New model explaining why Jupiter's mysterious Great Red Spot has not disappeared

Nov 14, 2013
This is Jupiter's Great Red Spot in 2000 as seen by NASA's Cassini orbiter. Credit: NASA/JPL/Space Science Institute

Jupiter's Great Red Spot is one of the solar system's most mysterious landmarks. Based on what scientists understand about fluid dynamics, this massive storm – which is big enough to engulf the Earth two or three times over – should have disappeared centuries ago.

Pedram Hassanzadeh, a postdoctoral fellow at Harvard University, and Philip Marcus, a professor of at the University of California, Berkeley, think they can explain why. Their work, which Hassanzadeh will present at the annual meeting of the American Physical Society's Division of Fluid Dynamics in Pittsburgh on November 25, also provides insight into persistent ocean eddies and vortices that contribute to star and planet formation.

"Based on current theories, the Great Red Spot should have disappeared after several decades. Instead, it has been there for hundreds of years," said Hassanzadeh, who is a post-doctoral fellow at Harvard's Center for the Environment and the Department of Earth and Planetary Sciences.

Many processes dissipate vortices like the Red Spot, Hassanzadeh explained. The turbulence and waves in and around the Red Spot sap the energy of its winds. The also loses energy by radiating heat. Finally, the Red Spot sits between two strong jet streams that flow in opposite directions and may slow down its spinning.

Some researchers argue that the Red Spot gains energy by absorbing smaller vortices. "Some computer models show that large vortices would live longer if they merge with smaller vortices, but this does not happen often enough to explain the Red Spot's longevity," Marcus said.

To probe the mystery of the Red Spot's survival, Hassanzadeh and Marcus built a model of their own. It differed from existing models because it was fully three dimensional and had very high resolution. Many vortex models focus on the swirling horizontal winds, where most of the energy resides. Vortices also have vertical flows, but these have much less energy.

"In the past, researchers either ignored the vertical flow because they thought it was not important, or they used simpler equations because it was so difficult to model," Hassanzadeh said.

Yet the vertical motion turns out to hold the key to the Red Spot's persistence. As the vortex loses energy, the vertical flow transports hot gases from above and cold gases from below the vortex toward its center, restoring part of its lost energy.

The model also predicts a radial flow, which sucks winds from the high-speed jet streams toward the vortex center. This pumps energy into the vortex, enabling it to last longer.

According to Hassanzadeh, the same vertical flow could explain why oceanic vortices, such as those formed near the Straits of Gibraltar, can last for years in the Atlantic Ocean. Their vertical flow plays a role in the ocean ecosystem by lifting nutrients to the surface.

Vortices may also midwife the formation of stars and planets, lasting for millions of years as they pull interstellar dust and rocks into large masses.

Hassanzadeh and Marcus know their model does not entirely explain the Red Spot's long life span. They believe the occasional absorption of smaller vortices, consistent with observation, may provide the extra needed for hundreds of years of life. They have begun modifying their computer model to test this thesis.

Perhaps, one day, Jupiter's Great Red Spot will seem a little less mysterious.

Explore further: Stingray movement could inspire the next generation of submarines

More information: The presentation "On the Unexpected Longevity of the Great Red Spot, Oceanic Eddies, and other Baroclinic Vortices," is at 3:48 p.m. on Monday, November 25, 2013 in the David L. Lawrence Convention Center, Room 403. ABSTRACT: meeting.aps.org/Meeting/DFD13/Event/203662

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Lurker2358
1 / 5 (18) Nov 14, 2013
"In the past, researchers either ignored the vertical flow because they thought it was not important, or they used simpler equations because it was so difficult to model," Hassanzadeh said.


You mean sort of like how galaxy models and galaxy merger models don't actually do the correct N-body equation, but just "fudge" it?
Zephir_fan
Nov 14, 2013
This comment has been removed by a moderator.
Feldagast
1.8 / 5 (15) Nov 14, 2013
Must be global warming.
cantdrive85
1 / 5 (19) Nov 14, 2013
"Based on current theories, the Great Red Spot should have disappeared after several decades. Instead, it has been there for hundreds of years,"

Based on theories of fluid dynamics, unfortunately Jupiter's "plasma does not " understand ", how beautiful the theories are and absolutely refuses to obey them."
Zephir_fan
Nov 14, 2013
This comment has been removed by a moderator.
Zephir_fan
Nov 14, 2013
This comment has been removed by a moderator.
triplehelix
1 / 5 (14) Nov 15, 2013
"In the past, researchers either ignored the vertical flow because they thought it was not important, or they used simpler equations because it was so difficult to model," Hassanzadeh said.


