The restless soul of the planets

Researchers from the Department of Civil, Constructional and Environmental Engineering of Sapienza University of Rome in a team with other universities (Oxford, UAE, and USF) have developed a theory to measure the turbulence of the giant planets. The study, published on the journal Geophysical Research Letters, shows that turbulence on Jupiter’s atmosphere is four times more intense than Saturn's

The images of Jupiter and Saturn from Cassini show highly turbulent storms, swirling clouds and persistent structures, a well-known example being the Great Red Spot of Jupiter. These are the manifestations of an intense turbulent activity in their atmospheres powered by solar energy and by a heat flux from within the planet itself.

Turbulence is associated with a non-linear energy transfer between the different scales of the motion known as energy cascade; in this case, the energy transfer occurs mainly towards the larger scales of the motion and originates the intense flows observed in the atmospheres of the planets. Quantifying the energy transfer appears therefore to be crucial for characterizing planetary turbulence. A new research carried out at the Department of Civil, Building and Environmental Engineering of Sapienza has identified a possible method to measure the turbulent activity of planets as Jupiter and Saturn. The work was funded under the MARIE SKŁODOWSKA-CURIE ACTIONS Individual Fellowships programme and recently published on Geophysical Research Letters.

"Given the lack of large quantities of spatially and temporally resolved data, quantifying planetary turbulence seems to be inaccessible to conventional tools − say Stefania Espa and Simon Cabanes. Our research shows how it is possible to estimate turbulent energy transfer using a universal method based on a quantity that is relatively easy to calculate with the available data, the potential vorticity (PV, the ratio between absolute vorticity and fluid thickness)."

The method described in the study was tested both with real data from Jupiter and Saturn as well as with data obtained from laboratory experiments and numerical simulations. "We have verified the consistency of our method − concludes Stefania Espa – and shown for the first time that the energy transfer in Jupiter’s atmosphere is four times more intense than Saturn’s."

References:

Revealing the intensity of turbulent energy transfer in planetary atmospheres – Simon Cabanes, Stefania Espa, Boris Galperin, Roland M. B. Young, Peter L. Read – Geophysical Research Letters, 2020. DOI https://doi.org/10.1029/2020GL088685