From Aerosol to Climate Patterns: A Multi-Scale Study of Marine Fog Variability in Atlantic Canada and the Central Arctic

Abstract

Marine fog is a complex and under-constrained phenomenon shaped by interactions between aerosols, ocean conditions, and atmospheric structure. This thesis examines fog formation across two contrasting regions: the CCN-rich but increasingly unstable northwest Atlantic and the pristine, CCN-limited Central Arctic. Using in situ field observations, long-term climatology, and reanalysis data, the work identifies the key physical mechanisms controlling fog microphysics and variability.

Field campaigns in Nova Scotia (2016) and the Central Arctic (2018) revealed distinct activation regimes. Nova Scotia fog featured activation diameters of 250–400 nm, reflecting an accumulation-mode aerosol population and size-dependent scavenging. Arctic fog instead activated ultrafine Aitken-mode particles (20–40 nm) under high supersaturations (0.3–1.0%) in a CCN-scarce environment, highlighting strong aerosol–supersaturation coupling.

A 1953–2019 Sable Island analysis shows a shift from synoptic pressure control toward local thermodynamic regulation linked to warming SSTs. Together, these results illustrate two limiting fog regimes and underscore the need for models that capture both microphysical activation and evolving climate drivers.