Vertically-Resolved Nanoparticle Concentrations Observed at the ARM Southern Great Plains Site

Abstract:

The formation of 1 nanometer-sized atmospheric clusters is an important environmental nano-scale process, with field measurements and modeling studies indicating that freshly nucleated particles can contribute significantly to the global population of aerosol and cloud condensation nuclei. While there have been an increasing number of atmospheric cluster measurements from surface-based platforms, there have been very few measurements of the vertically-resolved ambient cluster size distribution from aerial platforms. Vertically-resolved atmospheric cluster measurements are needed because aerosol formation in the upper troposphere may be a significant source of cloud condensation nuclei. Furthermore, these vertically-resolved measurements are needed in order to: [1] connect the atmospheric conditions that drive atmospheric new particle formation (NPF) with large-scale boundary layer transport processes and meteorology, and [2] evaluate the extent to which surface-based aerosol measurements are representative of the atmospheric aerosol aloft. In order to develop process-level understanding for the formation and growth of atmospheric aerosol aloft, vertically-resolved measurements of the atmospheric nanoparticle number concentration were obtained at the ARM Southern Great Plains (SGP) measurement site, where frequent NPF is observed at the surface. Vertically-resolved measurements were obtained via a pair of battery-powered, water-based condensation particle counters (CPCs) at two different cut-sizes, deployed from the ARM tethered balloon system. These vertically-resolved observations were combined with local observations of meteorology and cloud conditions to contextualize the atmospheric conditions and transport processes that control aerosol formation and growth aloft at the SGP.