How Well Does WOMBAT Capture Export Variability? New Insights from BGC-Argo
Annika Oetjens
Annika Oetjens (1,2), Tyler Rohr(1,2,3), Zanna Chase(1,2) and Peter Strutton(1,2)
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, Australia
- ARC Australian Centre for Excellence in Antarctic Sciences, University of Tasmania,
Hobart, Tasmania, Australia - Australian Antarctic Program Partnership, University of Tasmania, Hobart,
Tasmania, Australia
Understanding the depth-dependent attenuation of particulate organic carbon (POC) is essential for constraining the biological carbon pump and evaluating its role in long-term carbon sequestration. While the Australian biogeochemical model WOMBAT, represents export production, its ability to capture the vertical structure of attenuation, especially seasonal and regional variability, remains uncertain. We apply a broken power law (BPL) framework to POC profiles derived from BGC-Argo float observations across the Southern Ocean, revealing two distinct attenuation regimes with strong ties to net primary production and minimal correlation with temperature. These observations offer a valuable benchmark for assessing model performance.
We explore whether WOMBAT can represent the observed structure in particle attenuation. As current implementations often rely on simplified or uniform remineralisation schemes, this approach highlights potential gaps in resolving mechanisms such as microbial degradation, particle aggregation, and zooplankton activity. Conversely, model experiments can help test hypotheses about ecological or physical drivers not directly observable with floats.
This work will be of interest to researchers working with biogeochemical models like WOMBAT, those evaluating climate-carbon feedbacks, and the growing community using autonomous platforms as observational constraints for model development and validation.
Keywords: BGC-Argo, Southern Ocean, particle attenuation, WOMBAT, carbon export
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