Stationary wave dynamics in Venus's upper clouds

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Context . Stationary waves play a crucial role in vertically transporting momentum and energy in Venus’s atmosphere. Their global contributions (approximately −0.1 m s −1 day −1 at the upper cloud) are smaller than those of planetary-scale waves and meridional circulation (approximately ±1.0 m s −1 day −1 ), but stationary waves exert strong regional control, shaping the longitudinal structure of the super-rotating flow above highlands. Observations have linked wave signatures near the cloud top (~70 km) to underlying highland regions. However, their vertical propagation characteristics and contributions to the morphology of super-rotation remain poorly understood. Aims . This study aims to characterize the structure, variability, and propagation of stationary waves in Venus’s atmosphere and to evaluate their role in modulating the longitudinal structure of cloud-top super-rotation. Methods . We analyzed eight years of thermal emission data from Akatsuki/LIR to isolate stationary wave components. Simulations were performed using the high-resolution Venus planetary climate model, which incorporates a realistic topography and a hybrid vertical coordinate system. Results . Stationary wave signatures in the brightness temperature and horizontal winds are consistently observed and simulated above highland regions, with a notable local time dependence and long-term variability. The vertical transport of angular momentum and heat dominates the wave-induced momentum and energy budget, leading to zonal wind deceleration and adiabatic heating in the upper cloud layer. Despite filtering by two weak static stability layers in the deep atmosphere, stationary waves can propagate upward and impact cloud-top dynamics. Conclusions . Stationary waves exert a measurable influence on Venus’s upper-cloud super-rotation by vertically redistributing momentum and heat in longitude. Their effects are modulated by both vertical static stability and diurnal variations. These results highlight the crucial role of stationary waves in maintaining the observed longitudinal structure of the super-rotating atmosphere.

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