Situated in Jupiter's southern hemisphere, the Great Red Spot is a massive, red-orange oval of high pressure over 10,000 miles wide. This anticyclone rotates counterclockwise with winds exceeding 200 miles per hour.

The Great Red Spot has been diminishing for nearly a century, with significant contraction in the last 50 years. While its latitudinal size remains stable, its longitudinal extent has decreased from 40 degrees in the late 19th century to 14 degrees in 2016, the year NASA's Juno spacecraft began its orbits around Jupiter.

"Many people have looked at the Great Red Spot over the last 200 years and were as fascinated by it as I am," said Caleb Keaveney, a Ph.D. student at Yale's Graduate School of Arts and Sciences and lead author of a new study in the journal Icarus. "A lot of those people were not professional astronomers - they were just passionate and curious. That, plus the curiosity I see in people when I talk about my work, makes me feel like part of something bigger than myself."

Despite extensive study, many aspects of the Great Red Spot remain mysterious. The exact time of its formation, the reasons behind its creation, and its distinct red color are still unknown.

Keaveney and his co-authors, Gary Lackmann of North Carolina State University and Timothy Dowling of the University of Louisville, investigated the impact of smaller, transient storms on the Great Red Spot. Using the Explicit Planetary Isentropic-Coordinate (EPIC) model developed by Dowling in the 1990s, they ran a series of 3D simulations.

The simulations, which included interactions between the Great Red Spot and smaller storms of varying frequency and intensity, indicated that the presence of other storms strengthened the Great Red Spot, causing it to grow larger. Control simulations without the smaller storms did not show the same strengthening effect.

"We found through numerical simulations that by feeding the Great Red Spot a diet of smaller storms, as has been known to occur on Jupiter, we could modulate its size," Keaveney said.

Their model drew parallels from Earth's atmosphere, where long-lived high-pressure systems, such as "heat domes" or "blocks," regularly occur. These systems are known to interact with smaller weather mechanisms, sustaining and amplifying extreme weather events like heat waves and droughts.

"Our study has compelling implications for weather events on Earth," Keaveney said. "Interactions with nearby weather systems have been shown to sustain and amplify heat domes, which motivated our hypothesis that similar interactions on Jupiter could sustain the Great Red Spot. In validating that hypothesis, we provide additional support to this understanding of heat domes on Earth."

Further modeling is expected to refine these findings and possibly provide more insights into the Great Red Spot's initial formation.

The research received funding from a North Carolina Space Grant and support from the Astronaut Scholarship Foundation and the Goldwater Scholarship Foundation. It was conducted as an undergraduate research project in the Department of Marine, Earth, and Atmospheric Sciences at North Carolina State University.

Research Report:Effect of transient vortex interactions on the size and strength of Jupiter's Great Red Spot

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