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Updates on Soil NOx parameterization in CMAQ v5.1
Citation:
Rasool, Q., J. Bash, R. Zhang, E. Cooter, B. Lash, D. Cohan, AND L. Lamsal. Updates on Soil NOx parameterization in CMAQ v5.1. 2016 CMAS Conference, Chapel Hill, NC, October 24 - 26, 2016.
Impact/Purpose:
The National Exposure Research Laboratory (NERL) Computational Exposure Division (CED) develops and evaluates data, decision-support tools, and models to be applied to media-specific or receptor-specific problem areas. CED uses modeling-based approaches to characterize exposures, evaluate fate and transport, and support environmental diagnostics/forensics with input from multiple data sources. It also develops media- and receptor-specific models, process models, and decision support tools for use both within and outside of EPA.
Description:
NOx has been well established to impact the formation of ozone and particulate matter. Soil NO emissions comprise approximately 20% of the global NOx budget and are a leading source of NOx in rural and remote areas. NO is emitted from soil as a result of complex biogeochemical interactions of soil N with specific microbial niches. Accurate estimation of soil NO could enhance simulations of ozone, particulate matter, and atmospheric deposition flux in regional air quality models like CMAQ. Uncertainty in the temporal and spatial distribution of soil NO emissions arises from a lack of dynamic representation of soil properties, land use classification and mineral nitrogen availability in the soil. This study presents an update to the Berkley Dalhousie Soil NOx parametrization (BDSNP) scheme in CMAQ v5.1 to enhance its consistency with CMAQ-EPIC representation of the nitrogen cycle and bidirectional ammonia exchange. This updated parametrization constrains soil NO emissions by incorporating detailed agricultural fertilizer inputs from EPIC and CMAQ modeled N deposition into the soil N pool. We implement fractional land use definitions rather than dominant land use classification for more accurate sub-grid cell soil NO estimates. This updated scheme is currently implemented for the continental US and could be extended to a global scale. Model results are evaluated against observed aerosol and ozone concentrations, satellite observations of NO2, and deposition fluxes. The impact on total dry and wet nitrogen deposition will be discussed.
