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Color and Structure of Jupiter’s Uppermost Cloud Deck During the Juno Era

Presentation #112.03D in the session “Gas Giant Atmospheres”.

Published onOct 03, 2021
Color and Structure of Jupiter’s Uppermost Cloud Deck During the Juno Era

Both the identity of the coloring agents in Jupiter’s atmosphere and the exact structure of Jupiter’s uppermost cloud deck are yet to be conclusively understood. While the arrival of the Juno spacecraft at Jupiter in July 2016 heralded a new era of exploration of the Jovian system, Juno’s visible camera lacks the spectral resolution necessary to comprehensively probe the altitude, structure, and color of the uppermost cloud deck. As part of an international ground-based observing campaign in support of the Juno mission, we used the New Mexico State University Acousto-optic Imaging Camera (NAIC) at the Astrophysical Research Consortium 3.5-m telescope at Apache Point Observatory in Sunspot, NM. NAIC captured optical hyperspectral image cubes of Jupiter from 470 to 950 nm whenever Juno completed a close perijove pass of the planet and viewing geometry allowed. In total, we successfully obtained data during 13 Juno perijove passes from 2016-2020. These data were used to test a parameterization of Jupiter’s clouds called the Crème Brûlée model, which presumes that a relatively thin chromophore haze layer sits directly above a main tropospheric cloud deck. This theorized chromophore layer, which contains coloring agents formed from upwelling, photolyzed ammonia reacting with acetylene, is presumed to be the singular coloring agent in Jupiter’s troposphere. Jupiter’s varied reddish hues result from this universal chromophore being present in different amounts in different locations. In this dissertation talk, I present the results of using radiative transfer models and NAIC spectra of different locations in Jupiter's atmosphere to test the validity of the Crème Brûlée parameterization of the uppermost cloud deck. These tests were completed for observations in support of two of Juno’s perijove passes, PJ5 and PJ19, and for several different major cloud features during both active weather events and quiescent periods. We found that the Crème Brûlée model of Jupiter’s atmosphere is generally a valid parameterization for these varied cloud features, but we also found that the “classical” Crème Brûlée model isn't always practical for unique weather events, such as outbreak storms or Equatorial Zone disturbances. However, with some modifications, such as a “younger,” more reflective chromophore or a more vertically extended stratospheric haze layer, this parameterization still provides satisfactory spectral fits to our spectra.

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