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F. Schmuelling (NRC at NASA/GSFC), J. Goldstein (CCSSE), T. Kostiuk (GSFC), T. Hewagama (UMD/GSFC), D. Zipoy (UMD)
We will present high accuracy measurements of line-of-sight wind velocities in the upper Venus atmosphere and models of the implied global circulation. The measurements were performed using the NASA/GSFC Infrared Heterodyne Spectrometer at the NASA IRTF. Thermospheric altitudes between 100 and 120 km were probed using ^{12}C^{16}O_2 solar-pumped, non-thermal emission. The observed signal-to-noise allowed determination of line center frequencies to a precision of~0.1\,MHz (1\,m/s at 10\,\mum). Absolute frequency calibration was possible to better than 0.1\,MHz due to the extremely high frequency stability of the Lamb-dip stabilized heterodyne system. The quality of the data together with the instrument stability allowed measurement of line-of-sight wind velocities across the illuminated crescent to 1\,m/s. Data were acquired just before and after inferior conjunction in 1990 and 1991. In combination, these two data sets allowed modeling of the global wind field. Modeled horizontal wind velocities will be presented for a sub-solar to anti-solar flow and a zonal retrograde super-rotation.