The Depth of vortices in Jupiter’s atmosphere

For over 100 years, Jupiter has been observed and its atmosphere characterized by a well

organized system of zones and belts disrupted by storms and vortices such as the Great

Red Spot (GRS). Jupiter’s weather layer, where storms, vortices, and convective clouds are observed, was expected to be constrained to depths above which sunlight penetrates and/or where water condenses.  In 1995, NASA’s Galileo probe challenged this expectation by finding that water was not well mixed even well below its expected condensation level (1). Early results from Juno extended the puzzle by discovering that both ammonia and water vary across most of the planet at much greater depths than their expected saturation levels (2,3,4), and that the gravitational signatures of the atmospheric zonal flows are present at depths approaching 3000 km (5,6) .The depth that atmospheric vortices penetrate provide a means to investigate how the details of volatile condensation shape Jupiter’s weather, and assess the relative importance of moist convection, baroclinic instability and deep convection in models of vortex creation and stability.

 

The Microwave Radiometer (MWR) instrument (2,7) on the Juno spacecraft is a set of radiometers designed to measure Jupiter’s emitted flux (or equivalently brightness temperature) at a range of depths from top of the atmosphere to over 600 km beneath the visible cloud tops. The instrument observes at six individual frequencies between 0.6 to 22 GHz (wavelengths 50 cm – 1.3 cm), each sampling a different depth determined by how atmospheric transparency varies with frequency. We report on the vertical structure of vortices observed April 2019, comparing the vertical structures of Jupiter’s cyclones and anticyclones, including the Great Red Spot (GRS) which was observed by Juno in July 2017. We show vortex roots can extend deeper than the region where water is expected to condense and are characterized with density inversion layers.

 

Juno’s extended mission offers opportunities to explore the depth of Jovian meteorological phenomena including the vortices encircling the north pole.  A sampling of recent microwave maps of Jupiter’s north polar region will be also be shown. 

 

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