The experiment: miniature Ionian Sea to understand Sea vortex phenomena

An international group of oceanographers will create a miniature Ionian Sea in a pivoting tank of 13 meters diameter and a meter deep which rotates in 3 minutes imitating the Earth rotation in one day. The LEGI Coriolis in Grenoble (France), the largest rotating laboratory dedicated to fluid mechanics in the world, will host the experiment which aims to understand why large sea vortex in the Southern part of the Ionian Sea have changed sense of rotation in the past decades.

“The cyclonic and anticyclonic vortexes have been studied extensively and seem to appear due to the alternating water masses in the Adriatic Sea and not to the wind - explains Angelo Rubino, oceanographer at Ca’ Foscari and researcher in the team that conceived and will engineer the experiment. A ‘mechanical’ reproduction of the phenomenon will help us test this theory that could not be entirely explained by observations and numerical models”.

The interaction between the Adriatic and the Ionian Seas will be simulated in the laboratory to better understand the alternating streams in the Ionian Sea and the impact of climate change. The oceans experience indeed long lasting circulation phenomena such as vortexes or fronts, similarly to the atmosphere. Understanding their origin and the trends would allow for a deeper knowledge of climate, as well as of biochemical and biology of oceans.

The research project was submitted to the French laboratory within the European Call for Proposals hydralab by an international team guided by Miroslav Gacic from the National Institute of Oceanography and Applied Geophysics (Ogs) based in Trieste and includes oceanographers from Ca’ Foscari, the University of Zagreb and the Marine Biology Station of Piran. Once selected by a panel of international specialists, the team received the requested funding for six weeks of experimental activities with the support of technicians, and access to sophisticated measurement tools and the rotating tank.

Waters with different densities will run down a channel that reproduces the strait of Otranto in a deeper part of the tank that reproduces the Ionian Sea (as shown in the picture below). The subsequent superficial streams will be measured to understand how in reality dense waters from the Adriatic Sea can shape the vortexes that were seen in the Ionian Sea and their variations.

A calendar year of the real ocean will be covered in 15 hours of laboratory rotations. Throughout the six weeks several experiments will be conducted to include different water densities so as to provide indications on the changes of the phenomenon with changes of environmental parameters.

The experiment will be conducted in 2018. The Ca’ Foscari team will be guided by professor Rubino who has already performed two experiments on fluid dynamics within international projects and laboratories, including “LEGI Coriolis” in Grenoble and SINTEF in Trondheim (Norway).