Research Article

Atmospheric blocking as a traffic jam in the jet stream

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Science  06 Jul 2018:
Vol. 361, Issue 6397, pp. 42-47
DOI: 10.1126/science.aat0721

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A traffic jam of air

Persistent meandering of the jet stream can cause atmospheric blocking of prevailing eastward winds and result in weather extremes such as heat waves in the midlatitudes. Nakamura and Huang interpret the poorly understood origins of these systems as the meteorological equivalents of traffic congestion on a highway and show how they can be described by analogous mathematical theory. Climate change may affect the frequency of blocking as well as its geographic distribution, reflecting a simultaneous shift in the structure of the stationary atmospheric waves and the regional capacity of the jet stream.

Science, this issue p. 42

Abstract

Atmospheric blocking due to anomalous, persistent meandering of the jet stream often causes weather extremes in the mid-latitudes. Despite the ubiquity of blocking, the onset mechanism is not well understood. Here we demonstrate a close analogy between blocking and traffic congestion on a highway by using meteorological data and show that blocking and traffic congestion can be described by a common mathematical theory. The theory predicts that the jet stream has a capacity for the flux of wave activity (a measure of meandering), just as the highway has traffic capacity, and when the capacity is exceeded, blocking manifests as congestion. Stationary waves modulate the jet stream’s capacity for transient waves and localize block formation. Climate change likely affects blocking frequency by modifying the jet stream’s proximity to capacity.

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