We use a combination of laboratory experiments, field measurements, theoretical analysis and numerical modeling to improve our understanding of air-sea interaction and ocean surface processes. Laboratory experiments are carried out in the Hydraulics Laboratory of SIO. Field measurements use moored or drifting instrument systems, airborne instruments, and sometimes fixed platforms on the continental shelf. We have conducted field experiments in the North Atlantic, the North and South Pacific, the North Sea, the Gulf of Mexico and Bass Strait, off the coast of Australia.
Experiments in the laboratory use modern optical, electromagnetic, and acoustical instrumentation to measure the evolution of velocity, temperature, surface-displacement and bubble concentration fields under wind-driven surface waves and mechanically generated breaking waves. Field measurements use in situ, tower-based, and airborne sensors to measure the same variables. When necessary, we build our own instruments or develop experimental techniques. Recent examples include the development of an acoustic instrument to measure bubble size distributions near the ocean surface, modular aerial sensing system (MASS) for motion-compensated imaging of the ocean surface, and the use of coherent acoustic Doppler techniques to measure wavenumber spectra of small-scale turbulence in the field. These instruments have also been used in support of near-shore dynamics and acoustics experiments off southern California beaches. Field experiments to measure electromagnetic bias have been conducted in support of radar altimetry of the ocean surface.
Another area of research is in theoretical and numerical modeling of nonlinear wave phenomena. These vary from nonlinear equatorial and coastal Kelvin waves ranging in scales from hundreds to thousands of kilometers, to gravity-capillary waves that are the smallest resolved features at the ocean surface having scales of centimeters to millimeters. Previous work in these areas has been concerned with the combined effects of nonlinearity and Coriolis forces on long internal waves which propagate on the thermocline, and understanding the role of nonlinearity and wind-forcing on the fine-scale structure of the ocean surface. The latter is very important in interpreting remote sensing measurements of the sea surface.