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T. Satoh (Kumamoto U.), M. Ueno, N. Iwagami (U. of Tokyo), M. Taguchi (NIPR), S. Watanabe (Hokkaido U.), Y. Takahashi (Tohoku U.), M. Suzuki (EORC/JAXA), T. Imamura, M. Nakamura (ISAS/JAXA)
The super-rotation of Venus atmosphere is phenomenologically well-known although its generation and maintenance mechanism is not yet well understood. None of various mechanisms so far proposed is widely accepted primarily because we know so little about the atmospheric circulation below the thick clouds. Five cameras onboard Venus Climate Orbiter (VCO) are dedicated to meteorological study and will observe the key processes driving the super-rotation. IR1 (1.01 \mum) and IR2 (1.735/2.02/2.26/2.32 \mum) will observe the clouds and minor constituents in the deep atmosphere through the near-IR windows. IR1 quantifies the wind-field in the cloud region (45-60 km) over the day-side hemisphere. On the night-side, IR1 is sensitive to conditions near the surface while IR2 is sensitive to slightly higher altitude (30 km). Both camera will detect atmospheric motions throughout the clouds. We also expect IR1 to find out (possible) active volcanoes, yielding information on the internal structure and the thermal history of Venus as well as the atmospheric evolution. LIR (8-12 \mum) will measure the thermal radiation emitted from the cloud-top and will characterize the horizontal wind vector field and temperature variations with an accuracy of 3 K. LIR can continuously provide a hemispheric view independent of the phase, an advantage of this instrument. UVI (280/365 nm) is designed to measure the ultraviolet radiation, scattered at the cloud tops of 70-km altitude. The wavelength 365 nm includes an absorption of unidentified constituent which is believed to be important to the energy balance and the dynamics of the Venus atmosphere. LAC (551/558/777 nm) is a high-speed imaging sensor and measures lightning flashes and airglow emissions on the night-side disk of Venus when VCO is located within the umbra of Venus. VCO has been in Phase B study since 2004 and is expected to be launched around 2009-2010.
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Bulletin of the American Astronomical Society, 37 #3
© 2004. The American Astronomical Soceity.