Using a novel combination of autonomous vehicles for air-sea interaction studies: Results from the Eurec4a campaign

The Tropical North Atlantic region is a key driver of climate variability and extreme weather events, driven largely by heat and momentum exchanges across the air-sea boundary. Observations of these fluxes by satellites and vessels are limited in their spatial resolution and length of time series respectively. In-situ samples across long time periods are needed, which can be obtained through developing a network of in-situ flux measurement platforms. UEA and AutoNaut have worked to address this challenge with the deployment of Caravela - an AutoNaut uncrewed surface vessel. Caravela is a wave and solar powered autonomous vessel, equipped with meteorological and oceanographic sensors and the ability to transport a Seaglider. Caravela successfully completed its first scientific deployment as part of the Eurec⁴a campaign. 

Eurec⁴a ran from January—March 2020 from Barbados, investigating climate change feedback in the Tropical North Atlantic and the role of cloud systems. Caravela spent 11 days of her 33-day deployment occupying a 10 km square, co-located with other Eurec⁴a platforms to gather in-situ surface data on heat and momentum exchange. Preliminary results from Caravela give us an insight into heat exchange at the surface, downwelling radiation and wind conditions during deployment. There is an identifiable diurnal cycle during the deployment, particularly visible in temperature data, which will feed into our understanding of changes in fluxes at a local scale. Profiling ocean gliders at the study site allow us to determine a time series of upper ocean heat content changes. These data, alongside that collected by other platforms during Eurec⁴a, should enable an upper ocean heat budget to be calculated at Caravela’s study site.