Observational efforts to understand aerosol-cloud interactions at high latitudes

Gijs de Boer(1)(2), Matthew Shupe(1)(2), Timothy Garrett(3), Chaunfeng Zhao(4), Dave Turner(2)

Abstract
Of the uncertainties surrounding our understanding of global climate, one of the largest involves the effects of aerosol particles on cloud radiative transfer and precipitation intensity. Due to limited profiling of aerosol properties, traditionally aerosol-cloud interactions are statistically evaluated using surface aerosol measurements as a proxy for aerosol at cloud height. At low- and mid-latitudes, clouds often form atop a well-mixed atmospheric boundary layer, meaning that the use of surface-based aerosol measurements may not be unreasonable. At high latitudes, however, the atmosphere is often very stable. This stability limits vertical mixing of aerosols, meaning aerosol properties (e.g. number, hygroscopicity, scattering, size) observed at the Earth’s surface may be very different from those at cloud height. This limitation makes it challenging to interpret previous efforts to understand the impacts of aerosols on liquid-containing Arctic clouds (e.g. Lubin and Vogelmann, 2006; Garrett and Zhao, 2006). In this presentation, I will present recent and ongoing efforts to better understand relationships between aerosol particles and clouds. This will include evaluation of in-situ and ground-based remote sensing datasets to evaluate the impact of different atmospheric stability regimes on the vertical distribution of aerosol. Additionally, I will provide updated estimates of aerosol-cloud interactions in thin, liquid-containing Arctic clouds, taking into account the possible disconnect between surface-based aerosol and those at cloud height. Finally, I will provide insight into upcoming field campaigns using unmanned aircraft that should provide additional details on the vertical distribution of aerosol at high latitudes.