264 — Jupiter’s atmospheric jet streams extend thousands of kilometres deep

Kaspi et al (10.1038/nature25793)

Read on 11 May 2018
#jupiter  #NASA  #atmosphere  #jet-stream  #juno  #gravity  #space  #gravity-harmonics 

When you picture of Jupiter in your head, you probably picture very characteristic things: The Great Red Spot, and the alternating bands of color that form turbulent belts across the planet’s surface.

It has long been questioned how deep these bands are: How far do they reach down from the atmospheric surface into the gas giant?

The Juno spacecraft has been orbiting Jupiter since 2016, and from this rich and long-term dataset, the authors determined that the jet streams — those beautiful colorful bands — only extend about 3000 kilometers into Jupiter’s atmosphere.

Furthermore, the same gravity measurements also indicated that there was north/south asymmetry in Jupiter’s gravitational field, which, in a gas giant planet like Jupiter, directly correlates with the magnitude of atmospheric dynamics.

From this measurement of atmospheric dynamics, we can also determine how much of Jupiter’s mass is taken up by dynamic atmosphere: It appears to be about 1% of Jupiter’s total mass.

These results are derived from the measured gravitational harmonics according to Juno’s sensors. I’ve now spent about 30 minutes trying to figure out what gravitational harmonics are and I’m coming up short (I think because Laplacians are something I also have never understood, and another 30 minutes are probably not going to do it). BUT: The incremental harmonic functions represent the influence of a gravitational field in 3D space (just as they represent the probability-fields for electrons orbiting the nucleus of an atom).