Targeted NOAA FY24 competition (#3167175): CVP advancing understanding of ocean variability and change in support of noaas climate ecosystems fisheries initiative introduction to the problem:…

This federal Cooperative Agreement award from the National Oceanic and Atmospheric Administration (NOAA) under the Climate and Atmospheric Research program (CFDA 11.431) provides $699,339 to the University of California, Irvine (UC Irvine) to study the characteristics, drivers, and ecosystem impacts of marine heatwaves and compound extreme events in the Northwest Atlantic ocean.

The project will apply water mass transformation theory to understand the three-dimensional structure and evolution of these extreme oceanic events, using both NOAA's new regional ocean model as well as observational data. UC Irvine will collaborate with a co-investigator from the Massachusetts Institute of Technology (MIT) who will oversee the analysis of marine heatwaves, water mass transformations, and marine ecosystem impacts. The research aims to improve scientific understanding of these climate-driven extremes and their effects on marine ecosystems, which can inform NOAA's climate adaptation and fisheries management efforts.

Targeted NOAA FY24 competition (#3167175): CVP advancing understanding of ocean variability and change in support of noaas climate ecosystems fisheries initiative introduction to the problem: extreme events in the ocean, such as marine heatwaves (MHWS), biogeochemical extremes (e.g. hypoxia), and compound extremes (CEX) pose a challenge for marine ecosystem and fisheries management, especially as the frequency and intensity of these events change as the climate warms. Much of the MHW literature defines these events as prolonged local exceedances of a statistical threshold using only sea surface properties and applies ad-hoc diagnostics such as mixed layer budgets to understand their drivers. Rationale: a more integrative view of MHWS and other extreme events as time-evolving three-dimensional water volumes is needed. Water mass transformation (WMT) theory provides a framework to understand the growth and decay of such water bodies in terms of closed budgets. IT allows for attributing changes in the volume of an extreme event to physical processes that drive IT, generalizing the one-dimensional mixed layer approach to three-dimensions. Brief summary of work to be completed: we propose to apply WMT theory to understand the characteristics, drivers, and ecosystem impacts of coherent MHW, biogeochemical extreme, and CEX events in the northwest atlantic (NWA). We will apply these methods to both NOAA gfdls new eddy- and tide-resolving regional hindcast simulation of the NWA and various NOAA-supported observational platforms, which will be used to evaluate the models fidelity. First, we will use an object identification algorithm to characterize the three-dimensional and time-evolving structure of recent coherent MHW events. Second, we will extend this analysis to biogeochemical extreme and multi-stressor CEX events. Third, we will apply WMT theory to isolate diabatic physical processes that drive MHW evolution. Finally, we will quantify the impacts of MHW and CEX events on marine ecosystems, as represented in chlorophyll, net primary production, and community structure. Broader impacts and relevance to the competition and NOAA: this project will directly advance noaas mission and address the competitions priorities by improving understanding of the characteristics, drivers, and impacts of oceanic extremes. Our evaluation of modeled VS. Observed extremes will lay a foundation for predictability studies and model improvement. The wmtframework will isolate processes that materially warm waters from those that simply move existing heat around. IT will be particularly useful for analyzing output from noaas new eddy- and tide-resolving simulations, which are dominated by aliasing of reversible adiabatic variability. The PIS will coordinate with the marine ecosystems task force to package the results to be most usable by fisheries managers. This project will support, directly, the training of a postdoc and, indirectly, the mentoring of a climate justice fellow working on a synergistic already-funded project. Research results will be shared through public data archives, open-source software, K-12 outreach talks, conference presentations, and peer-reviewed publications.