PARAMETERIZATION FOR THE LOCAL GAS TRANSFER VELOCITY OF CARBON DIOXIDE AT THE SURFACE OF WIND WAVES

Abstract

A laboratory experiment was made to parameterize the gas transfer velocity of CO₂ at the surface of wind waves. The local flux of CO₂ was estimated at several fetches by fitting a logarithmic law to the vertical profile of the concentration of CO₂ in the air. The dissolved CO₂ concentration was measured by using a gas-liquid equilibrator made of hydrophobic porous tube. The local gas transfer velocity was obtained form the results of the flux and dissolved CO₂ measurements. For the parameterization, two dimensionless parameters, gx/μ*_w² and μ*_w³/gv_w were derived from a dimensional analysis, where μ*_w is the friction velocity on the water side, g the gravitational acceleration, x the fetch and V_w the kinematic viscosity for the water. On the basis of the experimental results and the dimensional analysis, we proposed a new empirical formul a for the gas transfer velocity of CO₂ in consideration of the fetch dependence.