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Develop suite of model applications to assess nutrient loads and predict hypoxia, quantify errors, and guide decision-making in the Gulf. Utilize real-time data assimilation and advanced modeling techniques.
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Goal: Develop a suite of model applications, data products and other tools to - assess and predict the relationships between nutrient loads and hypoxia - quantify sources of error and uncertainty associated with nutrient load reduction targets - forecast the effects of nutrient management actions in the Basin on Gulf hypoxia - provide defensible options to guide restoration and decision-making Gulf Hypoxia Monitoring and ModelingUSEPA Office of Research and Development
June 2003 Hypoxic zone = 4800 km2 Scale = mmol O2/m3/d Gulf Hypoxia Monitoring Surveys Objectives Characterize the spatial and temporal variability in oceanographic state and process variables, including resolution of the seaward and down-plume boundary conditions of the model domain Quantify key processes influencing hypoxia to improve predictive models Develop geo-referenced database to support model development Map shows transect stations and depth contours NRL’s real-time hydrodynamic model (IASONFS) December 2002 March 2003
Parameter Water Sediment Gulf Hypoxia Water Quality and Sediment Sampling
Global Circulation Model Satellite Data (SST/SSE) Wind Models River Flows Naval Research Lab Gulf-Wide Real-Time Data Assimilating Hydrodynamic Model Constituent Mass loadings Water Quality/ Eutrophication Model Sediment Diagenesis Model Mass Balance Modeling Framework Gulf Hypoxia Numerical Modeling Framework
O2 DIC N P 62 differential equations solved simultaneously quite maddening indeed … Coupled WQ & Sediment Model Atmosphere-water interface O2 and CO2 exchange Light Zoop. N&P&TSS All P1 P2 P3 P4 P5 P6 Pyncnocline Organic matter mineralization O2 DIC N P Sediment Diagenesis Eldridge et al., in prep
Sediment Diagenesis Model and Data Needs Attributes of modeled geochemistry • Differential sinking rates • - Cells < fecal pellets and TSS • OM pools for cells and fecal pellets • - Labile and refractory • TSS has organic and mineral components • Variable C:N:P remineralization rates • - Dynamic OM stoichiometry • N pools depict NO3- and NH4+ • - Nitrification • - Denitrification (NO3- electron acceptor) • Reaction rates are temperature dependent Morse and Eldridge, In Press (Marine Chemistry)
Gulf-Wide Real-Time Data Assimilating Hydrodynamic ModelIntra-Americas Sea Ocean Nowcast/Forecast SystemDeveloped and supported by Naval Research Laboratory, Oceanography Division, Ocean Dynamics and Prediction BranchStennis, MS
Prospects/Issues for Long-Term Monitoring of Gulf Hypoxia by USEPA