Project Title:  A Fetch Dependent Gas Transfer Velocity

Year: 2020

Principal Investigators:  Seth Zippel (AOPE) ( and Matthew Long (MCG)

Affiliations: Woods Hole Oceanographic Institution

Abstract: Air/water exchanges of gasses are important for both local biogeochemical cycles and for large scale climate change. Typically, these gas exchanges are parameterized as a function of wind speed without any direct consideration of the local turbulence or surface waves that are physically relevant to these transfers. As such, these parameterizations fail in coastal areas where waves are limited by fetch and modified by local currents and bathymetry. We propose a fetch-dependent gas transfer velocity based on existing theory for near surface turbulence and wave growth. We propose to test this new parameterization with local measurements in Waquoit Bay under a range of fetch and wind speeds. This parameterization will help the biogeochemical community estimate gas fluxes with simple inputs (locally measured wind speed and fetch from Google maps) without a need for measurements of complex turbulent dynamics. With increasing attention to the large role that coastal and estuarine environments play in global biogeochemical cycling, there is a growing consensus that better estimates of air/water exchange are needed to accurately describe their importance, as well as how this may be altered due to local anthropogenic influence and global climate change.