Hemispheric distributions of HCl above and below the Venus' clouds by ground-based 1.7 μm spectroscopy

N. Iwagami, S. Ohtsuki, K. Tokuda, N. Ohira, Y. Kasaba, T. Imamura, H. Sagawa, G. L. Hashimoto, S. Takeuchi, M. Ueno, S. Okumura

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18 Citations (Scopus)

Abstract

The abundance of hydrogen chloride (HCl) in the Venus atmosphere was measured by ground-based IR spectroscopy. The dayside measurements were performed in May 2007 with a resolution of 40,000, and the nightside measurements in October 1999 with a resolution of 1000. The hemispheric distributions of the HCl mixing ratio measured above the Venus' clouds show no significant structure with a disc-averaged value of 0.74±0.06 ppm which is in the similar range as the previous report of 0.6±0.2 ppm. The representative height for the dayside measurements is estimated to be 60-66 km. Recent results by Venus Express/SPICAV/SOIR show much smaller values of 0.1-0.2 ppm at 64-94 km; however the direct comparison is difficult due to the different spatial conditions. The hemispheric distributions of the 35Cl/37Cl isotope ratio are also found to show no significant structure with a disc-averaged value of 3.1±0.4 which coincides with the terrestrial value of 3.1. The HCl mixing ratios below the clouds are also found to show no significant structure with a disc-averaged value of 0.40±0.05 ppm, which is similar to the previous reports of 0.4-0.5 ppm. The larger HCl mixing ratio above the clouds than below suggests the production of HCl in the cloud region or above. Also, a uniform hemispherical distribution of H2O is found below the clouds with a disc-averaged mixing ratio of 25±5 ppm; this is in the same range as the previous measurements. Those uniform distributions of HCl and H2O support the fact that their chemical lifetimes are much longer than that of mixing as has been discussed so far.

Original languageEnglish
Pages (from-to)1424-1434
Number of pages11
JournalPlanetary and Space Science
Volume56
Issue number10
DOIs
Publication statusPublished - Aug 1 2008
Externally publishedYes

Keywords

  • Atmosphere
  • HCl
  • HO
  • Infrared
  • Venus

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Iwagami, N., Ohtsuki, S., Tokuda, K., Ohira, N., Kasaba, Y., Imamura, T., Sagawa, H., Hashimoto, G. L., Takeuchi, S., Ueno, M., & Okumura, S. (2008). Hemispheric distributions of HCl above and below the Venus' clouds by ground-based 1.7 μm spectroscopy. Planetary and Space Science, 56(10), 1424-1434. https://doi.org/10.1016/j.pss.2008.05.009