Quantifying aerosol size distributions and their temporal variability in the Southern Great Plains, USA

Abstract. A quality-controlled, 5-year dataset (2009–2013) of aerosol number size distributions (particles with diameters (D p ) from 7 nm through 14 μm) was developed using observations from a scanning mobility particle sizer, aerodynamic particle sizer, and a condensation particle counter at the Department of Energy's Southern Great Plains (SGP) site. This dataset was used for two purposes. First, typical characteristics of the aerosol size distribution (number, surface area, and volume) were calculated for the SGP site, both for the entire dataset and on a seasonal basis, and size distribution lognormal fit parameters are provided. While the median size distributions generally had similar shapes (4 lognormal modes) in all the seasons, there were some significant differences between seasons. These differences were most significant in the smallest particles (D p p  > 800 nm). Second, power spectral analysis was conducted on this long-term dataset to determine key temporal cycles of total aerosol concentrations, as well as aerosol concentrations in specified size ranges. The strongest cyclic signal was associated with a diurnal cycle in total aerosol number concentrations that was driven by the number concentrations of the smallest particles (D p p between 140 nm and 800 nm, with peak concentrations occurring in the overnight hours, which were primarily associated with both nitrate and organic aerosol cycles. Weaker cyclic signals were observed for longer time scales (days to weeks) and are hypothesized to be related to the time scales of synoptic weather variability. The strongest periodic signals (3.5-5-day and 7-day cycles) for these longer time scales varied depending on the season, with no cyclic signals and the lowest variability in the summer.