Winds in the Middle Cloud Deck From the Near‐IR Imaging by the Venus Monitoring Camera Onboard Venus Express. Issue 11 (14th November 2017)

• Record Type: Journal Article
• Authors: Khatuntsev, I. V.; Patsaeva, M. V.; Titov, D. V.; Ignatiev, N. I.; Turin, A. V.; Fedorova, A. A.; Markiewicz, W. J.
• Is Part Of: Journal of geophysical research. Volume 122:Issue 11(2017)
• Page Start: 2312
• Page End: 2327
• Publication Date: 2017-11-14
• Subjects: Venus -- atmosphere -- dynamics -- data reduction techniques; Planets -- Periodicals; Geophysics -- Periodicals; 559.9
• DOI: 10.1002/2017JE005355
• Languages: English
• ISSNs: 2169-9097

Abstract

Abstract: For more than 8 years the Venus Monitoring Camera (VMC) onboard the Venus Express orbiter performed continuous imaging of the Venus cloud layer in UV, visible and near‐IR filters. We applied the correlation approach to sequences of the near‐IR images at 965 nm to track cloud features and determine the wind field in the middle and lower cloud (49–57 km). From the VMC images that spanned from December of 2006 through August of 2013 we derived zonal and meridional components of the wind field. In low‐to‐middle latitudes (5–65°S) the velocity of the retrograde zonal wind was found to be 68–70 m/s. The meridional wind velocity slowly decreases from peak value of +5.8 ± 1.2 m/s at 15°S to 0 at 65–70°S. The mean meridional speed has a positive sign at 5–65°S suggesting equatorward flow. This result, together with the earlier measurements of the poleward flow at the cloud tops, indicates the presence of a closed Hadley cell in the altitude range 55–65 km. Long‐term variations of zonal and meridional velocity components were found during 1, 200 Earth days of observation. At 20° ± 5°S the zonal wind speed increases from −67.18 ± 1.81 m/s to −77.30 ± 2.49 m/s. The meridional wind gradually increases from +1.30 ± 1.82 m/s to +8.53 ± 2.14 m/s. Following Bertaux et al. (2016) we attribute this long‐term trend to the influence from the surface topography on the dynamical process in the atmosphere via the upward propagation of gravity waves that became apparent in the VMC observations due to slow drift of the Venus Express orbit over Aphrodite Terra. Key Points: VMC near‐IR (965 nm) images of Venus dayside were used to derive atmospheric circulation in the middle cloud layer For the first time the closed Hadley cell that encompasses the upper cloud layer (55–67 km) was observed Zonal and meridional components of wind speed in the Venusian middle cloud demonstrate a connection with the underlying topography