'Hot spots' ride a merry-go-round on Jupiter

Mar 14, 2013 by Jia-Rui Cook
The dark hot spot in this false-color image from NASA's Cassini spacecraft is a window deep into Jupiter's atmosphere. Credit: NASA/JPL-Caltech/SSI/GSFC

(Phys.org) —In the swirling canopy of Jupiter's atmosphere, cloudless patches are so exceptional that the big ones get the special name "hot spots." Exactly how these clearings form and why they're only found near the planet's equator have long been mysteries. Now, using images from NASA's Cassini spacecraft, scientists have found new evidence that hot spots in Jupiter's atmosphere are created by a Rossby wave, a pattern also seen in Earth's atmosphere and oceans. The team found the wave responsible for the hot spots glides up and down through layers of the atmosphere like a carousel horse on a merry-go-round.

"This is the first time anybody has closely tracked the shape of multiple hot spots over a period of time, which is the best way to appreciate the dynamic nature of these features," said the study's lead author, David Choi, a NASA Postdoctoral Fellow working at NASA's Goddard Space Flight Center in Greenbelt, Md. The paper is published online in the April issue of the journal Icarus.

Choi and his colleagues made time-lapse movies from hundreds of observations taken by Cassini during its flyby of Jupiter in late 2000, when the spacecraft made its closest approach to the planet. The movies zoom in on a line of hot spots between one of Jupiter's dark belts and bright white zones, roughly 7 degrees north of the equator. Covering about two months (in Earth time), the study examines the daily and weekly changes in the sizes and shapes of the hot spots, each of which covers more area than North America, on average.

Much of what scientists know about hot spots came from NASA's , which released an atmospheric probe that descended into a hot spot in 1995. This was the first, and so far only, in-situ investigation of Jupiter's atmosphere.

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NASA postdoctoral fellow David Choi discusses his study of dark features in Jupiter's atmosphere called "hot spots," and their connection to large-scale atmospheric waves. Credit: NASA SVS

"Galileo's probe data and a handful of orbiter images hinted at the complex winds swirling around and through these hot spots, and raised questions about whether they fundamentally were waves, cyclones or something in between," said Ashwin Vasavada, a paper co-author who is based at NASA's Jet Propulsion Laboratory in Pasadena, Calif., and who was a member of the Cassini imaging team during the Jupiter flyby. "Cassini's fantastic movies now show the entire life cycle and evolution of hot spots in great detail."

Because hot spots are breaks in the clouds, they provide windows into a normally unseen layer of Jupiter's atmosphere, possibly all the way down to the level where water clouds can form. In pictures, hot spots appear shadowy, but because the deeper layers are warmer, hot spots are very bright at the infrared wavelengths where heat is sensed; in fact, this is how they got their name.

In this series of images from NASA's Cassini spacecraft, a dark, rectangular hot spot (top) interacts with a line of vortices that approaches from on the upper-right side (second panel). The interaction distorts the shape of the hot spot (third panel), leaving it diminished (bottom). Credit: NASA/JPL-Caltech/SSI/GSFC

One hypothesis is that hot spots occur when big drafts of air sink in the atmosphere and get heated or dried out in the process. But the surprising regularity of hot spots has led some researchers to suspect there is an atmospheric wave involved. Typically, eight to 10 hot spots line up, roughly evenly spaced, with dense white plumes of cloud in between. This pattern could be explained by a wave that pushes cold air down, breaking up any clouds, and then carries warm air up, causing the heavy cloud cover seen in the plumes. Computer modeling has strengthened this line of reasoning.

From the Cassini movies, the researchers mapped the winds in and around each hot spot and plume, and examined interactions with vortices that pass by, in addition to wind gyres, or spiraling vortices, that merge with the hot spots. To separate these motions from the jet stream in which the hot spots reside, the scientists also tracked the movements of small "scooter" clouds, similar to cirrus clouds on Earth. This provided what may be the first direct measurement of the true wind speed of the jet stream, which was clocked at about 300 to 450 mph (500 to 720 kilometers per hour)—much faster than anyone previously thought. The hot spots amble at the more leisurely pace of about 225 mph (362 kilometers per hour).

