A Study of Cloud Morphologies, Horizontal Wind Shear, and the Equatorial Jet on the Nightside Middle Atmosphere of Venus
Abstract
The nightside middle cloud layer of Venus is home to many irregular cloud formations including gravity waves, discontinuities, and eddies. The eddies are likely horizontal wind shear formations and have been noticed in previous studies. This research aims to examine the formation, frequency, and distribution of the eddies on the nightside of Venus. We analyzed images taken at a wavelength of 2.26 µm from the IR2 camera aboard the Venus Climate Orbiter for eddies, hooks, or eyes. Wind velocity on the night side was extracted from published data sets and interpolated to form a continuous plot that reveals the equatorial jet, a periodic long-term event. The wave formations are often co-located with areas of high wind shear. The horizontal divergence was calculated and was low in the areas of high wind shear, indicating very little vertical motions. We find that the meridional wind component is an order of magnitude lower than the zonal winds. This tells us the wind shear is zonal. The zonal winds are negligibly affected by the Coriolis force. These waves were observed to remain between a latitude band of 27 degrees N - 32 degrees S. The distribution of the longitudes of the eddies was positively skewed with more eddies at low longitudes. This could indicate a topographical influence on the formation of the eddies or the equatorial jet. There were no waves found at the equator, lending to the hypothesis that the equatorial jet produces horizontal wind shear on either side of the equator. The waves occurred in the regions of high wind shear, on the edges of the jet. The northern flank is favoured in the distribution of the eddies. The winds were observed to linearly decrease in velocity with respect to local time, at different rates depending on the latitude. Northern latitudes were observed to decrease the slowest, and equatorial winds decrease the fastest. This in addition to the thermal tide could lend a hand in the creation of the equatorial jet. This research is important to the understanding of momentum transport in the atmosphere of Venus. The horizontal momentum transport by eddies caused by the equatorial jet could have an effect on larger dynamical features in the Venusian atmosphere.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2021
- Bibcode:
- 2021AGUFM.P53A..06C