Kelvin Wave and Its Impact on the Venus Atmosphere Tested by Observing System Simulation Experiment

Abstract

At the cloud top of the Venus atmosphere, equatorial Kelvin waves have been observed and are considered to play an important role in the super-rotation. We were able to reproduce the wave in a general circulation model (GCM) by conducting an observing system simulation experiment (OSSE) with the help of a data assimilation system. The synthetic horizontal winds of the Kelvin wave produced by the linear wave propagating model are assimilated at the cloud top (~70 km) in realistic conditions, assuming they are obtained from cloud tracking of ultra-violet images (UVI) taken by the Venus orbiters. It is demonstrated using Eliassen–Palm (EP) fluxes that the reproduced Kelvin wave transports angular momentum and plays an important role in the magnitude and structure of the super-rotation, causing the acceleration and deceleration of zonal wind of ~0.1 m/s day−1. The conditions required in order to reproduce the Kelvin wave have also been investigated. It is desirable to have 24 hourly dayside satellite observations in an equatorial orbit, such as the Akatsuki Venus climate orbiter. The results of this type of data assimilation study will be useful in the planning of future observation missions to the atmospheres of planets.

The first assimilation of Akatsuki single-layer winds and its validation with Venusian atmospheric waves excited by solar heating

“…In this study, we mainly focused on the thermal tide in the analysis for just one period. In the previous data assimilation test studies, it has been reported that the cold collar 49 and planetary-scale Kelvin waves 50 , 51 could be reproduced with sufficiently frequent observations. We are now planning to produce analyses with a number of observation periods, with which such kind of short period disturbances can be reproduced and investigated widely in the Venus research community.…”