Forecasting ocean acidification in the coastal waters of the Pacific Northwest

Chair: James Orr

Siedlecki, S.A. (1)*, Hermann, A (1), Nguyen, T.T. (1), Bond, N. (1), Kaplan, I.C. (2), Alin, S. (3), Feely, R.A. (3), Bednarsek, N. (4), Newton, J. (5)

1 Joint Institute for the Study of the Atmosphere and Ocean, University of Washington, Box 355672, 3737 Brooklyn Ave NE, Seattle WA 98195 USA
2 Conservation Biology Division, Northwest Fisheries Science Center, National Marine Fisheries Service, NOAA, 2725 Montlake Blvd E, Seattle WA 98112 USA
3 NOAA, Pacific Marine Environmental Laboratory, 7600 Sand Point Way NE, Seattle WA 98115 USA
4 School of Marine and Environmental Affairs, University of Washington, 3707 Brooklyn Ave NE, Seattle WA 98195 USA
5
Applied Physics Laboratory, University of Washington, 1013 NE 40th St, Box 355640, Seattle, WA 98105 USA

Background
Resource managers at the state, federal, and tribal levels make decisions on a weekly to quarterly basis, and fishers operate on a similar timeframe. Since biological components respond strongly to climate and physical forcing, for instance in the Northern California Current ecosystem off the US West Coast, prognostic information could yield substantial benefits for both managers and stakeholders.

Methods
To determine the potential of a support tool for these efforts, a seasonal forecast system has been developed. JISAO’s Seasonal Coastal Ocean Prediction of the Ecosystem (J-SCOPE), features dynamical downscaling of regional ocean conditions in Washington and Oregon waters using a combination of a high-resolution model and forecasts from NOAA’s Climate Forecast System (CFS). J-SCOPE has been extended to include carbonate chemistry. A model hindcast for 2013 is compared to local observations of aragonite saturation. Forecasts for 2016 will be discussed.

Findings
The model reproduces and forecasts the seasonal change in corrosive water observed in the region. The volume of undersaturated water increases over the upwelling season, occupying more of the water column later in the upwelling season. This results in increasingly stressful conditions over most of the water column for biota on the shelf as the upwelling season progresses. New forecasted indices based on ocean acidification metrics specific to the shellfish and crab habitats will be showcased and the preliminary skill of these indices discussed.

Conclusions
Results indicate J-SCOPE forecasts have skill on timescales of two to four months for temperature and oxygen. Experiments suggest that seasonal forecasting of ocean conditions important for fisheries are possible with the right combination of ingredients.