Wednesday, 12 February 2003: 9:00 AM
Temperature Sensitivity of a Micrometerologically-Based Air-Sea Gas Transfer Parameterization
The air-sea exchange of climate relevant compounds (such as carbon dioxide) has come under increased scrutiny due to the uncertainty surrounding the total mass sequestration into the worlds’ oceans and due to the importance of these compounds to the potential effect on the Earth’s climate. The determination of the air-sea gas flux presents significant difficulties from a ship in the open ocean, although advances in measurement technology have recently been made. Although direct measurements are possible, it is imperative that methods of gas flux parameterization be developed in order to integrate to a regional-to-global scale estimation of the total gas transfer. The parameterization must contain descriptions of the physical mechanisms responsible for the gas flux and necessitate reasonable variables as inputs (i.e. variables which can be readily measured over large scales from in situ or remote sensors). Fairall et al. have presented one such parameterization recently in the literature, and work is on-going to make improvements. The most recent undertaking for this purpose is to focus in on the sea temperature inputs to the parameterization. A number of possible sea surface temperature inputs exist: 5-meter water intake temperature (for example, into a thermosalinigraph), the warm-layer temperature (from a floating thermistor), or a radiometrically measured temperature (at the cool skin in the tropics). As the actual skin temperature controls the mass flux, any measurement other than that of the skin requires a model of the thermal structure up to the surface. Using recently-acquired data sets from GasEx-2001 (and GasEx-1998), we will present results of a sensitivity study of the Fairall et al parameterization with respect to the input temperature. It is anticipated that significant differences in the estimated gas exchange will result from this comparison, and these results will be compared to directly-measured fluxes from that expedition.