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| Titel |
Mapping of SO₂ on Venus within the H2SO4 cloud using ground-based infrared imaging spectroscopy |
| VerfasserIn |
Thérèse Encrenaz, Thomas Greathouse, Matthew Richter, John Lacy, Bruno Bézard, Thierry Fouchet, Curtis DeWitt, Thomas Widemann |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250075285
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| Zusammenfassung |
| Sulfur dioxide and water vapor, two key parameters of Venus’ photochemistry, are known to exhibit significant spatial and temporal variations. In particular, ground-based thermal imaging spectroscopy at high resolution, achieved on Venus in January 2012, has shown evidence for strong SO2 variations on timescales shorter than a day (Encrenaz et al. AA 543, 153, 2012). We have continued our observing campaign using the TEXES high-resolution imaging spectrometer at the NASA Infrared Telescope Facility to map sulfur dioxide over the disk of Venus at two different wavelengths, 7 μm (already used in the previous study) and 19 μm. The 7 μm radiation probes the top of the H2SO4 cloud at about 65 km, while the 19 μm radiation probes at deeper levels within the cloud. Observations took place on October 4 and 5, 2012. The diameter of Venus was 15 arcsec, with an illumination factor of 72%. Data were recorded at 1343-1353 cm-1 during the two first hours of each run and at 529-531 cm-1 during the two last hours. The spectral resolving power and spatial resolution were, respectively, about 70000 and 1 arcsec at 7 μm, and 60000 and 1.5 arcsec at 19 μm. The Doppler velocity of Venus was + 12 km/s, corresponding to a Doppler shift of - 0.054 cm-1 at 1350 cm-1 and – 0.021 cm-1 at 530 cm-1. Both HDO and SO2 lines are identified in our 7 μm spectra and SO2 is also easily identified at 19 μm; the poor weather and the high water atmospheric content during our observing run limited the quality of the 7 μm observations. As observed in our previous run, the HDO map is relatively uniform over the disk of Venus. In contrast, the SO2 maps at 19 μm show intensity variations over the disk, as observed in January 2012 at 7 μm. In addition, the SO2 map at 19 μm shows significant changes within a timescale of an hour. The CO2 lines at 7 and 19 μm will be used to infer the thermal structure within the cloud and to study its latitudinal variations. |
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