Auroral stratospheric jets in Jupiter
Résumé
The cloud-top zonal wind of Jupiters atmosphere is a superimposed eastward and westward winds structure with velocity peaks of up to 150 m/s around the equator. In the stratosphere, there are no tracers such as clouds to directly measure the dynamics in the visible range. With the ALMA interferometer we mapped Jupiters stratospheric emission in HCN(4-3) at very high spectral and spatial resolutions. These observations allow us to retrieve the stratospheric winds from the Doppler shifts observed on the spectral lines. We detect zonal winds of up to 200 m/s around the equator, and non-zonal winds with speeds of 300-400 m/s in the polar regions that appear colocated with the auroral ovals. In the southern polar region, we find that these non-zonal winds, form a vortex that seems to be lying under the southern auroral main oval. This stratospheric auroral vortex may be the lower extension of the 1-2 km/s ionospheric supersonic jets as seen in the infrared.