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Radiative Transfer Modeling of Jupiter’s Hot Spots and NH₃ Plumes with HST UVIS and Keck NIRSPEC

Presentation #100.03 in the session “Giant Planets 1: Jupiter”.

Published onOct 26, 2020
Radiative Transfer Modeling of Jupiter’s Hot Spots and NH₃ Plumes with HST UVIS and Keck NIRSPEC

Hot spots are downwelling regions of the Jovian atmosphere that appear bright in the thermal infrared and dark at visible wavelengths, owing to a combination of low ammonia (NH3) abundances and thin clouds. They open a window into Jupiter’s deeper atmospheric layers, which are normally obscured by overlying clouds, providing sensitivity to layers as deep as ~6 bar. Conversely, NH3 plumes are upwelling regions with thick overlying clouds and high NH3 abundances, which appear bright at visible wavelengths and dark in the thermal infrared. NH3 is a tracer of atmospheric dynamics, so studying these NH3 extremes is important for understanding the vertical transport of volatiles in Jupiter’s atmosphere. We present radiative transfer (RT) models of hot spots and NH3 plumes found in Jupiter’s North Equatorial Belt (NEB). Our models use observations at visible (0.3-0.9 μm) and thermal infrared (4.5-5.5 μm) wavelengths from the HST WFC3/UVIS and Keck NIRSPEC instruments, respectively. These observations are part of a suite of Juno support observations, which include simultaneous observations with HST, Keck, Gemini, and the Very Large Array. HST observations are sensitive to atmospheric conditions between the tropopause at ~0.1 bar down to the uppermost opaque cloud tops, which range from ~0.7–4 bar depending on cloud opacities. Our NIRSPEC observations are sensitive to cloud opacities and volatile abundances between ~2–6 bar. We combine these two datasets to simultaneously model the structure and composition of Jupiter’s hot spots and NH3 plumes from ~0.1–6 bar. We use our in-house RT modeling package, SUNBEAR, to derive the extent and thickness of tropospheric hazes, the location and structure of Jupiter’s clouds, and the abundances of volatiles such as NH3.

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