The planetary-scale waves that dictate our global weather and ocean currents

Nature · Published 18 October 2026 Swipe more like this →

In short: From the meanders of the jet stream to the deep ocean, Rossby waves act as Earth's great communicators. These massive undulations move heat and anomalies across entire basins, driving the very patterns that define our seasonal climates and daily weather.

Named after meteorologist Carl-Gustaf Arvid Rossby, these large-scale planetary waves arise from the variation of the Coriolis effect with latitude. In the atmosphere, they appear as giant meanders in high-altitude winds, specifically associated with the polar-front jet stream. These waves separate cold polar air from warm tropical air, facilitating heat transport between latitudes. When these atmospheric meanders become extreme, masses of air can detach to form cyclones and anticyclones, which are responsible for mid-latitude weather patterns.

In the ocean, Rossby waves govern the westward propagation of signals over timescales ranging from months to years. They can exist in barotropic forms, which are depth-uniform and propagate at faster speeds, or baroclinic forms, where density surfaces intersect pressure surfaces, causing the waves to vary vertically. These oceanic waves move along the thermoclinic boundary between warm upper layers and colder deep water. Their movement is influenced by interactions with mean currents, mesoscale eddies, and bottom topography.

Recent research has expanded our understanding of these dynamics beyond classical linear theory. New analysis of the potential vorticity equation suggests a nonlinear solitary solution under constant meridional shear. This model predicts that cyclonic and anticyclonic eddies emerge from negative and positive shear, respectively, with their centers tilting toward the poles or the equator. Furthermore, while the phase velocity of a Rossby wave always has a westward component, the group velocity—the movement of the wave set—can be eastward for shorter waves and westward for longer waves.

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