New research helping to understand oxygen dynamics in the Atlantic Ocean

September 6, 2023

The ocean is home to many ecosystems and life on Earth. It houses amazing creatures of all shapes and sizes, from whales and dolphins, down to the tiniest plants which produce oxygen for us to breathe. The ocean breathes and changes too, with processes like photosynthesis, ocean circulation, and air-sea oxygen exchange playing important roles in maintaining the oxygen levels within the ocean itself.

As the oceans are warming, it is becoming even more important to understand how these processes work and how they might continue to evolve within our changing climate.

Lauren Moseley, a Ph.D. student at Columbia University, is conducting research focused on using ocean observations to improve how ocean models simulate oxygen uptake, production, and circulation. Completing her OFI Visiting Fellowship, Lauren is working with Dalhousie scientists Dariia Atamanchuk, Jannes Koelling, and Doug Wallace to better understand how models and observations can help each other.

Lauren in Halifax Harbor during the Dalhousie-led OAE dye-tracing study

The challenges in monitoring long-term ocean patterns

Currently, researchers study ocean oxygen using both observations and models.

Observational campaigns have been used to better outline the different components of ocean oxygenation, but historically tend to be expensive and difficult to coordinate, as Lauren discussed. This often means that only specific snapshots of the oxygen cycle in space and time are collected, making it difficult for researchers to see the full picture and establish long-term patterns.

This is where numerical ocean models have been used in the past, they are able to fill in the observational gaps by using mathematical equations which can produce expansive simulations. However, this does not come without its own disadvantages. “Generalized equations do not represent all parts of the ocean equally well,” said Lauren. ”Especially in regions with more complex physical dynamics like in the Labrador Sea.”

“[We need to make] sure that we're correctly understanding mechanisms through direct observations, but also trying to fill in gaps where we can through well-validated numerical equations,” says Lauren.

Understanding the ocean’s complexities

The subpolar region of the North Atlantic Ocean, which includes the Labrador Sea – Lauren’s primary area of study – is one of the only areas of the global ocean where deep water formation occurs. The strong surface winds cause deep mixing which subducts oxygen-rich surface waters to great depths, making this region of the ocean critical to setting the global ocean oxygen inventory.

In her PhD, Lauren has focused her research mainly on one data-assimilative model that reconstructs nearly two decades of Atlantic Ocean physics and biogeochemistry.

“I have been working with Dalhousie researchers this summer to further bring that model into alignment with observations,” says Lauren. “When you compare model simulations against in-situ data, you start to see where the model is underperforming… and, more excitingly, where the model is capturing real-world dynamics properly.”

Lauren on a GO-SHIP research cruise across the North Pacific

The future of ocean oxygenation

Improving the mechanistic understanding of oxygen uptake, production, and circulation will allow scientists to better predict oxygen distribution. “This helps us to better identify and address the growing trends in oxygen depletion which has huge impacts [on] marine ecosystems and biodiversity,” says Lauren.

Lauren’s ultimate goal is to bring the ocean observing and modelling communities into closer communication to best tackle challenges brought on by climate change. Lauren hopes to bring a more holistic perspective to the community of scientists striving to tackle the same questions but with different approaches.

“I'm so motivated in this present moment to contribute what I can to our collective understanding of ocean oxygen dynamics, which is just one piece in the puzzle as we prepare for worsening ocean conditions and global climate conditions at large,” says Lauren.