Constraints on the latitudinal profile of Jupiter's deep jets
journal contributionposted on 10.06.2021, 12:48 by E Galanti, Y Kaspi, K Duer, L Fletcher, AP Ingersoll, C Li, GS Orton, T Guillot, SM Levin, SJ Bolton
The observed zonal winds at Jupiter's cloud tops have been shown to be closely linked to the asymmetric part of the planet's measured gravity field. Here, we examine to what extent, and at which latitudes, must the flows at depth resemble those at the cloud level to match the gravity signal. We show, using both the symmetric and asymmetric parts of the measured gravity field, that the observed cloud-level wind profile between 25°S and 25°N must extend unaltered to depths of thousands of kilometers. Poleward, the midlatitude deep jets also contribute to the gravity signal, but might differ somewhat from the cloud-level winds. We analyze the likelihood of this difference and give bounds to its strength. We also find that to match the gravity measurements, the winds must project inward in the direction parallel to Jupiter's spin axis, and decay inward in the radial direction.
Plain Language Summary
Observations of Jupiter's cloud-tops reveal very strong atmospheric winds reaching 500 km/hr. Using very accurate measurements of the planet's gravity field, provided by NASA's Juno spacecraft, the cloud-level winds were found to extend thousands of kilometers into the interior of Jupiter, with a wind profile similar to that observed at the clouds level. However, analysis of various measurements suggested that at some latitudinal regions the flow below the clouds might be different to some extent. Here we explore the constraints posed by the Juno gravity measurements on the latitudinal profile of the zonal flow in Jupiter below the cloud level. We find that to explain the detailed latitudinal structure of the wind-attributed gravity field, the cloud-level winds in the 60°S–60°N range have to extend deep into the planet, approximately keeping their observed latitudinal profile. With that, we find that most of the wind-induced gravity signal comes from the 25°S to 25°N region, where the strongest jets reside, suggesting that in the midlatitudes the observed jets at the cloud level might be somewhat different at depth.