Chris Watkins and James Y-K. Cho
Extrasolar planets are expected to possess strongly stratified atmospheres, which support gravity waves. The importance of these waves on Solar System planets is well known. In this work, we study the propagation of gravity waves in hot extrasolar planet atmospheres, focusing on the horizontal component of the propagation. We review the derivation of the equation that governs the dynamics of small-amplitude gravity waves and apply it to the specific case of the extrasolar planet HD209458b, a representative "hot-Jupiter" planet. We show that the waves can significantly accelerate or decelerate the background mean flow, by transporting momentum between atmospheric regions. They can also provide significant heating to the regions of the atmosphere far from the source location. On close-in extrasolar planets, which are expected to be tidally locked, horizontal propagation provides a mechanism for transporting heat and momentum between the day and night sides, helping to homogenize the atmosphere. We also discuss possible steps towards parametrizing the effects of horizontal propagation, enabling more accurate general circulation model simulations of extrasolar planets.
Author entry (protected)