J. Peralta, A. Sánchez-Lavega, M. A. López-Valverde, D. Luz, P. Machado

Abstract
The superrotation of the atmospheres of slowly rotating bodies is a long-standing problem yet unsolved in atmospheric dynamics. On Venus, the most extreme case known of superrotation, this is accompanied and influenced by a recurrent planetary-scale cloud structure, known as the Y feature. So far, no model has simultaneously reproduced its shape, temporal evolution, related wind field, nor the relation between its dynamics and the unknown UV-absorbing aerosol that produces its dark morphology. In this paper we present an analytical model for a Kelvin-like wave that offers an explanation of these peculiarities. Under Venus cyclostrophic conditions, this wave is equatorially and vertically trapped where zonal winds peak and extends 7 km in altitude, and its vertical wind perturbations are shown to produce upwelling of the UV absorber. The Y-feature morphology and its 30 day evolution are reproduced as distortions of the wave structure by the Venus winds.

Geophysical Research Letters
Volume 42, Number 3, Page 705
2015 March

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