loading page

Quantifying nitrous oxide emissions in the U.S. Midwest - A top-down study
  • +8
  • Maximilian Eckl,
  • Anke Roiger,
  • Julian Kostinek,
  • Alina Fiehn,
  • Heidi Huntrieser,
  • Christoph Knote,
  • Zachary Barkley,
  • Stephen Ogle,
  • Bianca Baier,
  • Colm Sweeney,
  • Kenneth Davis
Maximilian Eckl
Deutsches Zentrum für Luft- und Raumfahrt (DLR)

Corresponding Author:[email protected]

Author Profile
Anke Roiger
Deutsches Zentrum für Luft- und Raumfahrt (DLR)
Author Profile
Julian Kostinek
German Aerospace Center Oberpfaffenhofen
Author Profile
Alina Fiehn
Deutsches Zentrum für Luft- und Raumfahrt (DLR)
Author Profile
Heidi Huntrieser
German Aerospace Center Oberpfaffenhofen
Author Profile
Christoph Knote
Ludwig-Maximilians-University (LMU)
Author Profile
Zachary Barkley
The Pennsylvania State University
Author Profile
Stephen Ogle
Colorado State University
Author Profile
Bianca Baier
NOAA ESRL Global Monitoring Division
Author Profile
Colm Sweeney
NOAA Global Monitoring Laboratory
Author Profile
Kenneth Davis
The Pennsylvania State University
Author Profile

Abstract

Nitrous oxide (N2O), a potent greenhouse gas and ozone depleting substance, plays a crucial role in the atmosphere. Anthropogenic emissions from agriculture contribute to a rising trend in global N2O emissions and atmospheric concentrations. However, due to insufficient direct observations, regional N2O emissions derived in bottom-up and top-down studies are highly uncertain. The U.S. Midwest is one of the most intensive agriculture areas worldwide and hence may contribute significantly to the observed trend. Recent top-down studies suggest that bottom-up estimates underestimate agricultural emissions in that area by up to an order of magnitude. Here we quantify nitrous oxide emissions in the Midwest in October 2017 and June-July 2019 with a top-down approach. Unique continuous aircraft-based measurements of N2O conducted during the ACT-America campaign together with forward WRF-Chem model simulations are used to scale the EDGAR inventory thus quantifying emissions. On average we had to upscale October 2017 and June-July 2019 agricultural EDGAR 4.3.2/5.0 emissions by a factor of 6.3/3.5 and 11.4/9.9, resulting in 0.42 nmol m-2 s-1 and 1.06 nmol m-2 s-1 emissions in the Midwest, respectively. Finally, calculations of direct soil N2O emissions from the DayCent biogeochemical model are compared to our estimates.