Solar Related Waves in the Venusian Atmosphere from the Cloud Tops to 100 km

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  • 1 Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109
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Abstract

A diagnostic, quasi-linear model has been developed which uses observed solar-related temperatures and a specified zonal mean circulation and thermal structure to find the solar-related circulation above the clouds of Venus. Because there are no observations of the mean circulation above the clouds, it has been calculated using an independent model. Although the model-derived, solar-related circulation depends on the mean flow to a much greater degree than is the case for terrestrial tides, and although there is uncertainty in this mean flow, several important conclusions have been drawn concerning the solar-related circulation and thermal structure. Given that the solar forcing is likely to have a maximum in equatorial regions. there is an anomalously large response in the polar regions. It is primarily because of this unusual polar thermal structure that the model requires some process, such as dissipation, to act as an important sink for momentum. In the model, dissipation is specified as a Rayleigh friction whose coefficient is an unknown, free parameter. If such a formalism is correct, it is concluded that either the dissipation is extremely efficient by terrestrial standards and the solar-related circulation is small, or the dissipation is similar to that of the earth and the circulation is likely to be large enough to have an impact on the mean circulation.

Abstract

A diagnostic, quasi-linear model has been developed which uses observed solar-related temperatures and a specified zonal mean circulation and thermal structure to find the solar-related circulation above the clouds of Venus. Because there are no observations of the mean circulation above the clouds, it has been calculated using an independent model. Although the model-derived, solar-related circulation depends on the mean flow to a much greater degree than is the case for terrestrial tides, and although there is uncertainty in this mean flow, several important conclusions have been drawn concerning the solar-related circulation and thermal structure. Given that the solar forcing is likely to have a maximum in equatorial regions. there is an anomalously large response in the polar regions. It is primarily because of this unusual polar thermal structure that the model requires some process, such as dissipation, to act as an important sink for momentum. In the model, dissipation is specified as a Rayleigh friction whose coefficient is an unknown, free parameter. If such a formalism is correct, it is concluded that either the dissipation is extremely efficient by terrestrial standards and the solar-related circulation is small, or the dissipation is similar to that of the earth and the circulation is likely to be large enough to have an impact on the mean circulation.

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