By teasing out these individual movements, the researchers saw that the motions of the hot spots fit the pattern of a Rossby wave in the atmosphere. On Earth, Rossby waves play a major role in weather. For example, when a blast of frigid Arctic air suddenly dips down and freezes Florida's crops, a Rossby wave is interacting with the polar jet stream and sending it off its typical course. The wave travels around our planet but periodically wanders north and south as it goes.

The wave responsible for the hot spots also circles the planet west to east, but instead of wandering north and south, it glides up and down in the atmosphere. The researchers estimate this wave may rise and fall 15 to 30 miles (24 to 50 kilometers) in altitude.

The new findings should help researchers understand how well the observations returned by the Galileo probe extend to the rest of Jupiter's atmosphere. "And that is another step in answering more of the questions that still surround on Jupiter," said Choi.

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rubberman
5 / 5 (3) Mar 15, 2013
One day our tech will be able to penetrate deep into the jovian atmosphere in the form of a probe that can last long enough to map the layers for composition and wind speed, and possibly reach the layer where fluid dynamics are the key player. I hope I am still alive when we find out how the various layers organize themselves and the exotic forces at work there.
Q-Star
4.4 / 5 (7) Mar 15, 2013
and possibly reach the layer where fluid dynamics are the key player.


In almost all atmospheric weather systems, from the rarest to the most dense, fluid dynamics with thermodynamics are the key players. But it would be great to be able to make direct measurements of the super dense conditions at lower altitudes.
cantdrive85
1 / 5 (5) Mar 15, 2013
fluid dynamics with thermodynamics are the key players.

And here I thought you didn't have a favorite, but point to these as "key players". So are you suggesting that in certain circumstances that particular forces may have a more determinate factor than others? Weird! Kinda like how a plasma adheres to the forces of EM while gravity is almost a non factor? BTW, how do those key players describe the 400Km winds of Jupiter, or the 2000 Km winds on Neptune? Right, they fail miserably. Some other source of energy is required.

I hope I am still alive when we find out how the various layers organize themselves and the exotic forces at work there.

I would postulate that the various plasma double layers of Jupiter (and others) organize themselves like onion skins, just as they do on the Sun and Earth. There are unlikely any "exotic" forces at work there, just overlooked forces.
Q-Star
3.9 / 5 (7) Mar 15, 2013
And here I thought you didn't have a favorite, but point to these as "key players".


So applying the appropriate weight means "having a favorite". No wonder this stuff is so difficult for ya.

So are you suggesting that in certain circumstances that particular forces may have a more determinate factor than others?


Of course that is what I am suggesting. Does current flow more readily in some substances than others? Does gravity impart more weight on the earth than on the moon? Does heat transfer more readily through some substances than others?

Weird!


I can see why ya would think so. But it is a big universe filled with many wonders.

There are unlikely any "exotic" forces at work there, just overlooked forces.


I agree, unlikely any "exotic" forces at work, probably the same ones we're all (except those who think there is nothing but plasma) used to working with, but working in "exotic" environments.
cantdrive85
1 / 5 (2) Mar 15, 2013
So applying the appropriate weight means "having a favorite".

This has been my point all along, applying the "appropriate weight" of how EM (39 orders of magnitude more powerful than gravity) affects plasma. Obviously lost on you.

Of course that is what I am suggesting.

Everywhere except where there is plasma (99.99% of the universe), correct?
Q-Star
3.4 / 5 (5) Mar 15, 2013
So applying the appropriate weight means "having a favorite".

This has been my point all along, applying the "appropriate weight" of how EM (39 orders of magnitude more powerful than gravity) affects plasma. Obviously lost on you.

Of course that is what I am suggesting.

Everywhere except where there is plasma (99.99% of the universe), correct?


Ya don't know how to use "plasma physics" yourself, and ya suggest that I don't? Wow, I'm hurt.

Ya couldn't even write a high school term paper on "plasma physics" or "electromagnetics", why would anything ya say here be considered seriously.

