NPFSTUDY

The formation of 1 nm-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 (Kerminen et al. 2005; Kuang et al. 2009; Lihavainen et al. 2003; Merikanto et al. 2010). 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 (Chen et al. 2018; Wang et al. 2016). Furthermore, these vertically-resolved measurements are needed in order to: connect the atmospheric conditions that drive atmospheric new particle formation (NPF) with large-scale boundary layer transport processes and meteorology and evaluate the extent to which surface-based aerosol measurements are representative of the atmospheric aerosol aloft. Vertically-resolved profiles of the atmospheric aerosol cluster concentration and size distribution will be obtained via the deployment of a set of two condensation particle counters (CPCs) on the ARM Tethered Balloon System (TBS). Proposed measurements will take place at the Central Facility of the ARM SGP site, which is an ideal location for studying NPF due to the frequent observations of NPF at the surface and due to observations of NPF occurring aloft (Chen et al. 2018; Hodshire et al. 2016). The two CPCs that will be modified to detect aerosol down to 3 nm and below according to established protocols (Kuang et al. 2012). The proposed study is a continuation of the VNATS-SGP (2019) study which looked at NPF occurring in the summer. This proposal distinguishes itself from VNATS 2019 in two key aspects: [1] it focuses on NPF occurring in the spring, the season during which peak NPF strength and frequency has been observed at the SGP, and [2] it will deploy a butanol-based CPC in conjunction with a water CPC in order to probe the composition of newly formed aerosol via composition-dependent CPC detection.

Timeline