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LiveOcean: a daily forecast model of Ocean Acidification for Washington coastal waters

LiveOcean is a computer model simulating ocean water properties in the NE Pacific and Salish Sea. The model provides 3-day forecasts of Aragonite saturation state and pH of waters entering shellfish growing areas on the coast. The project is funded by Washington state through the Washington Ocean Acidification Center (WOAC). The model system is built using existing 3D circulation-biogeochemistry hindcast models, incorporating carbon chemistry.

The circulation model is currently creating 3-day forecasts of currents. Maps of all biogeochemical fields at a number of depths may be viewed and compared to observations in the NANOOS NVS.

LiveOcean is an ongoing project of the UW Coastal Modeling Group: Dr. Parker MacCready (UW Oceanography, lead), Dr. Samantha Siedlecki (U. Connecticut, oxygen & carbon chemistry), Dr. Ryan McCabe (UW JISAO, validation), and Dr. Neil Banas (University of Strathclyde, Scotland, ecosystem modeling).

Disclaimer: The coastal ocean forecasts made by LiveOcean are an experimental product intended for research use only. In no event will UW or any of its employees be liable for any direct, indirect, incidental, consequential, special or exemplary damages or lost profit resulting from any use or misuse of these research model forecasts.

Figure 1. Tidally-averaged Surface salinity (left), temperature and currents (right) from the LiveOcean hindcast of 2014. The full model domain is shown, which includes the Washington coast, and parts of the Oregon and Vancouver Island coasts. The Salish Sea is included, although it is not well-resolved with the current 1.5 km horizontal grid.

Model Configuration

Forcing


Validation

Testing model performance against observations is essential to knowing how to use the forecasts. We put about half of our effort into validation, gathering observations from many regional scientific and monitoring efforts. Examples are shown in Figures 2 and 3 bleos. The model system is built using a framework developed to forecast Harmful Algal Blooms (PNWTOX, Dr. Barbara Hickey, PI). Extensive model physical validation is documented in Giddings et al. (2014). The ecosystem model and its validation are given in Davis et al. (2014). Siedlecki et al. (2015) present the detritus and oxygen model and its validation.


Figure 2. Comparison of model temperature and salinity to mooring records collected by the Olympic Coast National Marine Sanctuary (OCNMS). The mooring is in 27 m of water off the central Washington shelf (map, upper right). The model was run continuously starting in January 2013, and observations (black lines in left panels) were collected during the summer and early fall months. At this location the model (gray lines) shows good skill at reproducing both the mean and the variability of the temperature and salinity. The fields shown are "subtidal" meaning they have been filtered to remove tidal oscillations.

These comparisons look excellent, however they are just for a single location and only for temperature and salinity, which have well-understood physics. In general model skill decreases as you move farther offshore.


Figure 3. These panels show the variation with depth of biogechemical properties at three offshore locations in 2015 (one station per row). They are compared with bottle data from a NOAA Ocean Acidificaion cruise. We simulate Nitrate, Dissolved Oxygen, Total Alkalinity (TA) and Total Inorganic Carbon (TIC), along with phytoplankton and zooplankton. TIC and TA are then used calculate pH and Aragonit Saturation State. The model simulation of these variable is quite good.


Next Steps

REFERENCES