Two researchers from the UPC’s ESEIAAT simulate polar storm formation on Saturn

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From left to right: Enrique García and Manel Soria

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Polar storm on Saturn in 2018. The top panel shows a Hubble Space Telescope image of the planet, taken on 6 June 2018. Numbers 1 and 2 in the box on the North Pole mark the two main storms, which are shown as white clouds. The upper part of the bottom panel shows these two storms as observed by the space telescope represented on a planisphere, and the lower shows the computer simulation of their interaction

The research is part of an international scientific collaboration that has observed multiple storms at different latitudes on the second largest planet in the solar system

Nov 21, 2019

The researchers Enrique García and Manel Soria, from the Terrassa School of Industrial, Aerospace and Audiovisual Engineering (ESEIAAT) at the Universitat Politècnica de Catalunya · BarcelonaTech (UPC), have developed a numerical model to simulate the evolution of polar storms on Saturn and identify the conditions that caused them. The study has been published in Nature Astronomy and is part of an international project led by the researcher Agustín Sánchez Lavega, from the University of the Basque Country (UPV/EHU), which has also involved other researchers from the same university, the Cassini space mission, the Hubble Space Telescope and a whole network of scientific observers.

Like other planets with an atmosphere, Saturn is a natural laboratory where it is possible to study the meteorological phenomena that take place on our planet and to test out, under extreme conditions, the models used to explain and predict them.

Now, the researchers Enrique García and Manel Soria, from the UPC’s ESEIAAT, have created a numerical model to evaluate and simulate the evolution of polar storms on Saturn and the energy involved, and compare them to other types of storms observed so far.

This has allowed, for the first time, to identify multiple storms at different latitudes that burst as a result of convection in the deep water clouds about 200 km below the visible clouds on the ringed planet. The hot, humid gas rises forcefully in Saturn’s hydrogen atmosphere and forms dense clouds of ammonia that are visible through a telescope.

Enrique García and Manel Soria are professors at the ESEIAAT and researchers from the UPC’s Turbulence and Aerodynamics in Mechanical and Aerospace Engineering Research Group (TUAREG), and are part of an international group of scientists who are studying the atmospheric phenomena on Saturn. The project has involved the Cassini space mission of NASA and the European and Italian space agencies—which was orbiting the planet until September 2017—, the Hubble Space Telescope, the UPV/EHU’s PlanetCam camera installed at the Calar Alto Observatory, the numerical simulations by the UPC and a whole network of amateur observers who provided the images for monitoring the phenomenon on a day-to-day basis.

Mysterious spots on Saturn
It all started on the night of 29 March 2018, when a Brazilian amateur astronomer captured on telescope a brilliant white spot on the disc of the planet Saturn close to its north pole. A few days later, the spot became bigger, reaching a length of about 4,000 km and becoming the most noteworthy detail on the disc of the ringed planet. Two months later a second spot appeared further north on the planet, and sequentially over subsequent months, a third and fourth spot, which were much closer to the polar region, on the edge of the famous Saturn hexagon, a phenomenon that had never been previously observed.

The spots drifted throughout all these months at varying speeds, dragged along by the atmospheric winds that blow on Saturn like jet streams eastwards and westwards. While the first spot, located further south, drifted eastwards at a speed of about 220 km/h, the one located further north drifted at about 20 km/h westwards. This led to encounters between them, and in the course of their mutual interaction they generated atmospheric disturbances that spread throughout Saturn’s polar region.

Agustín Sánchez Vega, the UPV/EHU scientist who is leading the study, said: “It is the first time that we have seen multiple storms at different latitudes simultaneously. To date, we had seen isolated storms that were either small or gigantic”.

On Earth, storms like this last a few days at the most, but on Saturn the first of all the spots remained active for more than seven months”, Sánchez Lavega added. “What is more, the new storms have only been observed in the northern hemisphere—they have never been spotted in the south—and seem to have been in line with their formation rate of one every 30 to 60 years”.

Agustín Sánchez Lavega, a professor of Physics at the UPV/EHU, the director of the Grupo de Ciencias Planetarias and a 2016 Euskadi Award for Research winner; UPV/EHU Jon Legarreta, Ricardo Hueso and Teresa del Río Gaztelurrutia; and Santiago Pérez, a researcher and PhD holder from the same research group, participated in the discovery. Enrique García and Manel Soria are professors from the UPC’s Department of Physics, within the Aerospace Engineering Division at the ESEIAAT, and members of the Turbulence and Aerodynamics in Mechanical and Aerospace Engineering Research Group (TUAREG).