Ocean acidification model development moves into second validation phase

West Coast researchers working to develop a computer model that predicts how the region’s coastal waters will be affected by ocean acidification and hypoxia have advanced to a second phase of validation to increase confidence in the model’s outputs.

The focus of this validation phase is to confirm that the West Coast ocean acidification model is accurately reflecting the biogeochemical cycling patterns of nutrients that enter West Coast waters from a variety of land-based and air-based sources, including wastewater outfalls and atmospheric deposition. This validation step will pave the way for coastal resource managers to have confidence in the model’s ability to answer regional management questions.

Researchers are comparing the model’s predicted outputs to field data collected by SCCWRP member agencies and other partners, including a series of biogeochemical process rates studies focusing on the fate of nutrients from wastewater effluent in the Southern California Bight.

The modeling project is a five-year initiative to help West Coast managers understand which coastal marine habitats are most vulnerable to ocean acidification and to what extent local, land-based sources of nutrients are exacerbating acidification conditions. The modeling work involves coupling West Coast physical and biogeochemical ocean models to understand the relative contributions of local and global carbon dioxide emissions, natural upwelling processes, and nutrients introduced via wastewater effluent, stormwater runoff and atmospheric deposition.

During the model’s first validation phase, completed in 2016, researchers focused on confirming that the model is accurately capturing large-scale, dynamic oceanic forcing at the scale of the Pacific Ocean basin, including coastal upwelling events that pull deeper waters to the ocean’s surface.

The second validation phase is expected to be completed in summer 2018, at which time researchers will use the model to begin answering management questions about West Coast ocean acidification and hypoxia patterns.