Air-Water Gas Transfer in Coastal Waters
Abstract
The research was centered around a new experimental technique that uses heat as a proxy tracer to measure the air-sea gas exchange rate. The transfer rate for heat in water is measured by using a known heat flux density and measuring the temperature difference across the aqueous boundary layer. In contrast to geochemical methods that are based on mass balances and that have a slow response time in the order of days to weeks due to the larger vertical scales (typically the depth of the mixed layer), the controlled flux density gives an instantaneous picture' of the transfer process. Hence, direct insight into the transport processes right at the air-water interface is obtained through quantitative analysis of infrared image sequences of the water surface. Together with physical modeling of the underlying transfer processes, this passive infrared radiometry technique allowed the computation of the transfer rates directly from the statistical surface temperature distributions without artificial heating of the water surface. The influence of wind forcing, short wind waves, and surfactants on the air-sea gas transfer in coastal waters was studied in field two experiments. The measurements include the air-sea gas transfer rates with a temporal resolution in order of minutes, the air friction velocity, water currents and turbulence, air and water temperatures, visible and infrared radiative fluxes, the visco-elastic properties of surface films, and wave number-frequency spectra of short wind waves. The measurements of the air-sea gas exchange rates with our instruments were combined with concentration measurements of carbon dioxide and dimethyl sulfide in the sea and the atmosphere, and direct flux measurements of carbon dioxide using the eddy correlation technique.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 30, 2000
- Accession Number
- ADA392925
Entities
People
- Bernd Jaehne
Organizations
- Scripps Institution of Oceanography