Atmospheric Teleconnections

Climate teleconnections are commonly defined as low-frequency variability in the atmosphere and oceans, while weather is defined as random high-frequency variability in the atmosphere. A secondary definition of teleconnections is that of significant correlations of climatological variables at widely separated points on the earth, showing evidence of preferred trough/ridge positions. These preferred modes of variability can be measured through the use of indices to quantify flow patterns associated with the teleconnection. The indices can then be correlated with climate variables across the globe that display significant relationships. Teleconnections can have periods ranging from several weeks to several decades and can affect temperature, precipitation, storm tracks, severe weather, and drought. The strength and coherence of a teleconnection’s signal often changes over time, and evidence suggests that the phase of the multidecadal ocean oscillations in the Atlantic and Pacific are often the cause. Extreme weather is often influenced by teleconnection patterns that cause persistent weather in various locations. Teleconnections are often a useful tool for seasonal forecasters and are commonly used in predicting commodity and energy trading markets. While many teleconnections were originally empirically derived, there has been progress in understanding the physical mechanisms behind many of them, which has helped to improve their predictability. There is much uncertainty regarding how climate change will affect many teleconnections, and this is an area of active research. The objective of this article is to introduce atmospheric and oceanic teleconnections that commonly affect weather patterns in the United States and around the globe. The article will introduce the history of how teleconnections were discovered and the statistics of how the index that determines the phase of the teleconnection was calculated. Several oceanic and atmospheric teleconnections will be discussed along with their known impacts on weather and climate.