The Atmospheric Chemistry and Canopy Exchange Simulation System for Ammonia (ACCESS-NH3): Formulation and Application to a Corn Canopy

Rick Saylor1, LaToya Myles2, Nebila Lichiheb3, Mark Heuer4, Andrew Nelson5, Sotiria Koloutsou-Vakakis6 and Mark Rood7

As nitrogen oxide and sulfur dioxide emissions decrease in the U. S. as a result of implemented air quality regulations, agricultural emissions of ammonia (NH3) are being recognized as playing an increasingly important role in fine particle (PM2.5) formation.  If regulations on agricultural emissions are implemented in the future, it will be necessary to have reliable models of NH3 bi-directional exchange over a variety of crop types to help formulate effective control or mitigation strategies. The Atmospheric Chemistry and Canopy Exchange Simulation System for Ammonia (ACCESS-NH3) is a multilayer, single column model that simulates the bi-directional transport and exchange of ammonia throughout the soil-plant-atmosphere continuum.  In this presentation, the ACCESS-NH3 modeling system is described and results from its application to a corn (Zea mays) canopy are presented.  NH3 concentration and flux measurements, along with micrometeorological and environmental observations, were made within and above a Zea mays canopy at the University of Illinois Energy Biosciences Institute Energy Farm in Urbana, IL, during the entire growing season of 2014.  ACCESS-NH3 has been applied to the data obtained during this field experiment to evaluate the model and to assess how NH3 interacts with the Zea mays canopy and how these interactions vary over the growing season and as a function of environmental conditions. Results from the evaluations and simulations will be presented.


5University of Illinois at Urbana-Champaign,
6University of Illinois at Urbana-Champaign,
7University of Illinois at Urbana-Champaign,