Diagrams illustrating Rossby waves traveling around the Sun and the Earth
Large-scale Rossby waves propagating around the Sun may play a role in triggering solar storms (yellow and deep red regions indicate where sunspot activity is unlikely and more likely, respectively). These waves are akin to Rossby waves in Earth’s atmosphere that influence weather, including potential heat waves (red arrows) and cold snaps (blue arrows). Credit: Simmi Sinha, University Corporation for Atmospheric Research
Source: Space Weather

Every so often, the Sun unleashes powerful bursts of plasma particles and magnetic field structures toward Earth. These solar storms can wreak havoc on power grids, satellites, and other infrastructure, but they are difficult to predict more than a few days in advance.

In a new review, Dikpati and McIntosh showcase mounting evidence that solar storms arise from solar Rossby waves, a type of wave associated with rotating fluids. Just as the 1939 discovery of Rossby waves in Earth’s atmosphere paved the way to accurate weather prediction, Rossby waves in the Sun could be key to predicting disruptive space weather in time to prepare for it.

On Earth, atmospheric Rossby waves arise from the planet’s rotation, and these large-scale meandering features help transport warm air toward the poles and cold air toward the tropics. Earth’s Rossby waves sometimes have extreme effects, such as those from 2019’s polar vortex.

Rossby waves in the solar plasma arise from the star’s rotation and originate within a transitional layer known as the tachocline. Unlike Earth’s Rossby waves, solar Rossby waves are strongly influenced by powerful magnetic fields. Recent observations and theoretical modeling suggest that these magnetically modified Rossby waves interact with the differing rates of rotation of the Sun’s plasma to trigger solar storms.

The researchers suggest that computational techniques developed for meteorology could inform strategies to improve solar storm predictions. In the future, scientists could use observations of the Sun’s surface as indicators of Rossby wave dynamics deep below, potentially revealing harbingers of solar storms weeks, months, or even a few years ahead of their eruption. (Space Weather, https://doi.org/10.1029/2018SW002109, 2020)

—Sarah Stanley, Freelance Writer


Stanley, S. (2020), Space weather forecasting takes inspiration from meteorology, Eos, 101, https://doi.org/10.1029/2020EO143927. Published on 11 May 2020.

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