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| Titel |
Models for Temperature and Composition in Uranus from Spitzer, Herschel and Ground-Based Infrared through Millimeter Observations |
| VerfasserIn |
Glenn Orton, Leigh Fletcher, Helmut Feuchtgruber, Emmanuel Lellouch, Raphaël Moreno, Paul Hartogh, Christopher Jarchow, Bruce Swinyard, Julianne Moses, Martin Burgdorf, Heidi Hammel, Michael Line, Amy Mainzer, Mark Hofstadter, Goran Sandell, Charles Dowell |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250098386
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| Publikation (Nr.) |
 EGU/EGU2014-14057.pdf |
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| Zusammenfassung |
| Photometric and spectroscopic observations of Uranus were combined to create
self-consistent models of its global-mean temperature profile, bulk composition,
and vertical distribution of gases. These were derived from a suite of spacecraft
and ground-based observations that includes the Spitzer IRS, and the Herschel
HIFI, PACS and SPIRE instruments, together with ground-based observations from
UKIRT and CSO. Observations of the collision-induced absorption of H2 have
constrained the temperature structure in the troposphere; this was possible up to
atmospheric pressures of ~2 bars. Temperatures in the stratosphere were constrained by
H2 quadrupole line emission. We coupled the vertical distribution of CH4 in the
stratosphere of Uranus with models for the vertical mixing in a way that is consistent with
the mixing ratios of hydrocarbons whose abundances are influenced primarily by
mixing rather than chemistry. Spitzer and Herschel data constrain the abundances of
CH3, CH4, C2H2, C2H6, C3H4, C4H2, H2O and CO2. The Spitzer IRS data, in
concert with photochemical models, show that the atmosphere the homopause is
much higher pressures than for the other outer planets, with the predominant trace
constituents for pressures lower than 10 μbar being H2O and CO2. At millimeter
wavelengths, there is evidence that an additional opacity source is required besides
the H2 collision-induced absorption and the NH3 absorption needed to match the
microwave spectrum; this can reasonably (but not uniquely) be attributed to H2S.
These models will be made more mature by consideration of spatial variability
from Voyager IRIS and more recent spatially resolved imaging and mapping from
ground-based observatories. The model is of ‘programmatic’ interest because it
serves as a calibration source for Herschel instruments, and it provides a starting
point for planning future spacecraft investigations of the atmosphere of Uranus. |
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