Ocean Surface Wave Optical Roughness - Innovative Measurement and Modeling as part of the ONR Radiance in a Dynamic Ocean (RaDyO) DRI

Collaborators: Michael Banner (University of New South Wales)
Johannes R. Gemmrich (Institute of Ocean Sciences and University of Victoria)
Howard Schultz (University of Massachusetts, Amherst)

Our research RADYO Boathas provided details on the origin and evolution of microscale wave breaking that, when related to satellite scatterometry techniques  for measuring wave slope, can be used to estimate air-sea transfer globally. This link between microbreaking (and whitecapping) and wave slope requires details on initial wave growth, the evolution of microbreaking, and the modulation of capillary waves during microbreaking, and the dissipation of wave energy through microbreaking and whitecapping.

RADYO Equipment

C. Zappa led the examination of the transient nature of the slope features during microbreaking as part of the multi-disciplinary multi-investigator ONR Radiance in a Dynamic Ocean (RaDyO) DRI project in collaboration with M. Banner of the University of New South Wales, J. Gemmrich of the Institute of Ocean Sciences and University of Victoria, and H. Schultz of the University of Massachusetts, Amherst. The primary goals of RaDyO are:

  1. to examine the time-dependent oceanic radiance distribution in relation to a range of dynamic sea surface boundary layer processes, such as waves, surfactants, foam, amongst several others and
  2. to combine a radiance-based radiative transfer (RT) model with a surface wave model, validate the coupled model with field observations and to investigate the feasibility of inverting the coupled model to yield in formation on the surface boundary layer.

In this context, nonlinear interfacial roughness elements - sharp crested waves, breaking wave whitecaps as well as the foam, subsurface bubbles and spray they produce, contribute substantially to the distortion of the optical transmission through the air-sea interface. RADYO Hawaii Map These commonly occurring surface roughness features occur on a wide range of length scales, from the dominant sea state down to capillary waves. RADYO Santa Barbara Map Wave breaking signatures range from large whitecaps with their residual passive foam, down to the ubiquitous centimeter scale, microscale breakers that do not entrain air. C. Zappa led the field campaigns from R/P Flip during the RaDyO project in the Santa Barbara Channel in 2008 and off Hawaii in 2009 in for the remote sensing ocean surface wave optical roughness component that includes both innovative measurement (InfraRed, visible, and polarimetric imaging) and modeling. For more information about R/P Flip, click on the following schematic and video.