FATIMA: Fog And Turbulence Interactions in the Marine Atmosphere

Marine fog is defined as a turbulent air layer contiguous the ocean surface, laden with ~ 1-30 microns sized water droplets, characterized by Meteorological Optical Range (i.e., visibility) less than 1 km. Net deposition of water vapor on hygroscopic aerosols in near-saturated marine environments leads to marine fog through collusion of dynamic, thermodynamic and physicochemical processes. On larger scales, pioneering observations of Sir GI Taylor in the Grand Banks (Canadian north Atlantic) in the summer of 1913 posited that air-sea interactions accompanying the advection of warm, humid air over colder ocean is a major ingredient for the genesis of marine fog. Evolving fog droplets and their embryos (aerosols) are embedded in the smallest (Kolmogorov) eddies of atmospheric turbulence, and a host of two-phase microphysical process involving deposition/evaporation on/from the droplets, droplet surface tension, and eddy straining motions affect the genesis, growth, maturation and dissipation (i.e., lifecycle) of fog. This presentation will describe some major findings of a five-year (2021-26) multidisciplinary, multi-investigator, integrative project dubbed FATIMA on marine fog. It dived into fifteen decades of spatiotemporal scales undergirding the fog life cycle. Ship and land/platform based field observations in the Grand Banks, Sable Island (an islet in the region where warm Gulf Stream and cold Labrador waters mix) and Hibernia Oil Platform in 2022 as well as multi-ship and aircraft observations in the Yellow Sea (off-coast of the Republic of Korea) in 2023, all accompanied by high-resolution and numerical weather prediction (NWP) model simulations, elicited new meteorological and [bio]physicochemical processes associated with fog lifecycle. The results largely indicated that many extant concepts concerning the lifecycle of marine fog need a fundamental rethink.