Characterizing Greater Houston's Aerosol by Air Mass During TRACER

Journal Article · Sat Jul 12 00:00:00 EDT 2025 · Journal of Geophysical Research. Atmospheres

DOI:https://doi.org/10.1029/2025JD043353· OSTI ID:2573826

Thompson, Seth A. ^[1]; Chen, Bo ^[1]; Matthews, Brianna H. ^[2]; Li, Ron ^[1]; Nowotarski, Christopher J. ^[1]; Rapp, Anita D. ^[1]; Brooks, Sarah D. ^[1]

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1. Texas A & M Univ., College Station, TX (United States)
2. Texas A & M Univ., College Station, TX (United States); Savannah River National Laboratory (SRNL), Aiken, SC (United States)

During the TRacking Aerosol and Convection interaction ExpeRiment (TRACER), a suite of aerosol and cloud measurements were made using the Texas A&M Rapid Onsite Atmospheric Measurement Van (ROAM-V) mobile instrument platform. Joint ROAM-V/radiosonde deployments focused on sampling polluted marine and continental air masses to understand summertime convection along and across the sea-breeze front as it propagated through Houston. The polluted marine air mass at Seawolf Park, Galveston, TX was defined by two characteristic aerosol populations. Although the background total particle concentrations averaged 2,500 cm⁻³, the air mass was also influenced by frequent but irregular periods of ship emission with significantly higher aerosol concentrations at times exceeding 34,000 cm⁻³. Ship emission influenced periods, typically lasting <10 min, contained smaller, less hygroscopic particles resulting in a 69% relative decline in cloud condensation nuclei (CCN) activated fraction at 1% supersaturation compared to background periods. Measurements in continental air masses northwest of Houston revealed an average aerosol concentration of 5,208 cm⁻³ with a κ value near 0.1 reasonably describing the CCN population, independent of particle size. In continental air masses, substantial differences in particle size and CCN activation over small distances (<42 miles between sites) suggest considerable site-to-site variability in addition to the expected day-to-day differences. This small-scale variability makes it difficult to generalize continental air mass aerosol properties. Both coastal and inland locations had effective ice nucleating particles, but inland deployments observed the warmest nucleation temperature at −15.6°C compared to −17.8°C close to the coast. These measurements can reduce uncertainties in regional convection allowing models to improve understanding of aerosol-cloud interactions.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Atmospheric Radiation Measurement (ARM) Archive
• Sponsoring Organization: USDOE Office of Science (SC), Biological and Environmental Research (BER)
• Grant/Contract Number: AC05-00OR22725; SC0021047
• OSTI ID: 2573826
• Journal Information: Journal of Geophysical Research. Atmospheres, Journal Name: Journal of Geophysical Research. Atmospheres Journal Issue: 14 Vol. 130; ISSN 2169-8996; ISSN 2169-897X
• Publisher: American Geophysical Union; Wiley
• Country of Publication: United States
• Language: English