Exploring local and long-range aerosol source contributions to summertime CCN in Southern Greenlandic fjord systems

The Greenland Ice Sheet (GrIS) discharges ~1000 Gt yr^-1 of freshwater into Arctic coastal oceans in the form of meltwater runoff and glacial discharge, with the majority entering the ocean via fjords. Fjordic ecosystems lie at the nexus of various facets of the environment, the ocean, land, cryosphere, atmosphere and biosphere, all of which are especially sensitive to climate change exacerbated by the rising global temperature. With the increase in length and intensity of the summer melt periods, both marine and land-terminating glaciers are slowly receding leaving altered downstream ecosystems in their wake. As glaciers recede, glacial outwash plains become exposed and the potential of sediment aerosolization increases. Concurrently, triggered by increasing melt-water discharge, marine biological productivity is changing, due to the evolving fjord dynamics, stratification, and composition.  Hence, the composition and sources of atmospheric aerosols responsible for the cloud formation in this region are evolving and we expect this to influence both the Cloud Condensation Nuclei (CCN) and Ice Nucleating Particle (INP) populations. In addition to natural aerosols sources, also local anthropogenic activities can contribute to the CCN and INP populations. Furthermore, distant emissions e.g., from north American boreal forest fires, occasionally reach Greenlandic Fjord systems and can have significant impact on the aerosol properties. 

In this presentation we aim to provide an overview of the processes which influence aerosol populations in Greenlandic fjord systems during Arctic summer. We will show results from a comprehensive and extensive field campaign in the Kujalleq province of Southern Greenland (60.91°N, 46.05°W) in June-August 2023. We will present aerosol size distributions, particle number concentrations, and scattering and absorption measurements from both ground-based and tethered-balloon measurement platforms. We will explore the following questions:

• What are the local and regional sources of aerosols leading to the formation of CCN in Southern Greenland?
• What is the current contribution of anthropogenic activities to the aerosol budget and how does this compare to the contribution from natural sources?
• How do long-range transport, new particle formation and ground-level fog events affect the concentration and vertical distribution of aerosols and subsequent CCN formation?