Wind Field in Venus' Lower Mesosphere
Abstract
Venus mesosphere (70-110 km) is characterized by two different circulation regimes : (1) the upper part of super-rotation which is expected to decrease with height in the lower mesosphere (70-85 km) and where zonal winds show strong variations ; (2) a stable axisymmetrical sub-solar to anti-solar (SSAS) circulation resulting from solar EUV heating above 120 km. Information on the global wind field is provided by the horizontal distribution of CO and the O2 airglows but its detailed structure remains poorly understood. First attempts to measure Venus winds from Doppler shift spectroscopy date back to the mid-1970s (Young et al. 1979 Traub and Carleton 1979). Although unconclusive at that time the technique deserves further investigation as providing unique information on the decrease of the super-rotation above the cloud tops. In 2001 and 2002 we observed the 5nu3 band of CO2 with a resolving power of 120000 in 3 arcsec-wide fields on the Venus disk and an accuracy of 10 to 20 ms-1. Seven points were observed on Venus' illuminated side using the disk center as a zero-velocity reference. Our preliminary results show that the circulation at 1-2 scale heights above cloud top is still dominated by zonal retrograde circulation.
- Publication:
-
IAU Special Session
- Pub Date:
- 2003
- Bibcode:
- 2003IAUSS...1E..11W