Publications associated with Planetary Physics

Ammonia in Jupiter's Troposphere From High-Resolution 5 μm Spectroscopy

Geophysical Research Letters (2017)

RS Giles, LN Fletcher, PGJ Irwin, GS Orton, JA Sinclair

© 2017. American Geophysical Union. All Rights Reserved. Jupiter's tropospheric ammonia (NH 3 ) abundance is studied using spatially resolved 5 μm observations from the cryogenic high-resolution infrared spectrograph (CRIRES) at the European Southern Observatory's Very Large Telescope. The high-resolving power (R = 96,000) allows the line shapes of three NH 3 absorption features to be resolved. We find that within the 1-4 bar pressure range, the NH 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 3 enhancement at 4-6°N, consistent with a localized “ammonia plume“ on the southern edge of Jupiter's North Equatorial Belt.

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