Recent Developments in Air-Sea Interaction Research: Laboratory, Field and Modeling Studies (Core Science Lecture)

Over the last thirty years progress in understanding processes of air-sea interaction (ASI) has benefitted greatly from our ability to conduct experiments in the field with the precision that before was often restricted to the laboratory. With the developments in GPS technology and motion sensing, in situ and remote sensing techniques that were once confined to the laboratory can now be used to conduct studies of the marine atmospheric boundary layer (MABL), the kinematics and statistics of breaking, and surface and Langmuir turbulence from stable platforms like R/P FLIP and aircraft. Measurements of directional wavenumber spectra, that are central to our ability to develop improved numerical models of wave evolution, air-sea fluxes and marine boundary layer processes dependent on Stokes drift can be precisely measured from aircraft using scanning lidars resolving down to sub-meter wavelengths. Boundaries between equilibrium and saturation wave spectra can be measured. Meanwhile fundamental processes, that can only be reproduced in the laboratory, can be used with field measurements to develop models and test our understanding and prediction of atmosphere-ocean interaction. For example, simple scaling of dissipation due to breaking, confirmed in a number of laboratory facilities, has been incorporated into numerical wind-wave models to predict breaking statistics which could then be tested against field data. Recent direct two-phase numerical simulations of wave breaking have supported the basic dissipation scaling argument and extended it into the gravity-capillary range, while theory has predicted the associated circulation generated by breaking. Ship-launched and recovered unmanned aerial vehicles (UAVs), instrumented for ASI research, now enable extended spatio-temporal coverage from research vessels without the problems of flow interference often encountered with ship-mounted instruments. In this talk I will review these recent developments and comment on some of the challenging problems that will keep the field active for the coming decades.