The University of Alcalá will measure on a fiber optic cable in the Strait of Gibraltar

The Strait of Gibraltar is an area of great interest for seismic and oceanographic monitoring, both due to its exceptional location and the information it can provide on geophysical processes that occur in the area. The dynamics of the sea in this area is unique and gives rise to phenomena of great geophysical interest, such as internal waves.

Internal waves are generated fundamentally from the interaction of the tide with variations in the profile of the submarine floor, and are of great importance in the processes of mixing water in the ocean, which in turn have a great impact on all the phenomena of climate change. Although they are barely visible from the surface, internal waves in the sea can reach amplitudes much greater than surface waves, sometimes exceeding 100 meters in amplitude. These phenomena have an impact on multiple environmental variables ranging from the temperature of the Mediterranean to the biological processes that occur in the environment.

Thanks to the chirped pulse Distributed Acoustic Sensing (DAS) technology, developed by the Department of Electronics of the University of Alcalá and Aragón Photonics, and the 'Dos Continentes' cable of the Gtd España, which runs between Tarifa and Ceuta, these processes will be able to be monitored with an extremely high resolution, certainly never seen before.

The technology that will be deployed in the Strait cable will monitor variations in water temperature every 10 meters of fiber cable, with a resolution of one thousandth of a centigrade degree. These data will provide invaluable information on how these phenomena occur and their consequences on the mixing of water between the coldest and hottest layers of the sea.

It is expected that the data collected will be useful for a multitude of subsequent works, from basic studies of the propagation of these waves in the sea and in the quantification of their broader implications both in aspects such as climate change and more local studies related to the dynamics of the populations of living beings that inhabit these ecosystems.

The data will also be used in the framework of the PSI project (reference PLEC2021-007875), funded by the Ministry of Science and Innovation and the NextGenerationEU/PRTR program of the European Union. This project aims to develop an intelligent monitoring system based on DAS technology that allows preventing damage to the fiber optic cable itself, through early warning of potentially harmful activities. The measurements will serve to obtain a database of acoustic signals produced by ships in the environment.