Simulation of deep-seated zonal jets and shallow vortices in gas giant atmospheres

摘要

Jupiter's banded cloud layer hosts spots of various sizes. The bands are defined by eastward and westward jet streams and the spots correspond to vortices, predominantly anticyclones, which rotate in the opposite direction of Earth's cyclonic storms(1-3). Despite 350 years of observation(4), the origin and dynamics of jets and vortices in the atmospheres of giant planets remain debated. Simulations of the shallow weather layer produce both features, but only reproduce observed prograde equatorial flow on Jupiter and Saturn under special conditions(5,6). In contrast, deep convection models reproduce equatorial superrotation, but lack coherent vortices(7-11). Here we combine both approaches in a three-dimensional simulation where deep convection grades into a stably stratified shallow layer. We find that steady zonal jets are driven by deep convective flows, whereas anticyclonic vortices form where upwelling plumes impinge on the shallow layer. The simulated vortex circulation consists of cool anticyclones shielded by warm downwelling cyclonic rings and filaments, in agreement with observations and theory(3,12-15). We find that the largest vortices form in westward anticyclonic shear flow nearest to the equatorial jet, similar to Saturn's so-called storm alley(16) and Jupiter's Great Red Spot. We conclude that vortices have a deep origin in gas giant atmospheres.