Atlantic to Med: An Historic 5,000+ Nautical Mile Voyage for Science

On July 17, 2020, two Saildrone unmanned surface vehicles (USVs) known as SD 1030 and SD 1053 completed the first-ever Atlantic to Mediterranean mission. This historic nine-month voyage began in Cabo Verde, off the coast of West Africa, entered the Mediterranean Sea through the Strait of Gibraltar, and finished in Trieste, at the top of the Adriatic Sea.

The distance from deployment to retrieval, as the crow flies, was more than 5,000 nautical miles (9,260 kilometers or 5,754 miles). However, SD 1030 and SD 1053 actually sailed a combined distance of some 15,015 nautical miles (27,810 kilometers or 17,280 miles).

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The mission was a public-private partnership between Saildrone and 12 oceanographic research institutions and universities from seven countries. The mission was conducted in two phases: Phase 1 was an eddy survey near Cabo Verde led by the Helmholtz Centre for Ocean Research (GEOMAR) based in Kiel, Germany, and Phase 2 focused on cross-calibration of CO2 measurements at fixed ocean stations led by the Integrated Carbon Observation System, Ocean Thematic Center (ICOS OTC) based in Bergen, Norway. 

Researchers from Ocean Science Centre Mindelo (OSCM), The Oceanic Platform of the Canary Islands (PLOCAN), Balearic Islands Coastal Observing and Forecasting System (SOCIB), Instituto Hidrográfico (IH), Sorbonne Université’s Laboratoire Océanographique Villefranche (LOV), Le Centre Nationale de la Recherche Scientifique (CNRS), Istituto Nazionale di Oceanografia e Geofisica Sperimentale (OGS), Istituto di Scienze Marine del Consiglio Nazionale delle Ricerche (CNR-ISMAR), and Istituto sui Sistemi Intelligenti per l'Automazione del CNR (CNR-ISSIA) ran regional sub-missions, including comparisons with moorings, gliders, and other assets.

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“This was an incredibly ambitious mission that posed numerous challenges along the way. The ~5,000-nautical mile voyage had to deal with rapid marine growth in tropical waters, crowded shipping lanes in the Strait of Gibraltar, light winds, strong currents, transiting nine different EEZ’s and interacting with six different navies. However, despite the challenges, we’re thrilled to announce that both vehicles have now arrived in Trieste, having completed all of the mission’s primary and secondary objectives,” said Saildrone founder and CEO Richard Jenkins. 

“The COVID-19-transformed world they find upon arrival in Trieste is a very different place than they set sail in back in October, but they sailed on, unaffected by what was going on in the world around them. This voyage has been a great demonstration of the resilience of unmanned systems to continue essential ocean science during troubled times,” Jenkins added.

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Mission highlights

The saildrones were deployed from the Canary Islands in October 2019 and transited south to Cabo Verde, off the west coast of Senegal, where they participated in the #MOSESeddyhunt, a multicomponent field study involving a team of chemists, biologists, and physicists on board the German research vessel Meteor and a variety of surface and underwater autonomous vehicles, floats, drifters, and an airplane. The saildrones were used to scout for ocean eddies and to conduct high-resolution surveys of certain aspects of the eddies.

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Once the eddy survey was completed, the saildrones moved on to the second phase of the mission collecting data at nine fixed ocean stations for cross-calibration and validation: CVOO (Cabo Verde), ESTOC (Gran Canaria), LION (France), ANTARES (France), DYFAMED (France), W1M3A (Italy), E2M3A (Italy), PALOMA (Italy), and Miramare (Italy).

On their way to the Mediterranean Sea, the saildrones sailed several laps around MONIZEE, Portugal's oceanic buoy station managed by the Instituto Hidrográfico.

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Escorted by a patrol boat from the Spanish Armada and a research vessel from the University of Cadiz, SD 1030 and SD 1053 sailed through the Strait of Gibraltar to enter the Mediterranean Sea—the first autonomous wind-powered vehicles to do so. They then headed north toward Spain’s Balearic Islands to perform a sub-mission in partnership with SOCIB, which included monitoring oceanographic conditions in the area of a tagged sea turtle navigating near the strong anticyclonic eddy south of Ibiza.

From there, the saildrones headed toward the French EEZ for a saildrone-glider inter-comparison study along the Nice-Calvi Line in partnership with LOV.

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Working with OGS, the saildrones completed several sub-mission objectives in the Tyrrhenian and Adriatic Seas. They collected data about potential CO2 emissions to estimate CO2 air-sea exchanges in an area of volcanic activity around the Aeolian Islands before circumnavigating Sicily entering the Adriatic Sea through the Strait of Otranto. They collected data near the E2M3A ocean station over the South Adriatic Pit and completed a saildrone-glider inter-comparison study along a transect extending from Italy to Croatia before heading north toward the Gulf of Trieste to complete the final objectives of the mission.

