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What drives the weather system on Earth?
The answer is that time on Earth is mainly determined by processes in a thin layer of the atmosphere near the surface of the planet. A similar consideration of the weather system has been applied to other planets such as Jupiter and Saturn.
However, a new study by a trio of scientists has shown that this hypothesis was wrong.
The scientists, two with Harvard University and the other with the University of Alberta, have found evidence that time on Saturn and Jupiter can be driven by forces that are vastly different from time on Earth. Using computer simulations, scientists showed that Jupiter and Saturn’s weather systems could be driven by internal rather than external forces, resulting in the formation of large anticyclones like Jupiter’s famous red spot.
For the study, the scientists created two simulations to mimic the conditions on Jupiter and Saturn. Instead of assuming the previous hypothesis, weather models are driven by turbulence just above the surface; the scientists programmed their simulations to consider the turbulent convection that occurs in spherical shells as they rotate.
In one of the simulations, also known as the thin-shell approach, the simulation was used to reproduce what happens with the convection layers on gas giants such as Saturn and Jupiter – the events they notice have very little interaction with the planet’s magnetic field. They found that the simulation showed cyclones, zonal jets, and anticyclones forming spontaneously on Jupiter and Saturn.
Another simulation, also called the “thick shell” approach, was programmed to mimic the interactions between the planet’s internal dynamo and the outer hydrodynamic layer. It showed plumes ejected from the magnetic layer, giving rise to what they describe as pancake-shaped weather patterns near the surface.
Scientists have suggested that some of the weather patterns on both planets are likely driven by jet streams and sub-surface processes. They also recommend that their reproductions show that the well-known red spot may have molded itself when the planet’s dynamo region triggered processes that led to the production of large anticyclones in the atmosphere.
Journal reference:
- Rakesh Kumar Yadav et al. Convection-Driven Deep Vortex Formation on Jupiter and Saturn, Science Advances (2020). DOI: 10.1126 / sciadv.abb9298
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