Coupled air quality and boundary-layer meteorology in Western U.S. basins during winter: Design and rationale for a comprehensive study

Authors: HALLAR, GANNET - University Of Utah; BROWN, STEVE - National Oceanic & Atmospheric Administration (NOAA); CROSMAN, ERIK - West Texas A & M University; BARSANTI, KELLEY - University Of California; CAPPA, CHRIS - Uc Davis Medical Center; FALOONA, IAN - Uc Davis Medical Center; FAST, JEROME - Pacific Northwest National Laboratory; HOLMES, HEATHER - University Of Nevada; HOREL, JOHN - University Of Utah; LIN, JOHN - University Of Utah; MIDDLEBROOK, ANN - National Oceanic & Atmospheric Administration (NOAA); MITCHELL, LOGAN - University Of Utah; MURPHY, JENNIFER - University Of Toronto; WOMACK, CAROLINE - National Oceanic & Atmospheric Administration (NOAA); ANEJA, VINEY - North Carolina State University; BAASANDORJ, MUNKHBAYAR - University Of Utah; BAHREINI, ROYA - University Of California; BANTA, ROBERT - National Oceanic & Atmospheric Administration (NOAA); BRAY, CASEY - North Carolina State University; BREWER, ALAN - National Oceanic & Atmospheric Administration (NOAA); CAULTON, DANA - University Of Wyoming; DE GOUW, JOOST - University Of Colorado; DE WEKKER, STEPHAN - University Of Virginia; FARMER, DELPHINE - Colorado State University; GASTON, CASSANDRA - University Of Miami; HOCH, SEBASTIAN - University Of Utah; HOPKINS, FRANCESCA - University Of California; KARLE, NAKUL - University Of Texas - El Paso; KELLY, JAMES - Us Environmental Protection Agency (EPA); KELLY, KERRY - University Of Utah; LAREAU, NEIL - University Of Nevada; LU, KEDING - Peking University; MAULDIN III, ROY - National Center For Atmospheric Research (NCAR); MALLIA, DEREK - University Of Utah; MARTIN, RANDAL - University Of Utah; MENDOZA, DANIEL - University Of Utah; OLDROYD, HOLLY - Uc Davis Medical Center; PICHUGINA, YELENA - National Oceanic & Atmospheric Administration (NOAA); PRATT, KERRI - University Of Michigan; SAIDE, PABLO - University Of California (UCLA); Silva, Philip - Phil; SIMPSON, WILLIAM - University Of Alaska; STEPHENS, BRITTON - National Center For Atmospheric Research (NCAR); STUTZ, JOCHEN - University Of California (UCLA); SULLIVAN, AMY - Colorado State University

Submitted to: Bulletin of the American Meteorological Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/9/2021
Publication Date: 10/1/2021
Citation: Hallar, G.A., Brown, S., Crosman, E., Barsanti, K., Cappa, C., Faloona, I., Fast, J., Holmes, H., Horel, J., Lin, J., Middlebrook, A., Mitchell, L., Murphy, J., Womack, C.C., Aneja, V., Baasandorj, M., Bahreini, R., Banta, R., Bray, C., Brewer, A., Caulton, D., de Gouw, J., De Wekker, S., Farmer, D.K., Gaston, C.J., Hoch, S., Hopkins, F., Karle, N., Kelly, J., Kelly, K., Lareau, N., Lu, K., Mauldin III, R.L., Mallia, D., Martin, R., Mendoza, D., Oldroyd, H., Pichugina, Y., Pratt, K.A., Saide, P., Silva, P.J., Simpson, W., Stephens, B., Stutz, J., Sullivan, A. 2021. Coupled air quality and boundary-layer meteorology in Western U.S. basins during winter: Design and rationale for a comprehensive study. Bulletin of the American Meteorological Society. E2012-E2033. https://doi.org/10.1175/BAMS-D-20-0017.1.
DOI: https://doi.org/10.1175/BAMS-D-20-0017.1

Interpretive Summary: Poor air quality episodes during wintertime in air basins often result in elevated particulate matter concentrations. These episodes are dependent on the emissions in a particular basin (urban/agricultural) and wintertime meteorology that causes stagnation events. The impact of and interplay of chemistry and meteorology creates major uncertainties in how best to address these air quality episodes. A strategy session of scientists took place to discuss important features of a future field research campaign to address these issues. The session concluded that a comprehensive airborne and ground based field campaign should be conducted in western U.S. air basins, focused on the San Joaquin Valley of California and the valleys of Utah (Cache, Salt Lake, and Utah) and with significant focus on both meteorology and chemistry.

Technical Abstract: Winter episodes of high aerosol concentrations occur frequently in urban and agricultural basins and valleys across the globe. These episodes often arise due to the development of persistent cold-air pools (PCAPs). Current regulatory actions are not effectively targeting the appropriate precursor emissions in winter basins due to a gap in understanding of coupled chemical-meteorological interactions to produce highly polluted conditions. With this challenge at the forefront, a workshop was organized in September 2019 with the goal of planning a future research campaign in the winter of 2022/2023 to investigate mountain basins of the western U.S. Approximately 120 people participated in the workshop at the University of Utah, representing 50 institutions and 5 countries. As summarized in this article, the workshop outlined the rationale and design for a comprehensive study coupling atmospheric chemistry and boundary-layer meteorology within western U.S. wintertime basins. It was concluded that a comprehensive study should focus on two regions with contrasting aerosol chemistry: the three populated valleys within Utah (Salt Lake Valley, Utah, and Cache) and the San Joaquin Valley (SJV). This paper highlights the need to acquire chemically comprehensive datasets using airborne platforms with extensive range coupled to extensive surface measurements, focusing on the ability to sample the surface layer with high vertical resolution. No prior field campaign has provided the breadth and depth of contemporaneous observations at the surface and aloft necessary to analyze the meteorological-chemical linkages outlined here nor serve as input to or validation for atmosphere-chemistry models.