B115-0007
A multi-year constraint on ammonia emissions and deposition within the U.S. Corn Belt

Wednesday, 16 December 2020
Poster
John Baker, USDA-ARS, St. Paul, MN, United States, Cheng Hu, Nanjing University of Information Science and Technology, Yale-NUIST Center on Atmospheric Environment, Nanjing, China, Timothy J Griffis, Univ Minnesota, Saint Paul, MN, United States, Alexander Lee Frie, University of California Riverside, Environmental Sciences, Riverside, CA, United States; University of Minnesota Twin Cities, Soil, Water, and Climate, Minneapolis, MN, United States, Dylan B Millet, University of Minnesota Twin Cities, St Paul, MN, United States and Zhongjie Yu, Rutgers University, Harrison, NJ, United States
Abstract:
The U.S. Corn Belt is a globally relevant agricultural source of atmospheric ammonia (NH3). NH3 emissions from this region, their deposition, and the interannual variability of these quantities are still poorly understood. Here, we combine hourly tall tower (100 m) and bi-weekly, spatially distributed, ground NH3 observations, National Emission Inventories, and WRF-Chem modeling to constrain NH3 emissions in the Corn Belt over the period of April through September, 2017 to 2019. The results revealed: (1) large biases exist in the a priori monthly NH3 emissions, especially for May, June, and August, (2) that posteriori NH3 emissions peaked from May to July, with emission rates varying from 4.17 to 4.47 nmol m-2 s-1 for three years averages; (2) growing season averaged NH3 mixing ratios for agriculture regions were 6.74±1.40 ppb, 7.06±1.40 ppb, 6.63±1.47 ppb, and the dry deposition were 1.40 ± 0.03 nmol m-2 s-1, 1.48 ± 0.03 nmol m-2 s-1, and 1.39 ± 0.03 nmol m-2 s-1 for 2017, 2018 and 2019, respectively; (3) No significant interannual variations were found for NH3 emissions, mixing ratio, and dry depositions, when up scaling the total nitrogen deposition from April through September, the estimation was 2.87 kg N/ha per growing season.
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