This project is supported by the NASA Interdisciplinary Science Program The Estuarine Hypoxia Component of the Coastal Ocean Modeling Testbed: Providing Environmental Intelligence to Decision-Makers in the Chesapeake Bay Marjorie Friedrichs, Lyon Lanerolle, Dave Forrest 1, Carl Friedrichs, Raleigh Hood, Malcolm Scully Marjorie Friedrichs 1, Lyon Lanerolle 2, Dave Forrest 1, Carl Friedrichs 1, Raleigh Hood 3, Malcolm Scully 4 1 VIMS, College of William & Mary; 2 Coastal Survey Development Laboratory, NOAA/NOS; 3 Center for Environmental Science, University of Maryland; 4 Woods Hole Oceanographic Institution BACKGROUND The Chesapeake Bay and its associated tidal tributaries, which together form one of the world’s largest estuaries, is host to an extensive suite of commercial and recreational industries that have an estimated value of more than one trillion dollars. In addition the Chesapeake watershed is home to more than 17 million people. Unfortunately, however, this is one of many coastal systems where degraded water quality and hypoxia are a major concern. In recent decades the Chesapeake Bay has suffered from increased nutrient loading due to population growth and changing land use. Increases in nutrient loads have caused significant eutrophication, which in turn has led to a substantial increase in hypoxic events, causing detrimental effects on macrobenthic production, benthic community diversity and the demersal fish community. Partially as a result of the number of public livelihoods affected by hypoxic events, the Chesapeake Bay is highlighted as a region of specific interest in terms of developing a NOAA operational system that can provide decision makers with actionable information to make informed choices for environmental protection and economic decisions. Fully understanding and being able to hindcast and forecast hypoxic events is thus a critical aspect of environmental intelligence in the Chesapeake Bay region.. SCENARIO-BASED OPERATIONAL FORECASTING In cooperation with the US Environmental Protection Agency, evaluate regulatory nutrient reduction scenarios in parallel with the regulatory model. Utilize the suite of projected water quality simulations to define the uncertainty in regulatory estimates of estuarine response to reduced nutrient loads In cooperation with the US Environmental Protection Agency, evaluate regulatory nutrient reduction scenarios in parallel with the regulatory model. Utilize the suite of projected water quality simulations to define the uncertainty in regulatory estimates of estuarine response to reduced nutrient loads CHESAPEAKE BAY ENVIRONMENTAL PREDICTION SYSTEM Through a University of Maryland Center for Environmental Science & Virginia Institute of Marine Science (VIMS) collaborative effort, nowcasts and forecasts of Chesapeake Bay oxygen levels are currently being served on the VIMS website: r-with-content-page/ Through a University of Maryland Center for Environmental Science & Virginia Institute of Marine Science (VIMS) collaborative effort, nowcasts and forecasts of Chesapeake Bay oxygen levels are currently being served on the VIMS website: r-with-content-page/ Fig. 2: XXXX NOAA CHESAPEAKE BAY OPERATIONAL FORECAST SYSTEM (CBOFS) We are currently incorporating the most reliable model formulations into a pre-operational physical code at NOAA CSDL, thus positioning NOAA so that it can consider adopting this new model with minimal effort during its next upgrade. This will provide a seamless scheduled transition that will establish a fully operational oxygen nowcast/forecast capability within NOAA for the Chesapeake Bay, thus addressing one of the High Priority Focus areas identified in the NOAA Ecological Forecasting Roadmap. OBJECTIVES To assess the readiness and maturity of a suite of existing coastal ecological community models for determining past, present and future hypoxia events within the Chesapeake Bay To improve environmental intelligence in the Chesapeake Bay by accelerating the transition of hypoxia model formulations from academic research to federal operational facilities (NOAA and EPA) Achieving these overall objectives is feasible because of the multiple existing hydrodynamic models and dissolved oxygen models currently being successfully implemented in the Chesapeake Bay region. (See multiple model comparisons described in Irby et al. poster.) Fig. 1: Horizontal grid structure for multiple models in the Chesapeake Bay. ROMS models employ curvilinear grids over land and water. ROMS-RCA utilize 80x120 cells. ChesROMS utilize 100x150 cells, CH3D-ICM has 11,000 wetted rectanualar horizontal surface cells. Increasing spatial resolution ROMS-RCAChesROMS CH3D-ICM We are working to add dissolved oxygen to the set of fields currently available (including T and S as shown above) in the existing CBOFS: We are working to add dissolved oxygen to the set of fields currently available (including T and S as shown above) in the existing CBOFS: This work was funded by the NOAA NOS Integrated Ocean Observing System (IOOS) as part of the Coastal Modeling Testbed (NA13NOS ). Observations and Forcings Regulatory Model COMT Models Ensemble of Implementations Calibration Regulatory Projected Water Quality COMT Models Ensemble Projected Water Quality Nutrient Reduction Scenario Estimate Uncertainty in Projections As part of the COMT, simulations will be conducted using multiple models forced by the official reduction strategies being examined by the NOAA/EPA Chesapeake Bay Program, in their assessment of whether Total Maximum Daily Load implementation will result in improved DO concentrations throughout the Bay. We will compare the predicted responses of nutrient reduction strategies generated from the COMT models to those obtained from the operational/regulatory NOAA/EPA model. The resulting DO concentrations from the multiple models will be compared to assess uncertainty in future water quality improvement under nutrient load reductions. This work is being conducted in close collaboration with our NOAA/EPA colleagues who are responsible for running the operational model scenarios. Our results will be of significant management interest, as they will help establish uncertainty bounds on the official nutrient reduction requirements.