All ya have ever done here is parrot one-liners, 40 year old quotes, and provide lists of links (in which many of the papers contradict your position) to papers ya haven't read, or read incorrectly. Zephyr knows more physics than ya do, and that is no exaggeration. Ya are a parrot-troll, at least Zephyr attempts to think out the problem at hand (in his own weird way.)

cantdrive85
1 / 5 (3) Mar 15, 2013
Hot gas! BTW, still waiting for you to point me in the direction of the astrophysical text that describes how charged particles are accelerated in plasma double layers or how exploding double layers affect certain phenomenon. Right, it doesn't exist!
Q-Star
3.4 / 5 (5) Mar 15, 2013
Hot gas! BTW, still waiting for you to point me in the direction of the astrophysical text that describes how charged particles are accelerated in plasma double layers or how exploding double layers affect certain phenomenon. Right, it doesn't exist!


Not that there is a chance ya would ever read them, or even one.

Here's a list to get ya started.

Astrophysics for Physicists - Choudhuri, Arnab Rai - (2010)

Astrophysics Processes - Bradt, Hale - (2008)

An Introduction to Modern Astrophysics 2nd ed - B. Carrol, D. Ostlie (2007)

Physics and Chemistry of the Solar System 2nd ed - J. Lewis (2004)

Astrophysical Concepts 4e - Harwit (2006)

Astrophysics_A New Approach-Kundt, Wolfgang - (2005)

The Road to Galaxy Formation (2007)

Galaxy Formation & Evolution - Spinrad - (2005)

The Origin and Dynamics of Solar Magnetism - Thompson -(2009)

Solar Astrophysics 2nd ed - P. Foukal (2004)

But ya really aren't ready for this level yet.
Q-Star
3.4 / 5 (5) Mar 15, 2013
@ cantdrive

Now if ya are looking for a astrophysics text that says some of the uneducated and uninformed things ya parrot,,, then no I don't have one on my shelf. If the list above is not enough to keep ya busy, if ya might be some sort of speed reading genius with an eidetic memory, let me know, I have dozens and dozens of others that I could list for ya.
cantdrive85
1 / 5 (2) Mar 15, 2013
Wow, thank you again for so concisely proving Alfven's POV of an ignorance among the astrophysicists. I chose 'The Origin and Dynamics of Solar Magnetism'-Thompson (2009). We'll just take a snippet or two from the first couple of pages.

In the abstract (at least he's honest),
"Fundamental difficulties with the concept of turbulent diffusion of magnetic fields suggests that the solar dynamo problem needs to be reformulated."

Anyone worth their salt should know that "turbulent diffusion" does not create magnetic fields, only electric currents do so, and this is why the problem needs to be "reformulated". Apparently this author didn't get to that level in EM.
Q-Star
3.7 / 5 (6) Mar 15, 2013
Wow, thank you again for so concisely proving Alfven's POV of an ignorance among the astrophysicists. I chose 'The Origin and Dynamics of Solar Magnetism'-Thompson (2009). We'll just take a snippet or two from the first couple of pages.

In the abstract (at least he's honest),
"Fundamental difficulties with the concept of turbulent diffusion of magnetic fields suggests that the solar dynamo problem needs to be reformulated."

Anyone worth their salt should know that "turbulent diffusion" does not create magnetic fields, only electric currents do so, and this is why the problem needs to be "reformulated". Apparently this author didn't get to that level in EM.


I see ya either:

1) Have a severe reading comprehesion problem.
OR
2) Are so dishonest that ya would pretend that a writer is writing something other than what he writing so as to make the writer wrong.
OR
3) Ya have know idea what the writer was saying.

I vote for all of the above. Case proven. Case closed.
Q-Star
3.7 / 5 (6) Mar 15, 2013
@ cantdrive,,, is this guy ignoring your precious electricity or magnetism? You picked a few words, when what he said was

Eugene Parker (2008)"We review some longstanding scientific mysteries related to solar magnetism, with final attention to the mystery of the "turbulent diffusion" essential for the theoretical
αω-dynamo that is believed to be the source of the magnetic fields of the Sun. Fundamental difficulties with the concept of turbulent diffusion of magnetic fields suggest that the solar
dynamo problem needs to be reformulated. An alternative dynamo model is proposed, but it remains to be shown that the model can provide the quantitative aspects of the cyclic magnetic fields of the Sun."

