OCE PRF Track 2 (International): Tracking mesopelagic carbon flux and particle size on a multi-ocean scale using a fleet of bio-optical profiling floats

Briggs Nathan, Walpole ME

Investigators

Abstract

The sinking of organic carbon through the mesopelagic ocean (100-1000 meters) represents an important long-term sink for atmospheric carbon dioxide and a carbon source for deep-sea and benthic ecosystems. Research results from this project will make a significant contribution to the science of carbon flux, which is important both for improving climate projections and understanding deep ecosystems. The project was submitted to the Ocean Sciences Postdoctoral Research Fellowship program and will further the career of a promising scientist. Given the global nature of studying carbon flux in the mesopelagic, the fellow is being hosted by Hervé Claustre at the Laboratoire d'Oceanographie de Villefranche(LOV) in France and building strong international collaborations to improve understanding on this internationally important topic. This award was supported with funding from the Office of International and Integrative Activities. Temperate and subpolar phytoplankton blooms account for large amounts of mesopelagic carbon flux. Mesopelagic flux patterns may change considerably in the future due to climate change, potentially causing climate feedbacks and/or threatening deep ecosystems. Current technologies for measuring mesopelagic flux are logistically challenging, involving the retrieval of physical samples. Current methods are also difficult to compare, due to differing sampling scales and methods. In this project, the fellow will increase coverage of mesopelagic flux measurements during high-latitude phytoplankton blooms by applying novel methods the fellow developed during graduate studies to a large "Bio-Argo" float dataset. The flux dataset produced as a result of this project will be of great benefit to the scientific community, allowing broad analysis of global patterns in addition to the intensive, region-specific flux studies undertaken using traditional methods. By identifying broad-scale patterns in flux and their drivers, this work will increase knowledge of the regions studied and help satellite oceanographers and modelers test and improve flux products. Furthermore, as the Bio-Argo fleet expands to form a permanent, global network, this work will form the start of something bigger: a global, in situ flux record. As such, methodological lessons learned during analysis of this project will inform future sampling strategies and validation efforts, helping to ensure the quality of this global record.