atmosphère jupiter décryptee

Jupiter’s atmosphere is finally resolved

A collection of publications about Jupiter’s atmosphere flooded magazine columns Geophysical research letterAnd Science And Journal of Geophysical Research: Planets. Taken together, they allow us to understand Jupiter’s atmosphere like never before: its three-dimensional organization in convective cells and jet streams In depth, the true extent of the famous Great Red Spot and other surface vortices… At the origin of these simultaneous posts, several international teams of physicists interpreted the latest observational data from the Juno probe, which was put into orbit around the gas giant on July 5, 2016.

« It’s like opening a treasure chest “,” marvels NS Laurie Gleese, director of the Planetary Science Division at NASA. We understand it: Since it reached orbit of Jupiter in July 2016, the probe has provided more accurate data on the gas giant than anything physicists have had before. Analyzes of this data were published this week in the form of six articles, which have appeared in three major journals: Science (who are they Leaves), Geophysical research letter (who are they contributions also), and Journal of Geophysical Research: Planets (who are they Articles Moreover).

But what data can explain the nature of the pea puree formed by Jupiter? First, microwaves, those electromagnetic waves whose wavelength is between 1 mm and 1 meter. During 37 passes of Juno, 4,200 km from the surface of the gas giant, its on-board instruments have collected valuable information, in particular thanks to the microwave radiometer – a remote sensing instrument that measures and makes possible the energies emitted by various particles. To paint a vertical picture of the abundance of these organisms, despite the (very) heavy weather that prevails at the surface of the Jovian atmosphere.

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Jovian’s atmosphere is 3D designed

Second, 3D models of the behavior of Jupiter’s atmosphere were crucial to the analysis of the signals collected by Juno. This made it possible, for example, to determine the optimal atmospheric model to explain the distribution of ammonia – the NH4OH molecule, at the origin of urine odor and toxic in high concentrations – on Jupiter. ” It has been shown that the atmosphere consists of convective cells, such as terrestrial Ferrel cells. “,” details about Keren Doerr, researcher at the Weizmann Institute of Science and co-author of one of the publications.

The ammonia distribution anomalies observed in Jupiter’s atmosphere (in b, the red regions are richer in ammonia, and the blue regions are poorer) are consistent with the anomalies predicted by a convection model similar to that of Ferrell cells. (in c). In a, the vertical winds used in the model (ascending in red, descending in green). © Duer et al./Geophysical Research Letters

These Ferrel-like convective cells — regions of Earth’s atmosphere between 30 and 60 degrees latitude, where air circulates in a loop — appear blue in the article’s title image. Finally, under the convective cells are strong laminar currents called jet currents, certainly at the origin of Jupiter’s ranges.

Besides strong turbulence, Jupiter’s atmosphere is known for the wonderfully colored bands that tear it from east to west. Juno had previously determined that these were powerful jets, blowing at a speed of more than 500 km / h. But now, researchers have an idea of ​​the birth of these horizontal bands: they may come from deep platen jet streams, beneath Jovian convection cells.

Big red spot far from superficial

Another highly anticipated outcome concerns Jupiter’s Great Red Spot. First spotted by Cassini in 1665, this massive, massive hurricane is more than the diameter of the Earth.

« Juno previously surprised us by giving evidence that Jupiter’s atmosphere was deeper than expected. “,” explains to Scott Bolton, the main person in charge of the Juno mission. What recent discoveries clearly confirm: according to the analysis of density anomalies within the Jovian atmosphere, the Great Red Spot is shaking at a depth of at least 500 km! But that’s just the largest eddies – vortex storms – on Jupiter’s surface.

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Jupiter red stain
The Great Red Dot has been animated by Juno (along the two polychrome lines) to help illustrate its composition. © Parisi et al./Science

In general, the whirlpools turn into monstrous storms up to hundreds of kilometers thick, which penetrate to the depth at which water condenses into the icy and dark abyss of the gas giant. The state of matter changes, but the vortex continues!

« We call this critical depth the Jovicline, in reference to the Earth’s heat line [limite assez abrupte entre les eaux superficielles chaudes et les eaux profondes froides des océans] says Lee Fletcher, one of the lead scientists involved in the study. In other words, on Jupiter the state of the clouds changes (in addition to being filled with ammonia)! As if the ocean circulation and the atmospheric circulation were the same on Earth.

Jupiter Sofas Joe
Water condenses at 5-10 bar, but the vortex structure persists. © Bolton et al. / Science
Source : Science

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