Ammonia in Jupiter's troposphere from high-resolution 5-\textmu m spectroscopy [EPA]

Jupiter’s tropospheric ammonia (NH\textsubscript{3}) abundance is studied using spatially-resolved 5-\textmu m observations from CRIRES, a high resolution spectrometer at the European Southern Observatory’s Very Large Telescope. The high resolving power (R=96,000) allows the line shapes of three NH\textsubscript{3} absorption features to be resolved. We find that within the 1–4 bar pressure range, the NH\textsubscript{3} abundance decreases with altitude. The instrument slit was aligned north-south along Jupiter’s central meridian, allowing us to search for latitudinal variability. There is considerable uncertainty in the large-scale latitudinal variability, as the increase in cloud opacity in zones compared to belts can mask absorption features. However, we do find evidence for a strong NH\textsubscript{3} enhancement at 4–6$^{\circ}$N, consistent with a localised `ammonia plume’ on the southern edge of Jupiter’s North Equatorial Belt.

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R. Giles, L. Fletcher, P. Irwin, et. al.
Wed, 11 Oct 17

Comments: Manuscript accepted for publication in GRL