Interaction of solar-related effects and stationary gravity wave above Aphrodite Terra according to VMC/Venus Express wind fields
Abstract
A set of UV (365 nm) images obtained by the Venus Monitoring Camera onboard Venus Express spacecraft was used to study the circulation of the atmosphere at upper boundary of clouds (70±2 km). 172000 displacement vectors (257 orbits) were obtained by digital wind tracking technique for observation period from 2006 to 2014. This data set allows studying both variation of the wind speed vs. latitude and longitude (correlation with surface topography) and dependence on local time.The zonal speed decrease was found above Aphrodite Terra. It has a solar-related character and strongly connected to the local noon. We studied the shape of the minimum wind speed structure (dependence of wind speed vs. longitude and latitude). It has an elongated shape in latitude. It was found that it repeats a contour of Aphrodite Terra at noon. The shape is conserved at least up to 30°S. In the same time, the wind speed increases by approximately 5 m/s to 30°S, and the area of minimum zonal speed shifts in direction of superrotation. The Sun influence manifests itself in the region of the stationary gravity waveexistence above Aphrodite Terra as the mean zonal flow deceleration in near equatorial latitudes (0-30°S). The zonal speed minimum is observed at noon above highest region of Ovda Regio (western part of Aphrodite Terra). Outside the Aphrodite Terra, the Sun influence does not manifest itself. The structure above highlands of Aphrodite Terra observed at noon may be a result of the stationary wave which generated by Aphrodite Terra and possible higher stability of the atmosphere, as a result of Solar heating, allow gravity waves to reach the upper clouds where they break and decelerate the mean zonal wind.J.-L. Bertaux, I.V. Khatuntsev and M.V. Patsaeva were supported by the Ministry of Education and Science of Russian Federation grant 14.W03.31.0017.
- Publication:
-
42nd COSPAR Scientific Assembly
- Pub Date:
- July 2018
- Bibcode:
- 2018cosp...42E2602P