July 23, 2018

Mapping Ocean Fronts with Robotic Fleets

Led by Dr. João Borges de Sousa of the Laboratório de Sistemas e Tecnologia Subaquática (LSTS) of Portugal, a multinational, multidisciplinary team of scientists have designed, built, and deployed seven autonomous underwater vehicles (AUVs) in the North Pacific Subtropical Ocean Front using the Schmidt Ocean Institute’s research vessel Falkor.

Ocean fronts are areas where drastic changes occur in the properties of waters. These changes are of interest to scientists studying Earth’s climate and marine ecosystems. The particular ocean front examined by the teams is situated about 1,000 nautical miles SW of Southern California. It’s here that less dense and cold waters coming from the Arctic meet the otherwise saline waters of the Pacific.

Three scout ASVs (autonomous surface vehicles) were sent to detect the ocean front ahead of the Schmidt Ocean Institute expedition. The area was then mapped for three weeks by a fleet of AUVs, UAVs (unmanned aerial vehicles) and the R/V Falkor.

In order to map the 3D structure of this dynamic front, the AUVs cycled in a ‘saw-tooth’ pattern between the water’s surface at a depth of 100 meters. The AUVs were controlled from either the R/V Falkor or across the world from an ocean space center in Portugal, with commands sent via RockBLOCKs and the Iridium network.

Operating 24/7, the AUVs would also periodically upload preliminary sensor data, like temperature, salinity, chlorophyll, and turbidity profiles (water properties at different measured depths).

When interesting features would appear, UAVs were deployed to measure the same features from the air using thermal and multispectral cameras. This feat wouldn’t have been possible using only traditional marine/aerial vehicles, due to the logistical and financial restrictions involved with these larger assets.

In less than three weeks, the AUVs traversed over 1,000 nautical miles, operating approximately for 500 hours and sending over 12,000 transmissions – or 2.5 megabytes of Iridium data – to researchers via Rock Seven (now trading as Ground Control)’s servers.

The mission’s success proves that lower-cost, autonomous, and connected vehicles can play a key role in collecting abundant data sets from remote locations. This allows research vessels like the R/V Falkor to shift their role from being a primary sampling unit to a command center, reducing operational costs while increasing scientific knowledge.

Iridium connectivity also allowed the replica command center based in Portugal to take over the second shift, giving scientists round the clock control of their research assets.

More information about this research can be found in the Schmidt Ocean Institute’s expedition page.

All photos (c) Schmidt Ocean Institute / LSTS.

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