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A Month at Sea: Insights from Research Cruises in the Subpolar North Atlantic

24 September 2024

PhD graduate Dr Jack Wharton tells us about his voyage on the CROSSROAD24 research cruise, exploring the subpolar Northwest Atlantic.

CTD sampling - Jack Wharton sub-sampling seawater from bottles on the CTD. Photo credit: Simon Wett, University of Hamburg

Dr Wharton's journey provided invaluable insights into the Atlantic Meridional Overturning Circulation (AMOC) and its impact on our climate.  

The main aim of this cruise was to gather new hydrographic data from the Flemish Cap, a submarine plateau in the Northwest Atlantic Transition Zone.  

Jack and his team aimed to collect temperature, salinity, and oxygen measurements to better understand the region's complex ocean circulation patterns.  

These data will be fed into high-resolution climate models to enhance our understanding of the AMOC and its critical role in Earth's climate system. 

Dr Wharton was part of a three-person team operating a CTD (Conductivity, Temperature, Depth) device, which measures various oceanographic properties at depths of up to five kilometres.  

By lowering the CTD from the vessel, they were able to record temperature, salinity, and oxygen concentrations, as well as collecting seawater samples for further analysis. He noted, "This experience has given me a deep respect for the work involved." 

One significant challenge the team encountered was Hurricane Ernesto, which threatened their work area with waves forecast to reach 10-12 metres high.  

It took the captain sailing the ship 36 hours north to avoid the worst of the storm and ensure the safety of Jack and the rest of the crew.  

Expected storm track of Hurricane Ernesto. Jack is pointing out where the boat is located 12 hours before the storm is due to arrive at Flemish Cap.

Reflecting on the conditions at sea, Dr Wharton said, "As a paleoceanographer, I frequently use hydrographic data, but I had no idea of the great lengths required to collect it."  

He saw how the surface ocean around the Flemish Cap fluctuates between warm, salty waters flowing northward and cold, fresh waters moving southward.   

"The fronts between these water masses were much sharper than I had anticipated—so much so that within just 10 km, the conditions could completely change!" 

Dr Wharton's research is part of the broader EPOC project, which involves 21 institutions working to redefine our understanding of the AMOC and its implications for weather and climate.  

The voyage, along with his post-doctoral work, has contributed important data needed to achieve EPOC's ambitious goals.  

In total, Jack spent a challenging 28 days at sea, to which his main take-home thought was, "Next time I’d definitely bring more snacks!"  


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