Bibliothèque de Météo-France

Année de publication

2018

Résumé

Atmospheric blocking due to anomalous, persistent meandering of the jet stream often causes weather extremes in the midlatitudes. Despite its ubiquity, the onset mechanism of blocking is not well understood. Here we demonstrate with meteorological data that there exists a close analogy between blocking and traffic congestion on a highway, and that they 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 it 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.