Identifying a regional aerosol baseline in the Eastern North Atlantic using collocated measurements and a mathematical algorithm to mask high submicron number concentration aerosol events

Abstract

Abstract. High time-resolution measurements of in situ aerosol and cloud properties provide the ability to study regional atmospheric processes that occur on timescales of minutes to hours. However, one limitation to this approach is that continuous measurements often include periods when the data collected are not representative of the regional aerosol. Even at remote locations, submicron aerosols are pervasive in the ambient atmosphere with many sources. Therefore, periods dominated by local aerosol should be identified before conducting subsequent analyses to understand aerosol regional processes and aerosol-cloud interactions. Here, we present a novel method to validate the identification of regional baseline aerosol data by applying a mathematical algorithm to the data collected at the U.S. Department of Energy's (DOE) Atmospheric Radiation Measurement (ARM) User Facility in the Eastern North Atlantic (ENA). The ENA Central facility (C1) includes an Aerosol Observing System (AOS) for the measurement of aerosol physical, optical, and chemical properties at time resolutions from seconds to minutes. A second temporary Supplementary facility (S1), located ~ 0.75 km from C1, was deployed for ~ 1 year during the Aerosol and Cloud Experiments (ACE-ENA) campaign in 2017. First, we investigate the local aerosol at both locations. We associate periods of high submicron number concentration (Ntot) in the fine mode Condensation Particle Counter (CPC) and size distributions from the Ultra-High Sensitivity Aerosol Spectrometer (UHSAS) as a function of wind direction using a meteorology sensor with local sources. Elevated concentrations of Aitken mode (

Automated identification of local contamination in remote atmospheric composition time series

“…McNabola et al (2011) applied baseflow separation techniques, such as low-pass filters or moving interval filters, known from streamflow hydrology, to separate background concentrations in urban PM 10 measurements and compared the result to background PM 10 measurements. Gallo et al (2020) developed a method to retrieve the regional aerosol number concentration baseline at the Eastern North Atlantic (ENA) Atmospheric Radiation Measurement (ARM) user facility from the US Department of Energy. The ENA Aerosol Mask (ENA-AM) identifies data points, which exceed the standard deviation of the data below the median of a 1-month period by more than a factor of α.…”

Exploring the Constraints on Simulated Aerosol Sources and Transport Across the North Atlantic With Island‐Based Sun Photometers

“…While previous studies have investigated the transport of aerosol species westward across the Equatorial Atlantic (e.g., Barkley et al, 2019) or the influence of specific events on transported species (Ancellet et al, 2016), we focus here on the North Atlantic with particular interest in understanding the long‐term sources of transported aerosol to continental Europe. Analyses of in situ observations indicate the importance of long‐range transport in the North Atlantic (e.g., Gallo et al, 2020; Zheng et al, 2020); however, there has been limited exploration and evaluation of model representations of aerosols over this region. Constraining this trans‐Atlantic transport is central to characterizing aerosol source contributions to the degradation of air quality over Europe as well as investigating how these aerosol species influence climate and biogeochemistry over the ocean (e.g., Carslaw et al, 2013; Foltz & McPhaden, 2008; Penner et al, 1994).…”