A Role for Altimeter Radars in Gas Exchange Studies
Nelson Frew(1) , David Glover(1) , and Scott McCue(1)
Woods Hole Oceanographic Institution,
360 Woods Hole Rd.,
Woods Hole MA 02543,
Accurate estimates of air-sea transfer rates of radiatively active gases are needed for studies of regional and global gas cycling and for climate change studies. However, estimates using traditional wind speed – gas transfer velocity parameterizations vary by a factor of 2-3, contributing significantly to error budgets in global modeling of gas exchange and the carbon cycle. A decade of research has shown the utility of sea surface roughness, represented by the mean square slope (mss) due to gravity-capillary scale waves, as a proxy for gas exchange. Normalized backscatter of altimeter radars can be used in scattering models to estimate mss by combining coordinated ship-based measurements of mss with satellite overflights. These coordinated field experiments over the last decade have begun to provide the data necessary to calibrate mss estimates from altimeter radars. Now we have developed this technique into an alternative approach for assessing global gas transfer velocity fields remotely. Our presentation will trace the evolution of this concept from key laboratory and in situ observations to remote sensing observations and construction of a decade-long time series from the TOPEX and Jason-1 data streams.