تقرير
Latitudinal Variations in Methane Abundance, Aerosol Opacity and Aerosol Scattering Efficiency in Neptune's Atmosphere Determined from VLT/MUSE
| العنوان: | Latitudinal Variations in Methane Abundance, Aerosol Opacity and Aerosol Scattering Efficiency in Neptune's Atmosphere Determined from VLT/MUSE |
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| المؤلفون: | P. G. J. Irwin, J. Dobinson, A. James, M. H. Wong, L. N. Fletcher, M. T. Roman, N. A. Teanby, D. Toledo, G. S. Orton, S. Pérez-Hoyos, A. Sánchez-Lavega, A. Simon, R. Morales-Juberias, I. de Pater |
| المصدر: | Journal of Geophysical Research: Atmospheres. 128(11) |
| بيانات النشر: | United States: NASA Center for Aerospace Information (CASI), 2023. |
| سنة النشر: | 2023 |
| مصطلحات موضوعية: | Geophysics |
| الوصف: | Spectral observations of Neptune made in 2019 with the Multi Unit Spectroscopic Explorer (MUSE) instrument at the Very Large Telescope (VLT) in Chile have been analyzed to determine the spatial variation of aerosol scattering properties and methane abundance in Neptune's atmosphere. The darkening of the South Polar Wave at ∼60°S, and dark spots such as the Voyager 2 Great Dark Spot is concluded to be due to a spectrally dependent darkening (λ < 650 nm) of particles in a deep aerosol layer at ∼5 bar and presumed to be composed of a mixture of photochemically generated haze and H2S ice. We also note a regular latitudinal variation of reflectivity at wavelengths of very low methane absorption longer than ∼650 nm, with bright zones latitudinally separated by ∼25°. This feature, which has similar spectral characteristics to a discrete deep bright spot DBS-2019 found in our data, is found to be consistent with a brightening of the particles in the same ∼5-bar aerosol layer at λ > 650 nm. We find the properties of an overlying methane/haze aerosol layer at ∼2 bar are, to first-order, invariant with latitude, while variations in the opacity of an upper tropospheric haze layer reproduce the observed reflectivity at methane-absorbing wavelengths, with higher abundances found at the equator and also in a narrow “zone” at 80°S. Finally, we find the mean abundance of methane below its condensation level to be 6%–7% at the equator reducing to ∼3% south of ∼25°S, although the absolute abundances are model dependent. |
| نوع الوثيقة: | Report |
| اللغة: | English |
| تدمد: | 2169-8996 2169-897X |
| DOI: | 10.1029/2023JE007980 |
| URL الوصول: | https://ntrs.nasa.gov/citations/20230016814 |
| ملاحظات: | 315404.07.02.22.01.14 80NM0018D0004 UK Irwin: ST/S000461/1 UK Teanby: ST/R000980/1 EUH 2020 723890 PID2019-109467GB-I00 Elkartek21/87 KK-2021/00061 Grupos Gobierno Vasco IT-1742-22 |
| رقم الأكسشن: | edsnas.20230016814 |
| قاعدة البيانات: | NASA Technical Reports |
Full Text Finder | تدمد: | 21698996 2169897X |
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| DOI: | 10.1029/2023JE007980 |