Preprints
https://doi.org/10.5194/egusphere-2023-601
https://doi.org/10.5194/egusphere-2023-601
12 Apr 2023
 | 12 Apr 2023
Status: this preprint is open for discussion and under review for Atmospheric Chemistry and Physics (ACP).

Measurement report: Airborne measurements of NOx fluxes over Los Angeles during the RECAP-CA 2021 campaign

Clara M. Nussbaumer, Bryan K. Place, Qindan Zhu, Eva Y. Pfannerstill, Paul Wooldridge, Benjamin C. Schulze, Caleb Arata, Ryan Ward, Anthony Bucholtz, John H. Seinfeld, Allen H. Goldstein, and Ronald C. Cohen

Abstract. Nitrogen oxides (NOx ≡ NO + NO2) are involved in most atmospheric photochemistry, including the formation of tropospheric ozone (O3). While various methods exist to accurately measure NOx concentrations, it is still a challenge to quantify the source and flux of NOx emissions. We present airborne measurements of NOx and winds used to infer the emission of NOx across Los Angeles. The measurements were obtained during the research aircraft campaign RECAP-CA (Re-Evaluating the Chemistry of Air Pollutants in CAlifornia) in June 2021. Geographic allocations of the fluxes are compared to the NOx emission inventory from the California Air Resources Board (CARB). We find that the NOx fluxes have a pronounced weekend effect and are highest in the Eastern part of the San Bernardino valley. The comparison of the RECAP-CA and the modeled CARB NOx fluxes suggest the modeled emissions are too high near the coast and in downtown Los Angeles and too low further inland in the Eastern part of the San Bernardino valley.

Clara M. Nussbaumer et al.

Status: open (until 07 Jun 2023)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse

Clara M. Nussbaumer et al.

Data sets

Supporting data for: Measurement report: Airborne measurements of NOx fluxes over Los Angeles during the RECAP-CA 2021 campaign Clara M. Nussbaumer, Bryan K. Place, Qindan Zhu, Eva Y. Pfannerstill, Paul Wooldridge, Benjamin C. Schulze, Caleb Arata, Ryan Ward, Anthony Bucholtz, John H. Seinfeld, Allen H. Goldstein, and Ronald C. Cohen https://doi.org/10.5281/zenodo.7786409

Clara M. Nussbaumer et al.

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Short summary
NOx is a precursor to hazardous tropospheric ozone and can be emitted from various anthropogenic sources. It is important to quantify NOx emissions in urban environments in order to improve the local air quality which still remains a challenge as sources are heterogeneous in space and time. In this study, we calculate NOx emissions over Los Angeles based on aircraft measurements in June 2021 and compare them to a local emission inventory which we find to mostly overpredict the measured values.