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Updates to Fertilizer and Biogenic NH3 emissions for the National Emissions Inventory
Citation:
Bash, J., JohnT Walker, V. Rao, Z. Wu, C. Baublitz, AND I. Rumsey. Updates to Fertilizer and Biogenic NH3 emissions for the National Emissions Inventory. 2023 International Emissions Inventory Conference, Seattle, WA, September 26 - 29, 2023.
Impact/Purpose:
Recent measurements of ammonia fluxes indicate that the non-agricultural biogenic cycling of NH3 was underestimated in CMAQ v5.3. This is further supported by measurements of ammonium in soil and living vegetation samples taken at the National Atmospheric Deposition Program’s Ammonia Monitoring Network (AMoN) sites and available from the global TRY Plant Trait Database. Here we present updates to CMAQ v5.4 used to address this discrepancy between the CMAQ model and observations and the impact that this has on estimating NH3 emissions from agricultural and biogenic sources for the U.S. Annual simulations of CMAQ v5.3.2 and CMAQv5.4 completed for 2020 coupled to the USDA’s Environmental Policy Integrated Climate model (EPIC) model were used to estimate fertilizer and biogenic NH3 emissions for use in the 2020 National Emissions Inventory. The update to plant functional type emission potentials in CMAQ v5.4 resulted in a reduction in the modeled bias when compared to AMoN ambient NH3 observations. This bias reduction was largest in the summer when biogenic NH3 emissions are largest. The annual contribution of the biogenic NH3 emissions was approximately 6% of the annual 2020 NH3 emissions. Estimated emission increases in the 2020 NEI for this sector compared to the 2017 NEI, model sensitivities to land use data, and future measurement and model needs will be discussed.
Description:
Recent measurements of ammonia fluxes indicate that the non-agricultural biogenic cycling of NH3 was underestimated in CMAQ v5.3. This is further supported by measurements of ammonium in soil and living vegetation samples taken at the National Atmospheric Deposition Program’s Ammonia Monitoring Network (AMoN) sites and available from the global TRY Plant Trait Database. Here we present updates to CMAQ v5.4 used to address this discrepancy between the CMAQ model and observations and the impact that this has on estimating NH3 emissions from agricultural and biogenic sources for the U.S. Annual simulations of CMAQ v5.3.2 and CMAQv5.4 completed for 2020 coupled to the USDA’s Environmental Policy Integrated Climate model (EPIC) model were used to estimate fertilizer and biogenic NH3 emissions for use in the 2020 National Emissions Inventory. The update to plant functional type emission potentials in CMAQ v5.4 resulted in a reduction in the modeled bias when compared to AMoN ambient NH3 observations. This bias reduction was largest in the summer when biogenic NH3 emissions are largest. The annual contribution of the biogenic NH3 emissions was approximately 6% of the annual 2020 NH3 emissions. Estimated emission increases in the 2020 NEI for this sector compared to the 2017 NEI, model sensitivities to land use data, and future measurement and model needs will be discussed.