An air quality and boundary layer dynamics analysis of the Los Angeles basin area during the Southwest Urban NO x and VOCs Experiment (SUNVEx)

作者：Edward Strobach, Sunil Baidar, Brian Carroll, Steven S. Brown, Kristen Zuraski, Matthew M. Coggon, Chelsea E. Stockwell, Lu Xu, Yelena L. Pichugina, W. Alan Brewer, C. Warneke, Jeff Peischl, J. B. Gilman, Brandi McCarty, Maxwell Holloway, Richard D. Marchbanks · 发表于：Atmospheric chemistry and physics · 年份：2024 · DOI：10.5194/acp-24-9277-2024 · 被引用次数：6 · 研究领域：Atmospheric chemistry and aerosols、Atmospheric aerosols and clouds、Air Quality Monitoring and Forecasting

Abstract. The NOAA Chemical Sciences Laboratory (CSL) conducted the Southwest Urban NOx and VOCs Experiment (SUNVEx) to study emissions and the role of boundary layer (BL) dynamics and sea-breeze (SB) transitions in the evolution of coastal air quality. The study presented utilizes remote sensing and in situ observations in Pasadena, California. Separate analyses are conducted on the synoptic conditions during ozone (O3) exceedance (>70 ppb) and non-exceedance (<70 ppb) days, as well as the fine-structure variability of in situ chemistry measurements during BL growth and SB transitions. Diurnal analyses spanning August 2021 revealed a markedly different wind direction during evenings preceding O3 exceedance (northerly) versus non-exceedance (easterly) days. Increased O3 occurred simultaneously with warmer and drier conditions, a reduction in winds, and an increase in volatile organic compounds (VOCs) and fine particulate matter (PM2.5). While the average BL height was lower and surface pressure was higher, the day-to-day variability of these quantities led to an overall weak statistical relationship. Investigations focused on the fine-structure variability of in situ chemistry measurements superimposed on background trends were conducted using a novel multivariate spectral coherence mapping (MSCM) technique that combined the spectral structure of two or more independent measurements through a wavelet analysis as reported by maximum-normalized scaleograms. A case study w...