UC Irvine

The deposition of soluble gases to the sea surface is physical process that impacts the biogeochemical cycling of sulfur, carbon, nitrogen, phosphorus and latent and sensible heat. Soluble atmospheric gases such as SO2, nitric acid and ammonia play key roles in global climate and air quality through their influence on aerosol and cloud formation, and tropospheric photochemistry. Direct air/sea flux measurements of soluble trace gases are rare and most of what we know stems from studies of latent and sensible heat. Lack of fundamental understanding of the physical controls of air/sea deposition of soluble gases limits the accuracy of models simulating some global biogeochemical cycles.

This study involved direct flux measurements of SO2, water vapor, sensible heat and momentum from the atmosphere to the sea surface. These measurements were done at piers located in San Diego, CA and Duck, NC. The goal of the study is to gain insight into the physical controls on soluble trace gas fluxes by comparing these measurements to each other and to various air/sea flux numerical parameterizations. The results of this analysis demonstrate that SO2 flux measurements are a viable approach to studying the physics of soluble trace gas flux over the ocean. Furthermore, the results show the transfer velocity of SO2 is ~ 20 % lower than that of water vapor. This reduction is attributed to resistance to gas transfer due to diffusion in the interfacial layer immediately above the sea surface. This study represents the first ever in situ measurement of diffusive resistance in the interfacial layer. The magnitude of diffusive resistance calculated from these measurements is ~ 18 % larger than the current gas transfer parameterizations (Fairall et al., 2000).