Nasa’s Juno mission, the solar-powered robotic explorer of Jupiter, has completed its five-year prime mission to reveal the inner workings of the Solar System’s biggest planet. The most recent findings from these measurements have now been published in a series of papers, revealing the three-dimensional structure of Jupiter’s weather systems — including of its famous Great Red Spot, a centuries-old storm big enough to swallow the Earth whole. The Conversation reports: Jupiter’s Great Red Spot has had a hard time in recent years. […] But fans of the storm can take comfort from Juno’s latest findings. In 2017, Juno was able to observe the red spot in microwave light. Then, in 2019, as Juno flew at more than 200,000 kilometers per hour above the vortex, Nasa’s Deep Space Network was monitoring the spacecraft’s velocity from millions of kilometers away. Tiny changes as small as 0.01 millimeters per second were detected, caused by the gravitational force from the massive spot. By modeling the microwave and gravity data, my colleagues and I were able to determine that the famous storm is at least 300 km (186 miles) deep, maybe as deep as 500 km (310 miles). That’s deeper than the expected cloud-forming “weather layer” that reaches down to around 65 km (40 miles) below the surface, but higher than the jet streams that might extend down to 3,000 km (1,864 miles). The deeper the roots, the more likely the Red Spot is to persist in the years to come, despite the superficial battering it has been receiving from passing storms. To place the depth in perspective, the International Space Station orbits ~420 km (260 miles) above Earth’s surface. Yet despite these new findings, the spot could still be a “pancake-like” structure floating in the bottomless atmosphere, with the spot’s 12,000 km (7,456 mile) width being 40 times larger than its depth.

In the cloud-forming weather layer, Juno’s microwave antennae saw the expected structure of belts and zones. The cool zones appeared dark, indicating the presence of ammonia gas, which absorbs microwave light. Conversely, the belts were bright in microwave light, consistent with a lack of ammonia. These bright and dark bands in the weather layer were perfectly aligned with the winds higher up, measured at the top of the clouds. But what happens when we probe deeper? The temperature of Jupiter’s atmosphere is just right for the formation of a water cloud around 65 km (40 miles) down below the cloud tops. When Juno peered through this layer, it found something unexpected. The belts became microwave-dark, and the zones became microwave-bright. This is the complete reverse of what we saw in the shallower cloudy regions, and we are calling this transition layer the “jovicline” — some 45-80 km (28-50 miles) below the visible clouds. […] The jovicline may separate the shallow cloud-forming weather layer from the deep abyss below. This unexpected result implies something is moving all that ammonia around.

One possibility is that each jet stream is associated with a “circulation cell,” a climate phenomenon that moves gases around via currents of rising and falling air. The rising could cause ammonia enrichment, and the sinking ammonia depletion. If true, there would be about eight of these circulation cells in each hemisphere. […] Other meteorological phenomena might be responsible for moving the ammonia around within this deep atmosphere. For example, vigorous storms in Jupiter’s belts might create mushy ammonia-water hailstones (known as “mushballs”), which deplete ammonia within the shallow belts before falling deep, eventually evaporating to enrich the belts at great depths.

Read more of this story at Slashdot.

Source: Slashdot – Juno Reveals Deep 3D Structure of Jupiter’s Massive Storms