Throughout the mission, the ICOS OTC data group helped with processing the carbon data and forwarding it to the ICOS data portal (click to view SD 1030 data or SD 1053 data) and Copernicus in near real time.

“We’re grateful and happy for the cooperation with Saildrone. The team was very helpful and solutions-oriented, which was important for such a long-lasting mission as ATL2MED. We were also quite impressed by the amount of effort they put into piloting the saildrones—do they ever sleep?!” remarked Dr. Ingunn Skjelvan, a research scientist at NORCE Norwegian Research Centre and Bjerknes Centre for Climate Research, and principal investigator for station certification at ICOS.

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The two last fixed ocean stations visited by the saildrones were the ICOS stations PALOMA and Miramare (MAMBO1). Paloma is located in the Gulf of Trieste and Miramare is right off the coast of Trieste in the Miramare Marine Protected Area, the first marine nature reserve created in Italy, in 1986, and home to a rich biodiversity of marine organisms. Importantly for surveying in such fragile marine areas, saildrones are powered by the wind for forward propulsion and solar energy to run the onboard instruments. They carry no pollutants, no fuel, emit no discharge, and, as sailing vehicles, they are silent and unobtrusive.

The Gulf of Trieste is an area subject to riverine inputs and strong seasonal variations —more than 20°C from winter to summer—that strongly affect the variability of the CO2 system. During the winter, the North Adriatic Dense Waters contribute to the physical pump that absorbs CO2 and transfers it to deeper waters. 

“A better understanding of these processes is important for evaluating the potential impact of coastal acidification in the region, and the data may also help address the spatial variability of CO2 air-sea exchanges in an area affected by riverine discharges,” said Dr. Michele Giani, a senior researcher at OGS responsible for the Miramare station. “Our research is based on the measurements at fixed points, therefore all the data that contributes to measuring spatial variability around our stations can contribute to improving understanding of which processes are best detected at the observational sites. The data will be integrated into our ongoing research of the drivers of the carbonate system temporal variability in the northern Adriatic Sea.”

Click here to download the data from the ATL2MED mission in NetCDF format.

Next steps

The Mediterranean Sea is considered to be a small-scale ocean in which many of the processes found throughout the world’s oceans occur, making it especially interesting for physical, climatic, and environmental studies. It is a highly productive region, much more so than anticipated, requiring a couple of service stops throughout the mission, despite the use of the latest anti-biofouling technology. The mission took nine months from start to finish and will serve as a blueprint for how public and private institutions between nations can work together to advance ocean observations.

“The level of productivity of the Mediterranean was a surprise, but the speed and efficiency of the pit stops we made in Cabo Verde, France, and Italy are a testament to the fantastic international collaboration of this mission—especially with the added challenge of the COVID-19 pandemic,” said Saildrone COO Sebastien de Halleux. “Now the team will be working hard to ensure this series of observations is continued over time supported by funding from public and private sources.”

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Dr. Skjelvan said that for ICOS OTC, the use of the saildrones as validation platforms was the most useful part of the mission: “The CO2 validation data collected will help us certify the fixed stations within the ICOS European infrastructure project. A certified station provides data of the highest possible quality, and thus, underpins the main goal of ICOS. But it’s important to mention that the additional data collected during this mission is incredibly useful for the scientific community as it contributes to our process of understanding the ocean and air-sea interface.”

Saildrone is grateful for the support of its sponsor and scientific collaborators on this remarkable mission. Saildrone would also like to say a special thank you to the Spanish Armada for escorting SD 1030 and SD 1053 through the Strait of Gibraltar and numerous local authorities who assisted with retrieving and servicing the vehicles along the way, especially when Saildrone staff was unable to travel. We would also like to thank the Italian Navy and the Harbormaster’s Office in the Port of Trieste for their collaboration and surveillance of the saildrones during their presence in the Gulf of Trieste, as well as the Port Authority, which has provided a berth for the saildrones upon mission completion.

Despite COVID-19 travel restrictions, Saildrone has continued to operate several missions in the Atlantic and Pacific, including the Alaska pollock survey in the Bering Sea for NOAA Fisheries and Saildrone’s first bathymetry mission in the Arctic in collaboration with TerraSond on behalf of NOAA’s National Ocean Service (NOS).

ATL2MED was an open-data effort generously sponsored by PEAK6, a private technology and investment firm started by Jenny Just and Matt Hulsizer. Atmospheric and oceanographic data will be available to the public on Saildrone’s data portal data.saildrone.com and/or on the European Marine Observation and Data Network (EMODnet) and Surface Ocean CO₂ Atlas (SOCAT). We encourage scientists, researchers, and students to download and analyze these data sets. If you have used Saildrone data for a published paper or if you would like to provide feedback about data quality, please contact us at data [at] saildrone.com.

See all ATL2MED news: https://www.saildrone.com/tag/atl2med‍

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Click to expand and download the map of 2019-2020 ATL2MED mission highlights and overview of the carbon data.‍‍