Turbulent Flux Measurements of the Near‐Surface and Residual‐Layer Small Particle Events

Abstract

According to recent field studies, almost half of the New Particle Formation (NPF) events occur aloft, in a residual layer, near the top of the boundary layer. Therefore, measurements of the meteorological parameters, precursor gas concentrations, and aerosol loadings conducted at the ground level are often not representative of the conditions where the NPFs take place. This paper presents new measurements obtained during the Turbulent Flux Measurements of the Residual Layer Nucleation Particles, conducted at the Southern Great Plains research site. Vertical turbulent fluxes of 3–10 nm‐sized particles were measured using a sonic anemometer and two condensation particle counters with nominal cutoff diameters of ≥ $\ge $3 nm and ≥ $\ge $10 nm mounted at the top of the 10‐m telescoping tower. Aerosol number size distribution (5–300 nm) was determined through the ground‐based Scanning Mobility Particle Sizers. The size selected (15–50 nm) particle hygroscopicity was derived with the Humidified Tandem Differential Mobility Analyzer. The ground level observations were supplemented by vertically‐resolved measurements of horizontal and vertical wind speeds and aerosol backscatter. The data analysis suggests that (a) turbulent flux measurements of 3–10 nm particles can distinguish between near‐surface and residual‐layer small particle events; (b) sub‐50 nm particles had a hygroscopicity value of 0.2, suggesting that organic compounds dominate atmospheric nanoparticle chemical composition at the site; and (c) current methodologies are inadequate for estimating the dry deposition velocity of sub‐10 nm particles because it is not feasible to measure particle concentration very near the surface, in the diffusion sublayer.

Spatio-temporal Variation of Meteorological Influence on PM2.5 and PM10 over Major Urban Cities of Bangladesh

“…Meteorology has been found to be one of the primary determinants of PM variation in the atmosphere (Liu and Cui, 2014;Trivedi et al, 2014). Studies have shown that meteorological parameters such as wind speed, temperature, relative humidity, solar radiation, rainfall, atmospheric boundary layer, pressure system play a significant role in explaining PM variation in the USA, China, and India (Islam et al, 2022a;Singh et al, 2021;Ilias et al, 2020;Wang et al, 2013). Hassan et al (2020) investigated the long-term PM relationship with meteorological parameters in Malaysia and identified that PM is strongly…”

Vertical Profiles of Particle Number Size Distribution and Variation Characteristics at the Eastern Slope of the Tibetan Plateau

“…The occurrence of explosive growth can result in a sudden augmentation of particles, with significant implications for air quality, climate, and human health. Understanding the underlying mechanisms and factors contributing to this explosive particle growth is vital for the accurate assessment of particle impacts [20]. Furthermore, these newly formed particles can potentially be activated as cloud condensation nuclei (CCN) after hours of growth [21].…”