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Future Directions and the Importance of Scale in Estimating Atmospheric Nitrogen Loading to the next generation Chesapeake Bay model
Citation:
Bash, J., D. Schwede, AND C. Hogrefe. Future Directions and the Importance of Scale in Estimating Atmospheric Nitrogen Loading to the next generation Chesapeake Bay model. Chesapeake Community Research Symposium 2020, Parole, Maryland, June 08 - 10, 2020.
Impact/Purpose:
The scale of atmospheric pollutant emissions, transport and deposition in atmospheric chemical transport models is typically on the order of 10 to 1000s of kilometers squared due to the bulk physical processes being considered, while the scale of distributed watershed models and best management practices used to mitigate nutrient runoff are on the order of 10 to 1000s of meters squared. Chemical transport models can be run using explicit physics at a finer scale. However, this becomes computationally prohibitive on the larger watershed scale. In order to provide relevant inputs to the next generation of watershed/water quality models, the U.S. EPA's Community Multiscale Air Quality (CMAQ) model has a new land use specific deposition option. Here we will demonstrate the mapping of land use specific deposition to the native resolution of water quality models used by the Chesapeake Bay program with an emphasis on conserving the mass of nitrogen deposited across multiple scales.
Description:
Atmospheric deposition is one of the largest loadings of nitrogen to the Chesapeake Bay Watershed. The scale of atmospheric pollutant emissions, transport and deposition in atmospheric chemical transport models is typically on the order of 10 to 1000s of kilometers squared due to the bulk physical processes being considered, while the scale of distributed watershed models and best management practices used to mitigate nutrient runoff are on the order of 10 to 1000s of meters squared. Chemical transport models can be run using explicit physics at a finer scale. However, this becomes computationally prohibitive on the larger watershed scale. In order to provide relevant inputs to the next generation of watershed/water quality models, the U.S. EPA's Community Multiscale Air Quality (CMAQ) model has a new land use specific deposition option. Results and an evaluation from an annual simulation of this model will be presented. Additionally, the land use specific dry deposition results will be mapped to higher resolution versions of the CMAQ land use data, 30-meter NLCD data, to parameterize finer scale atmospheric deposition rates for inputs in the next generation of high-resolution water quality models. The mass of the total deposited nitrogen output from CMAQ and the higher resolution post processed product and its potential use in best management practice scenarios will be discussed.
