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Applying Multiple Approaches within CMAQ to Improve the Representation of Lightning NOx Emissions Across the Northern Hemisphere
Citation:
Madden, James, D. Kang, J. East, G. Sarwar, C. Hogrefe, R. Mathur, AND B. Henderson. Applying Multiple Approaches within CMAQ to Improve the Representation of Lightning NOx Emissions Across the Northern Hemisphere. 103rd Annual AMS Conference, Denver, CO, January 08 - 12, 2023.
Impact/Purpose:
Lightning is one of the major natural sources to produce nitrogen oxides (NOx) which contribute to the tropospheric ozone (O3) formation and other air quality related processes. It is important to incorporate the most up-to-date science and observational data for lightning NOx productions in time and space in air quality models and evaluate air quality model's performance. This research is to investigate the impact of LNOx emissions on air quality over the Northern Hemisphere using lightning flash data from ground-based networks and the climatological LNOx emissions in the Global Emissions InitiAtive (GEIA) dataset.
Description:
In line with the theme of the 2023 AMS Annual Meeting of data driving science and informing decisions, this presentation relates to the representation, and increasing relevance, of lightning NOx (LNOx) emissions in numerical studies of atmospheric composition, air pollution, and surface deposition. To account for this important source of tropospheric NOx, chemical transport models, such as the Community Multiscale Air Quality (CMAQ) model, incorporate lightning data to generate LNOx emissions and simulate the subsequent impacts of those LNOx emissions on various pollutants of concern (e.g., ozone). The CMAQ model can accurately represent LNOx emissions using hourly input lightning flash data from the National Lightning Detection Network (NLDN), a dense, high lightning detection efficiency network with coverage over the contiguous U.S. (CONUS). For hemispheric to global applications, the World Wide Lightning Location Network (WWLLN) is an attractive alternate source of lightning flash data, even with its lower lightning detection efficiency compared to NLDN. Besides the in-line calculations that use these hourly lightning flash data, CMAQ can also represent LNOx emissions using climatological datasets, such as the Global Emissions InitiAtive (GEIA) inventory. To resonate with the theme of the AMS Annual Meeting, we examine how varying LNOx emissions configurations impact the simulated atmospheric composition and near-surface air quality of the Northern Hemisphere. Four LNOx configurations are devised for the year 2016: one with no LNOx emissions; one using monthly LNOx climatology from the GEIA inventory; one using hourly WWLLN flash data; and a final one using a “scaled” version of WWLLN, which contains adjustments that reflect the NLDN monthly climatology over the CONUS that is then extrapolated over the Northern Hemisphere. Country-specific and latitudinal analyses show that the varying LNOx configurations (i.e., GEIA, WWLLN, and the scaled WWLLN with NLDN climatology) lead to large regional differences in LNOx emissions, particularly during summer months, when lightning activity is most active. Additionally, we demonstrate the value of using LNOx emissions data for hemispheric applications, specifically through comparisons of simulated results against observed surface concentrations, deposition fluxes, vertical ozone profiles, satellite products, and aircraft-based measurements.