The equatorial wind structure in Jupiter’s stratosphere from direct wind and temperature measurements with ALMA and IRTF/TEXES

Since 30 years, an equatorial oscillation of the temperature structure with a quasi-period of 4 years has been discovered in the atmosphere of Jupiter (Orton et al. 1991, Leovy et al. 1991). This phenomenon results in a complex vertical and horizontal structure of prograde and retrograde jets. However, the wind structure of the stratosphere in the equatorial zone of Jupiter has not been measured directly. It has only been inferred in the tropical region from the thermal wind balance using temperatures measured in the jovian stratosphere and the cloud-top wind speeds measured as a initial condition (e.g. Flasar et al. 2004). But temperatures are not constrained between the upper troposphere and the middle stratosphere from observations, limiting thus the accuracy of the thermal wind balance.

In this study, we derive self-consistently for the first time the structure of the tropical winds by utilizing wind and temperature observations all performed in the stratosphere. The wind speeds were obtained by Cavalié et al. (2021) at 1 mbar in Jupiter's stratosphere in both the equatorial and tropical regions in March 2017 with ALMA. The stratospheric thermal field was measured a few days before from the equator to the mid-latitudes with Gemini/TEXES (Giles et al. 2020). For the derivation of the wind, we use both the thermal wind equation (Pedlosky 1979) and the equatorial thermal wind equation (Marcus et al. 2019). In this paper, we will present and discuss our results.