A Multiyear Constraint on Ammonia Emissions and Deposition Within the US Corn Belt

Cheng Hu, Timothy J Griffis, Alexander Frie, John M. Baker, Jeffrey D Wood, Dylan B. Millet, Zhongjie Yu, Xueying Yu, Alan C. Czarnetzki

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


The US Corn Belt is a global hotspot of atmospheric ammonia (NH3), a gas known to adversely impact the environment and human health. We combine hourly tall tower (100 m) measurements and bi-weekly, spatially distributed, ground-based observations from the Ammonia Monitoring Network with the US National Emissions Inventory (NEI) and WRF-Chem simulations to constrain NH3 emissions from April to September 2017–2019. We show that: (1) NH3 emissions peaked from May to July and were 1.6–1.7 times the annual NEI average; (2) average growing season NH3 emissions from agricultural lands were remarkably similar across years (3.27–3.64 nmol m−2 s−1), yet showed substantial episodic variability driven by meteorology and land management; (3) dry deposition was 40% of gross emissions from agricultural lands and exceeded 100% of gross emissions in natural lands. Our findings provide an important benchmark for evaluating future NH3 emissions and mitigation efforts.

Original languageEnglish (US)
Article numbere2020GL090865
JournalGeophysical Research Letters
Issue number6
StatePublished - Mar 22 2021

Bibliographical note

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  • US Corn Belt
  • WRF-Chem modeling
  • agriculture
  • ammonia emissions
  • deposition
  • forests
  • mitigation
  • reactive nitrogen
  • tall tower


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