Sounds like an astrophysicist doing the ignore thing, right?
Q-Star
3.7 / 5 (6) Mar 15, 2013
@ cantdrive: Here ignoring your precious electricity and magnetism on the next page.

Parker (2008) "We possess a vast archive of observations on the magnetic field at the visible surface of the Sun, providing boundary conditions for the origin of the field but giving no clear picture of the magnetic fields below the surface, concerning which we have many questions. There has been substantial progress in modeling various forms of the presumed αω-dynamo (combining the effects of the cyclonic convection and the nonuniform rotation)responsible for the 22-year magnetic cycle of the Sun, giving some idea of the available theoretical possibilities. "

Astrophysicists never have anything to say about electricity or magnetism?

Since the entire book, and every author continues in the same vein,,, Would like to try another from that list. (As if anyone needed any more proof that ya are an idiot when it comes to astrophysics in general, and the state of astrophysical instruction in particular.
cantdrive85
1 / 5 (4) Mar 15, 2013

He goes on...
What causes the subsurface convection to sweep thousands of magnetic fibrils together and then compress them into two or more kilogauss.

First of all, there are no "magnetic fibrils" or "field lines", they are not physical things. It is a magnetic field in which the physical things, plasma, are arranged by the physical laws thereof. The "magnetic fibrils" are in fact the currents, and it is those currents which are creating the magnetic field which is pinching the current, these are well understood plasma concepts.

It's not about merely mentioning some effect(magnetism, electricity, etc..), it's also about understanding the phenomenon. By calling the current a "magnetic fibril" shows a distinct ignorance of the observation. Obviously magnetism isn't ignored by astrophysicists, mainly because it is unavoidable. Even with all the advances in modeling, the dynamo still needs reformulation.
cantdrive85
1 / 5 (4) Mar 15, 2013
How "electric currents" (dynamo) are deduced by astrophysicists...
This is the next sentence from Q's quote;
Thanks to GONG, we know the internal velocity of the Sun. However, the other contributing effects, including the basic cyclonic nature of the updrafts in the convective zone, the meridional circulation across the upper and lower convective zone, the nature of the turbulent diffusion of the azimuth and poloidal magnetic fields, and the proper boundary conditions at the surface of the Sun, are not adequately known from observation, nor are they available from theoretical considerations. So the usual procedure is to IMAGINE a mathematical form that seems to describe each of the individual effects. Then we represent the strength of each effect with the appropriate parameter, i.e. coefficient, and proceed with the resulting dynamo equations to model our solar dynamo.


Here's where circuit theory would help greatly...
Q-Star
3.4 / 5 (5) Mar 16, 2013
It's not about merely mentioning some effect(magnetism, electricity, etc..), it's also about understanding the phenomenon. By calling the current a "magnetic fibril" shows a distinct ignorance of the observation.


It shows distinct ignorance on your part.

Obviously magnetism isn't ignored by astrophysicists, mainly because it is unavoidable. Even with all the advances in modeling, the dynamo still needs reformulation.


But ya have said hundreds of times that they "completely ignore", "refuse to address" and "never even mention". So now ya said ya didn't know what ya were talking about and just making things up?

I told ya that YOU would disagree with them. That's because ya don't and can't understand them.

Should I give weight to the writings of hundreds of people who have worked in the field for decades? Or should I rely on an internet troll who doesn't know anything and misquotes and can't understand even the people who he says make his point?

cantdrive85
1 / 5 (5) Mar 16, 2013
But ya have said hundreds of times that they "completely ignore", "refuse to address" and "never even mention". So now ya said ya didn't know what ya were talking about and just making things up?

Periodically they mention electric currents (Birkeland currents, current sheets, Io's electrical connection with Jupiter, etc.), but many times they use the same type astrophysical "code words", such as radiation belts, magnetic flux tubes, magnetic fibrils, extra-polar jets, solar wind, waves, and any number of other code words that are used to describe what are all electric currents. They see all of these events as disparate individual events and ignore the large scale circuitry that must be present to support all these individual currents.