LiveOcean Model Enhancement

Project Team

Lead Principal Investigator: Parker MacCready, UW

Project Overview and Results

The overall goal of the proposed work is to transition the LiveOcean model to a state of sustainable operations hosted by the Northwest Association of Networked Ocean Observing Systems (NANOOS) Regional Association of U.S. IOOS. LiveOcean is a realistic numerical model of ocean circulation and biogeochemistry for the coastal and estuarine waters of the northern California Current System.

The model has been making daily forecasts since late 2015, with steady improvements to reliability, resolution, biogeochemistry, forcing fields, and delivery of results to stakeholders. The model has a well-established and growing group of stakeholders including commercial, tribal, and recreational shellfish and crab fishers, public health managers, scientists, and students. The mature state of the model, and the foreseeable retirement of its lead developer, make this an ideal time to train new operators and transition the system to NANOOS.

The realistic numerical model used here is created using the Regional Ocean Modeling System (ROMS), which integrates the equations of motion and tracer concentration on a rotating, spherical grid. The LiveOcean domain covers all of Oregon, Washington, and Vancouver Island coastal waters, and the Salish Sea – the name for the combined inland waters of Puget Sound, Strait of Georgia, and Strait of Juan de Fuca. The model grid follows lines of constant longitude and latitude, with 500 m spacing in most of the Salish Sea and Washington coastal estuaries, stretching up to 3 km at open boundaries. There are 30 vertical levels, following the bathymetry and free surface. The model is configured to be as realistic as possible, with 45 rivers, 8 tidal constituents, open ocean conditions from a global data-assimilative model (HYCOM), and high-resolution (1.4 km) atmospheric forcing from a regional weather forecast model. The model builds upon prior realistic configurations focused inside of the Salish Sea and on the open coast. The model system includes biogeochemical fields: nitrate, phytoplankton, zooplankton, two sizes of detritus, oxygen, dissolved inorganic carbon, and alkalinity, developed as part of several large, multidisciplinary field programs. Details of the model setup and extensive validation against observations are given in MacCready et al. (2021). Typical root-mean-square errors (RMSE) between model and observations are 31 cm for sea surface height, 0.97 psu for salinity, 0.73 °C for temperature, and 1.09 mg L-1 for dissolved oxygen (DO). We have an archive of over four years of hourly hindcast model output (late 2016 through present). The model is run quasi-operationally, making three-day forecasts every day, the results of which are available to stakeholders through several portals including the LiveOcean Homepage: http://faculty.washington.edu/pmacc/LO/LiveOcean.html, the NANOOS Visualization System, NVS: http://nvs.nanoos.org/Explorer?action=overlay:liveocean_temp.

Brief Synopsis

LiveOcean model enhancement and transition to operations, University of Washington: LiveOcean is a computer model of ocean circulation and biogeochemistry that makes detailed, daily forecasts of currents and water properties including those associated with ocean acidification, hypoxia, harmful algal blooms, and larval transport on fisheries in the Salish Sea and coastal waters of the Northern California Current System. The goal of the proposed work is to test alternative forcing conditions, enhance high-resolution nested sub-models, and transition LiveOcean from its current status as a research tool to an operational asset managed by the NANOOS (UW Applied Physics Lab). Partners: The Northwest Association of Networked Ocean Observing Systems (NANOOS), University of Washington Applied Physics Laboratory, the University of Washington Cooperative Institute for Climate, Ocean, & Ecosystem Studies. Year 1: $299,868.00

References

MacCready, P., McCabe, R. M., Siedlecki, S. A., Lorenz, M., Giddings, S. N., Bos, J., Albertson, S., Banas, N. S., & Garnier, S. (2021). Estuarine Circulation, Mixing, and Residence Times in the Salish Sea. Journal of Geophysical Research: Oceans, 126(2). doi:10.1029/2020jc016738