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Marine Sciences Division

Earth Systems Modeling

Nearshore Carbon Fluxes

Change in coastal environments represents a combination of natural evolution and human induced impacts. Tidal wetlands are important as they are hot-spots of biogeochemical exchanges and transformations. Understanding carbon (C) fluxes and processes at the wetland-ocean interface has increasing significance in light of accelerated climate change, particularly since managed restoration of wetlands is considered one of the most promising climate change mitigation activities. Increasing coastal urbanization is also expected to result in both degradation and loss of tidal marshes, as well as changes in inundation dynamics and salinity regimes.

To better understand how climate change and urbanization impacts tidal marshes, MSL scientists and university partners are studying carbon fluxes and exchanges (dissolved, particulate, and gaseous CO2, methane [CH4], and nitrous oxide [N2O] components) at the tidal wetland-estuarine-atmosphere interface. A key tool in this work is a three dimensional ocean circulation model that is combined with an Integrated Compartment Model for water quality to simulate the physical and biological characteristics of coastal areas. The research marsh located at MSL is also a key resource where effluxes to the air and water are measured for model parameterization.

An ongoing project studying Chesapeake Bay is using these models in combination with advanced remote sensing observations to assess the role of tidal wetland carbon fluxes across a range of spatial scales (from individual marshes and sub-estuaries to the whole estuarine system), and across a range of time scales (tidal, seasonal, inter-annual). The influence of natural and anthropogenic pressures on these processes is being assessed through model simulations under various environmental change scenarios (i.e., extreme flooding, sea level rise, increased CO2, nutrient enrichment). Concurrent measurements of biogeochemical parameters and long-term observations are being used to inform the modeling effort. A novel feature of the modeling is inclusion of a module to simulate the drag imposed by marsh grasses that provides a realistic representation of intertidal marsh hydrodynamics. Model output and observed data are compared for hydrodynamic model validation and small-scale circulation features are examined.

Extreme Event Prediction and Management

Extreme Event Prediction and Management

Coastal zones comprise only 17% of land area in the United States, but are home to more than half of the population and a wealth of natural and economic resources, including some of the most important energy and transportation infrastructures, ports and harbor systems, and prestigious ecosystems. However, coastal zones are vulnerable to the risks of anthropogenic and natural disturbances, such as sea level rise, river flooding, and storm surge induced by tropical and extra-tropical cyclones.

Researchers at MSL are developing a suite of high-resolution coastal storm surge models to simulate the multi-facets, multi-scales processes in the coastal zones and to investigate the interplay and feedback between coastal processes and human activities using an integrated earth systems modeling approach.

An ongoing project that is funded from the U.S. Department of Energy's Office of Biological and Environmental Research is developing an advanced coastal storm surge model. This model permits simulation of the inundation caused by storm surge and relative sea level rise and evaluate the impacts on the northern Gulf coastal energy infrastructures. The storm surges induced by four historical hurricanes (Rita, Katrina, Ivan, and Dolly) were simulated and compared to observed water levels at National Oceanic and Atmospheric Administration tide stations. Model results suggested that hurricane-induced storm surge height and coastal inundation could be exacerbated by future global sea level rise and subsidence, and that responses of storm surge and coastal inundation to the effects of sea level rise and subsidence are highly nonlinear and vary on temporal and spatial scales.

Human — Natural Systems Modeling

Human — Natural Systems Modeling

Predicting the future impacts of human activities and climate change on coastal environments is critical for resource managers tasked with managing air, land, and water resources. An essential tool in this process is computational models that provide regional-scale representations of the coastal environment including ocean and land hydrology and land/ocean biogeochemistry.

Researchers at MSL are working to develop integrated models of human and climate impacts in the terrestrial-estuarine system. A current project called "Snow Caps to White Caps" seeks to provide data and insight for water resource managers to support future management actions that address changes in the availability of both fresh and marine water resources in the Puget Sound basin.

This effort consists of a team of scientists and engineers from Pacific Northwest National Laboratory (PNNL) and the University of Washington (UW) to examine the movement of water in the Snohomish basin, under conditions of future changes in climate and land use/land cover using a set of linked numerical models. In consultation with water resource managers, the research team developed a set of research and management questions to be tested with the output of an integrated model system that follows water from the top of the mountains through the watershed, across the floodplain, into the river slough, and into Puget Sound via Port Gardner Bay and Possession Sound. The use of an integrated modeling framework allowed the team to carry out model linkages, quality control, display, and archiving of the results in an organized manner.

The results of the study are being presented to interested parties at the state and local level, and extrapolation of the potential for applying the Snow Caps to White Caps methods beyond the Snohomish to other Puget Sound basins is under way.

Marine Sciences Laboratory

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