http://www.abc.net.au/science/articles/2013/05/16/3759940.htm#.UZtXZ7Uwd8G

_Neptune may have the fastest winds in the solar system, but they just skim across the top of the planet’s atmosphere, according to a new study.

The research, reported in the journal Nature, found the ice giants Neptune and Uranus both have a thin weather layer no more than 1000 kilometres deep.

The results indicate the dynamical atmosphere of Uranus and Neptune makes up only the outermost 0.15 per cent and 0.2 per cent of mass, respectively.

It implies that the dynamics controlling these winds probably come from shallow processes, rather than deep atmospheric circulation.

The source of energy powering these winds also remains a mystery.

It’s still unclear whether they’re driven by heating from the Sun, or by heat upwelling from deep inside the planet.

“In all atmospheres absorption of sunlight and the loss of heat to space, changes the density of the fluid (atmosphere) and those density and temperature differences cause the fluid (atmosphere) to move around,” says Showman.

But he points out when you’re 30 times further away from the Sun than Earth is, internal heat could have a much stronger influence.

“It would appear rotation of the planet and the stirring of the planet by small convective turbulence is the dominant factor in controlling the wind pattern,” says Showman.

“The way that the sunlight changes throughout the year (seasons) is a secondary factor.”_

Does this imply there is a substantial surface below the winds?

How much about the interior can be estimated from this?

Riff-in-Thyme said:

How much about the interior can be estimated from this?

Firstly it would be about mass.

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wookiemeister said:

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Riff-in-Thyme said:

Does this imply there is a substantial surface below the winds?

As the article says: “It implies that the dynamics controlling these winds probably come from shallow processes, rather than deep atmospheric circulation.”
So this information doesn’t tell us much about what it’s like deep inside the ice giants. Just that whatever is happening deeper down has little impact on the winds in the upper atmosphere.

Current models suggest that beneath the atmosphere of an ice giant is a hot, highly dense fluid mostly consisting of volatile compounds like water, ammonia & methane. Planetary astronomers traditionally refer to such substances as ices, hence the name “ice giant”, but the ices in an ice giant are certainly not cold or particularly solid.

See https://en.wikipedia.org/wiki/Neptune#Internal_structure

PM 2Ring said:

but the ices in an ice giant are certainly not cold or particularly solid.

See https://en.wikipedia.org/wiki/Neptune#Internal_structure

but massive.

Riff-in-Thyme said:

How much about the interior can be estimated from this?

It’s actually the other way around, these depths of winds are calculated from a re-analysis of the distribution of mass in the interiors of Uranus and Neptune. The analysis uses the orbits of passing spacecraft to determine a particular property of the mass distribution in the interior, it’s deviation from spherical, and from that shows that surface winds can’t be deep because if they were then the distribution of mass would be different.

All this begs the question of the magnetic fields of Neptune and Uranus. These are both wildly off-centre and both driven by dynamo action. That means that there is a substantial circulation of liquid in a electrically-conducting spherical shell deep within the structure of Uranus and Neptune. It has been suggested that ocean currents in a salt-water ocean deep within the planets is responsible for these magnetic fields. The present study failed to find any evidence that this circulation is linked in any way to the surface winds.