Work Description

Readme for: "Posterior Flux Ensemble for Measurement of Agriculture Illuminating farm-Zone Emissions of N2O (MAIZE)"

Authors: Dr. E.A. Kort (https://orcid.org/0000-0003-4940-7541), Dr. Genevieve Plant (https://orcid.org/0000-0003-1973-8243).

For questions or information, contact the PI E.A. Kort at eakort@umich.edu or G. Plant at geplant@umich.edu

Description: Ensemble of optimized posterior N2O (nitrous oxide) fluxes derived from a Bayesian Inversion framework and in-situ aircraft observations of Iowa in 2021 (May 26, 2021 – June 4, 2021) and 2022 (May 18, 2022 – May 31, 2022) from “Airborne measurements reveal high spatiotemporal variation and the heavy-tail characteristic of nitrous oxide emissions in Iowa,” citation below. For each flight day there (12 in total), there are three separate files that represent fluxes derived for three distinct spatial resolutions. Further details about the ensemble members are provided in Dacic, Plant, & Kort (2024).

Citation: Dacic N, Plant G, Kort EA, “Airborne measurements reveal high spatiotemporal variation and the heavy-tail characteristic of nitrous oxide emissions in Iowa,” in revisions for JGR: Atmospheres.

Methodology: In-situ atmospheric measurements of N2O were made by a Mooney aircraft in 2021, 2022 in the agriculture regions of Iowa. In 2021, measurements of nitrous oxide (N2O) were made using an Aerodyne Research, Inc. TILDAS Compact Single Laser N2O Analyzer. In 2022, measurements of N2O were made using an LGR N2O/CO analyzer (Model 916-0015, Los Gatos Research (LGR), ABB). Frequent calibrations of both were made in-flight using the FCHAOS method detailed in Gvakharia et al (2018), and the instruments were calibrated to the WMO-N2O_X2006A and WMO-CO_X2014A scales prior to use in the field. A Bayesian inversion framework was employed to generate surface N2O fluxes consistent with our atmospheric sampling. An ensemble approach was used to account for sensitivities to the a priori flux estimates and methodological choices. Further details are provided in “Airborne measurements reveal high spatiotemporal variation and the heavy-tail characteristic of nitrous oxide emissions in Iowa,” citation below.

Citation: Dacic N, Plant G, Kort EA, “Airborne measurements reveal high spatiotemporal variation and the heavy-tail characteristic of nitrous oxide emissions in Iowa,” in revisions for JGR: Atmospheres.

Instrument calibration details: Gvakharia A, Kort EA, Smith M, Conley S, Testing and evaluation of a new airborne system for continuous N2O, CO2, CO, and H2O measurements: the Frequent Calibration High-performance Airborne Observation System (FCHAOS), Atmos. Meas. Tech. 11, 6059-6074, https://doi.org/10.5194/amt-11-6059-2018, 2018.

Ensemble Members:
1. edgar x1: EDGAR v7 N2O annual fluxes, regridded using nearest-neighbor approach.
2. edgar xPostMean: EDGAR v7 N2O annual fluxes, regridded using nearest-neighbor approach, scaled to mean daily posterior flux (see Section S4 of accompanying paper).
3. upsampled x1: Field-specific DayCent-CR version 1.0.2 model runs, upsampled to full domain by crop type (see Section 2.3 of accompanying paper).
4. upsampled x1 bkg0-sd(upwind): Upsampled model, background defined as the minimum of upwind concentration minus the standard deviation of upwind transect.
5. upsampled x1 bkg0+sd(upwind): Upsampled model, background defined as the minimum of upwind concentration plus the standard deviation of upwind transect.
6. upsampled xPostMean bkg=0th: Upsampled model, magnitude scaled by posterior mean of unscaled prior result, background defined as the minimum of upwind concentration.
7. upsampled xPostMean bkg=5th: Upsampled model, magnitude scaled by posterior mean of unscaled prior result, background defined as the 5th percentile of upwind concentration.
8. upsampled xPostMean – edgarNonAg: Upsampled model, magnitude scaled by posterior mean of unscaled prior result, enhancements from non-agricultural soil sources in EDGAR v7 2021 are modeled and then subtracted from observed enhancement signal.
9. upsampled xPostMean - edgarNonAgx10: Upsampled model, magnitude scaled by posterior mean of unscaled prior result, enhancements from 10x non-agricultural soil sources in EDGAR v7 2021 are modeled and then subtracted from observed enhancement signal.
10. upsampled xPostMean sQ=0.01: Upsampled model, magnitude scaled by posterior mean of unscaled prior result, diagonal element in Q set to 0.01 μmol/m2/s.
11. Lu_total: Model results from Lu et al. (2022, DOI: 10.1111/gcb.16061), regridded using a nearest-neighbor approach.
12. upsampled xPostMean res=0.01: Upsampled model, magnitude scaled by posterior mean of unscaled prior result, at 0.01° spatial resolution.
13. upsampled xPostMean res = 0.03: Upsampled model, magnitude scaled by posterior mean of unscaled prior result, at 0.03° spatial resolution.

File Notes:
a) Separate folders for each flight day each contain three netcdf files (.nc), named for the spatial resolution of the N2O fluxes. For example, the posterior fluxes for May 31, 2021 are provided in “MAIZE_20210531_02deg.nc” for ensemble members at 0.02 degree resolution (ensemble members 1-11 above), “MAIZE_20210531_01deg.nc” and “MAIZE_20210531_03deg.nc” for ensemble members at 0.01 deg (ensemble number 12) and 0.03 deg (ensemble number 13), respectively.
b) Flux units are micro-mol N2O /m2/s
c) Posterior fluxes are provided for pixels for which the aircraft measurements are sensitive, within a 90% contour (see Figure S5, S6 in the accompanying paper).

Airborne N2O measurements used in this work are available here:
Kort, E. A., Plant, G., Dacic, N. (2022). Aircraft Data (2021) for Measurement of Agriculture Illuminating farm-Zone Emissions of N2O (MAIZE) [Data set], University of Michigan - Deep Blue Data. https://doi.org/10.7302/0jvh-0c91
Kort, E. A., Plant, G., Dacic, N. (2024). Aircraft Data (2022) for Measurement of Agriculture Illuminating farm-Zone Emissions of N2O (MAIZE) [Data set], University of Michigan - Deep Blue Data. https://doi.org/10.7302/tmfd-nw87

Citation for this dataset: Kort, E. A., Plant, G., Dacic, N. Posterior Flux Ensemble for Measurement of Agriculture Illuminating farm-Zone Emissions of N2O (MAIZE) [Data set], University of Michigan - Deep Blue Data. https://doi.org/10.7302/9w5m-mn30