The Great Red Spot on Jupiter – the largest storm in the solar system – has been shrinking for most of the last century, particularly in the last 50 years.
A new study by American scientists may help explain why the Great Red Spot on Jupiter – the largest storm in the Solar System – is gradually diminishing.
Located in the southern hemisphere of Jupiter, the Great Red Spot is an oval-shaped red-orange swirl with high pressure, measuring over 16,000 km wide. Winds here continuously blow at speeds exceeding 320 km/h in a counterclockwise direction, hence referred to as a cyclone.
The Great Red Spot has been shrinking for most of the last century, especially in the last 50 years. Although its latitudinal width has remained relatively stable, its longitudinal length has decreased from 40 degrees at the end of the 19th century to just 14 degrees in 2016, when NASA’s Juno spacecraft arrived at Jupiter to conduct a series of orbits around the planet.
The Great Red Spot on Jupiter changing size. (Source: phys)
“Many people have observed the Great Red Spot for the past 200 years and are as fascinated as I am,” said Caleb Keaveney, a PhD candidate at Yale University’s Graduate School of Arts and Sciences and the lead author of the new study published in the journal Icarus.
“Many of them are not professional astronomers – they are simply passionate and curious. That, along with the curiosity I see in people when I talk about my work, makes me feel like I’m part of something greater than myself.”
Part of the curiosity surrounding the Great Red Spot stems from the mysteries that surround it, despite extensive research. Astronomers do not know exactly when this red spot formed, why it formed, or even why it is red.
In this study, Keaveney, from Yale’s Department of Earth and Planetary Sciences, along with co-authors Gary Lackmann from the University of North Carolina and Timothy Dowling from the University of Louisville, focused on the influence of smaller, temporary storms on the Great Red Spot.
The researchers conducted a series of 3D simulations of the red spot using the EPIC model (Explicit Planetary Isentropic-Coordinate), a planetary atmospheric model developed by Dowling in the 1990s.
Some simulations involved interactions between the Great Red Spot and smaller storms with varying frequencies and intensities, while another set of control simulations excluded the smaller storms.
Comparing the simulations showed that the presence of other storms reinforced the Great Red Spot, causing it to grow larger.
“Through numerical simulations, we found that by providing the Great Red Spot with ‘food’ in the form of smaller storms, as is known to occur on Jupiter, we can adjust its size,” Keaveney said.
The researchers based their model on long-lasting high-pressure systems observed right in Earth’s atmosphere. These systems – known as “heat domes” or “air masses” – frequently occur in the westerly jet streams circulating at mid-latitudes on Earth and play a crucial role in extreme weather phenomena such as heatwaves and droughts. The longevity of these “air masses” is related to their interaction with temporary and smaller weather mechanisms, including high-pressure cyclones and anticyclones.
“Our research has intriguing implications for weather phenomena on Earth,” Keaveney stated. “The interaction with neighboring weather systems has been shown to sustain and amplify heat domes, which supports our hypothesis that similar interactions on Jupiter could sustain the Great Red Spot. By confirming that hypothesis, we provide further support for this understanding of heat domes on Earth.”
Keaveney noted that future modeling steps will allow researchers to refine their new findings – and possibly shed light on the initial formation of the Great Red Spot.
