Sea State and Boundary Layer Stability Limit Sea Spray Aerosol Lifetime
over the Southern Ocean
Abstract
A data set of concurrent measurements of sea spray aerosol
concentration, wind speed, sea state, and air and water temperature was
acquired across all sectors of the Southern Ocean during the Antarctic
Circumnavigation Expedition (Austral summer 2016/2017). In addition to
the established dependence on wind speed, our observations demonstrate
that sea spray aerosol concentrations depend on sea state and the
stability of the marine boundary layer. Besides driving sea spray
emissions, wind speed and sea state strongly influence the deposition
onto the ocean surface and thus aerosol lifetime even for smaller
particles. Stable atmospheric conditions allow a typical lifetime of
up to 4 days, while tropospheric air entrainment in unstable conditions
reduces the residence time of sea spray aerosol in the marine boundary
layer to less than 2 days.