandinavia were cold and southern Europe/ northern Africa experienced very wet and stormy conditions. These conditions were all partly related to the same teleconnection pattern: a strong negative phase of the North Atlantic Oscillation (NAO).

The Climate Prediction Center routinely monitors the primary teleconnection patterns and is involved in continuing research to better understand their role in the global climate system. Ten prominent teleconnection patterns can be identified in the Northern Hemisphere extratropics throughout the year, and all of these patterns have appeared previously in the meteorological literature (Barnston and Livezey 1987).

The following is a list of the prominent teleconnection patterns and their affected regions. Click on the desired pattern name for Discussion, Map and plotted historical Time series of that pattern.

Prominent patterns over the North Atlantic

North Atlantic Oscillation (NAO), exists in all months

East Atlantic Pattern (EA), exists in all months

Prominent patterns over Eurasia

East Atlantic/Western Russia pattern (EATL/WRUS), exists in all months

Scandinavia pattern (SCAND), exists in all months

Polar/Eurasia pattern , exists in all months

Prominent patterns over North Pacific/North America

West Pacific pattern (WP), exists in all months

East Pacific - North Pacific pattern (EP-NP), exists in all months

Pacific/North American pattern (PNA), exists in all months

Tropical/Northern Hemisphere pattern (TNH), during December-February

Pacific Transition pattern (PT),exists during August-September

Note that the East Atlantic/Western Russia pattern and the Scandinavia pattern are referred to by Barnston and Livezey (1987) as the Eurasia-2 and Eurasia-1 patterns, respectively.

Other Links:

Historical Archive of all Indices: Monthly Tabulated Indices for all teleconnection pattern amplitudes dating back to 1950.

Monthly Tabulated Indices: Last 12 months of indices for selected teleconnection patterns, as appears in the Climate Diagnostics Bulletin.

Monthly Plotted Time Series: Time series of pattern amplitudes for the last few years for selected teleconnection patterns, from the Climate Diagnostics Bulletin.

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