CMAQv5.0.2 NH3 bidirectional exchange

Brief Description

The NH3_dep diagnostic output using the NH₃ Bidirectional Exchange option was fixed to include deposition to water. The apoplast compensation point was parameterized following Massad et al. 2010. Model algorithms were updated to support the fertilizer composition and application information now available in new EPIC output.

Significance and Impact

Generally the Massad et al. (2010) apoplast compensation point was parameterization is higher than the previous lookup table. This slightly increases the emissions and transport of NH₃ and formation of NO₃ aerosols during the growing season, spring through fall. The fertilizer composition information generally decreases emissions and better represents management practices.

Affected files

ABFLUX_MOD.F

References

• Massad, R.-S., Nemitz, E., and Sutton, M. A.: Review and parameterisation of bi-directional ammonia exchange between vegetation and the atmosphere, Atmos. Chem. Phys., 10, 10359-10386, doi:10.5194/acp-10-10359-2010, 2010.
• Bash, J.O., Cooter, E.J., Dennis, R.W., Walker, J.T., Pleim. J.E., Evaluation of a regional air-quality model with bi-directional NH3 exchange coupled to an agro-ecosystem model, Biogeosciences, 10, 1635-1645, 2013.
• Cooter, E.J., Bash, J.O., Benson V., Ran, L.-M., Linking agricultural management and air-quality models for regional to national-scale nitrogen deposition assessments, Biogeosciences, 9, 4023-4035, 2012.

Contact

Jesse Bash, Atmospheric Modeling and Analysis Division, U.S. EPA