HR: 0800h
AN: B41B-0190    [Abstracts]
TI: How Accurately Can One Measure Air-Sea Gas Exchange Velocities Using Eddy Covariance?
AU: * Huebert, B J
EM: huebert@hawaii.edu
AF: University of Hawaii, Dept. of Oceanography, Honolulu, HI 96822 United States
AU: Blomquist, B W
EM: blomquis@hawaii.edu
AF: University of Hawaii, Dept. of Oceanography, Honolulu, HI 96822 United States
AB: The eddy covariance (EC) method for measuring air-sea gas fluxes offers a tremendous potential for improving our understanding of the controls on all air-sea gas fluxes. Observation intervals of less than an hour make it possible to see - on the same day, with the same winds, weather, and sun - how much the flux changes when a research ship encounters a surface slick, or when the wave slope or bubble spectrum changes significantly. This sub-hour time response enables very nicely constrained studies of the factors controlling fluxes. We have demonstrated the ability to make DMS flux measurements in times less than an hour, enabling DMS to be used as a model for the fluxes of other carbon-containing gases. Under some conditions (e.g., INTEX), DMS itself dominates the air-sea exchange of carbon. The flux-related quantity most easily generalized to other gases (CO2, CH4, CO, etc.) and conditions is the exchange velocity, k, which is the measured flux divided by the measured sea-air concentration difference. The uncertainty in the kDMS we derive is thus controlled in part by the frequency and uncertainty of the sea water DMS concentrations measured in parallel with our DMS fluxes. EC measurements from ships involve many potential sources of error: the response speed of chemical sensors, flow distortion by the ship, ship-motion contamination of wind measurements, covariance uncertainties, calibration errors, and the sea water DMS uncertainty. Based on estimates of each of these errors for DMS, we argue that a k uncertainty of a few tens of percent is achievable for hourly values.
DE: 0312 Air/sea constituent fluxes (3339, 4504)
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 0428 Carbon cycling (4806)
DE: 0452 Instruments and techniques
DE: 4504 Air/sea interactions (0312, 3339)
SC: Biogeosciences [B]
MN: Fall Meeting 2005