Estimating Atmospheric NH3 Exchange in the Midwestern U.S. using SURFATM-NH3

Tuesday, 16 December 2014
Daryl Sibble1, Jason Anthony Caldwell1, Thomas Caillaud2, Elijah Johnson1, Erwan Personne2, Rick D Saylor3, Mark Heuer4, Andrew Joseph Nelson5, Mark J Rood6, Sotiria Koloutsou-Vakakis7 and LaToya Myles8, (1)Florida Agricultural and Mechanical University, Tallahassee, FL, United States, (2)AgroParisTech, Paris, France, (3)NOAA Air Resources Laboratory, Oak Ridge, TN, United States, (4)NOAA/ATDD, Oak Ridge, TN, United States, (5)University of Illinois at Urbana Champaign, Urbana, IL, United States, (6)University of Illinois, Urbana, IL, United States, (7)Univ of IL--Civil & Envir Engr, Urbana, IL, United States, (8)NOAA Oak Ridge, Oak Ridge, TN, United States
The bi-directionality of ammonia (NH3) exchange in canopies is influenced by changes in the atmosphere, vegetation, and soils. Accurate simulation of exchange processes is challenging due to uncertainties in stomatal compensation point, soil resistances, and other key inputs. As part of a study to quantify NH3 emissions from fertilized maize in the Midwestern U.S., the SURFATM-NH3 model was used to simulate NH3 flux using measurement data (chemical flux, micrometeorology, and soil) collected over an entire growing season from May-September 2014. Initial simulations reveal that NH3 flux predictions display a statistically significant correlation with atmospheric variables that influence the transfer of moisture and energy (i.e. temperature, relative humidity, radiation). A function that describes the relationship between the emission potentials, meteorological data, and the vegetative canopy flux is also observed, which could be utilized by future studies to increase the accuracy of forecasting the source/sink behavior of the NHcanopy flux.