Kind of like how Climate models are built ignoring many variables or not knowing many variables and thinking they know the answer.

I understand Science is a continous learning curve. But if you have a theory that is disproved by observation, then guess what, you need a new theory, or a highly modified one.

Bugs me when science writers say "This goes against our theories". It's the other way around...
Lurker2358
1 / 5 (14) Nov 15, 2013
You mean sort of like how galaxy models and galaxy merger models don't actually do the correct N-body equation, but just "fudge" it?


Well why don't you do the N-body equation (whatever that is, do you know?) for us and really show them up. Does the N-body equation have anything to do with the AWT?


N-body is the solution for the orbital behavior/parameters of a system of N objects, given their known position and velocity.

A galaxy cannot be properly modeled because there are too many objects, and the number of vectors that must be calculated and summed is N^2. No computer can do the math, even in years.

Using round numbers, If you have 200 billion stars in a galaxy you have to calculate 40,000,000,000,000,000,000,000 unique vectors, and 200 billion vector sums of those vectors, each vector sum containing 200 billion terms....repeating continually.

Therefore galaxy models and galaxy merger models are wrong. They aren't just a little wrong, they are terrible.
triplehelix
1 / 5 (12) Nov 15, 2013
Using round numbers, If you have 200 billion stars in a galaxy you have to calculate 40,000,000,000,000,000,000,000 unique vectors, and 200 billion vector sums of those vectors, each vector sum containing 200 billion terms....repeating continually.


I have always wondered this. When you have two particles in a theoretical box, you can count the two vectors and they'll affect each other. You can then simultaneously see the effect. Add a 3rd, and that 3rd particle has an affect on 1st and 2nd, and with themselves. Add a 4th. Add a 5th, then a 6th. How do you get a signal vs noise smoothness to know what particle is doing what exactly? I can see general maths being applied for statistical averages. But like you say, to get EXACT, or NEAR EXACT figures on billions of stars containing trillions of moving bodies, all having major/minor effects...Cluster fuck.
Lurker2358
1 / 5 (14) Nov 15, 2013
It gets even worse.

Because Gravity is so weak over large distances, and you're talking about light years distance, you need each vector to be precise to about a 1nm/s^2 for the acceleration vectors, otherwise the error will still be too large and produce bogus results after a relatively short amount of time being modeled. As in, within a couple years an object can start to fly off in the wrong direction.

If you are off by one billionth of a metter per second in acceleration, then after 1 year the object is moving at a velocty that is off by 3cm per second. Not a big deal right? But you are modeling time scales of a billion years.

3cm/yr acceleration error * 1 billion years = 315 km/s error in velocity*.

* could show up as a scalar, or a wrong direction, but usually some combination of the two.

This also doesn't take into account secondary errors from changes in gravity due to the object no longer being the same distance it should be, etc.
Lurker2358
1 / 5 (13) Nov 15, 2013
After 1 billion years, that objects average velocity error is 157.5 km/s.

After 1 billion years averaging that large of a velocity error, the calculated position of the object can be wrong by as much as 525,000 LIGHT YEARS, or roughly 5 Galactic Diameters, or 10 Galactic Radii.

That is from a 1 nano-meter per second error in the acceleration vector calculation.
Zephir_fan
Nov 15, 2013
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tadchem
1.4 / 5 (11) Nov 15, 2013
Calling the Great Red Spot a 'landmark' seems a bit of a stretch...
Mimath224
1 / 5 (9) Nov 18, 2013
Not sure about my thoughts on this but isn't it so that most real vortices end up eventually as irrotational and shortening the life of a vortex? But would this not be seen by the different v's? The GRS on Jupiter would seem to have a vector that maintains the rotational vortex.

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