Jupiter: Great Red Spot Shallow and Deep Ends

What is it about?

Vertical fluid columns circulating around Jupiter's Great Red Spot take about six days to complete a circuit. We tracked these columns and found that they spin twice as fast when they are on the poleward side of the Great Red Spot as when they are on the equatorward side. Such an increase in spin occurs when a column horizontally contracts, like a skater pulling in her arms. This in turn implies the column has vertically elongated, and thus has entered a deeper part of the atmosphere.

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Why is it important?

The fact that the thickness of the Great Red Spot varies by a factor of two from north to south implies that it is a shallow object. (Consider that it is common to grab for a thin sheet of paper and get two, but it is not common to grab for a thick ream of paper and get two.) This supports the theory that the Great Red Spot is an anticyclonic lens, making it dynamically similar to lens observed in Earth's oceans, like Mediterranean Salt lens ("meddies"), which float below the surface of the Atlantic Ocean and last for up to 5 years. The shallow-to-deep transition also implies that the Great Red Spot is overriding jet streams that run much deeper than the storm itself. This study provided the first empirical evidence that Jupiter has deep jet streams.

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