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Science 31 May 1991:
Vol. 252. no. 5010, pp. 1293 - 1296
DOI: 10.1126/science.252.5010.1293
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Articles

Spectroscopic Observations of Bright and Dark Emission Features on the Night Side of Venus

J. F. BELL III 1, D. CRISP 2, P. G. LUCEY 1, T. A. OZOROSKI 1, W. M. SINTON 2, S. C. WILLIS 3, and B. A. CAMPBELL 1

1 Planetary Geosciences Division, University of Hawaii, Honolulu,HI 96822 and Visiting Astronomers at the Infrared Telescope Facility, operated by the University of Hawaii under contract to the National Aeronautics and Space Administration
2 Jet Propulsion Laboratory and California Institute of Technology, Mail Stop 169-237, 4800 Oak Grove Drive, Pasadena, CA 91109
3 Institute for Astronomy, University of Hawaii, Honolulu, HI 96822

Near-infrared spectra of a bright and a dark thermal emission feature on the night side of Venus have been obtained from 2.2 to 2.5 micrometers (µm) at a spectral resolution of 1200 to 1500. Both bright and dark features show numerous weak absorption bands produced by CO2, CO, water vapor, and other gases. The bright feature (hot spot) emits more radiation than the dark feature (cold spot) throughout this spectral region, but the largest contrasts occur between 2.21 and 2.32 µm, where H2SO4 clouds and a weak CO2 band provide the only known sources of extinction. The contrast decreases by 55 to 65 percent at wavelengths longer than 2.34 µm, where CO, clouds, and water vapor also absorb and scatter upwelling radiation. This contrast reduction may provide direct spectroscopic evidence for horizontal variations in the water vapor concentrations in the Venus atmosphere at levels below the cloud tops.

Submitted on January 17, 1991
Accepted on April 3, 1991


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Ground-Based Near-Infrared Imaging Observations of Venus During the Galileo Encounter.
D. Crisp, D. CRISP, S. MCMULDROCH, S. K. STEPHENS, W. M. SINTON, B. RAGENT, K. -W. HODAPP, R. G. PROBST, L. R. DOYLE, D. A. ALLEN, et al. (1991)
Science 253, 1538-1541
   Abstract »    PDF »
The dark side of Venus: near-infrared images and spectra from the Anglo-Australian observatory.
D Crisp, D. Allen, D. Grinspoon, and J. Pollack (1991)
Science 253, 1263-1266
   Abstract »    PDF »


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