Horizontal temperature length scales on the inner shelf due to breaking internal waves

Sea surface temperature maps of the inner shelf off of central California were produced from airborne thermal imaging during the 2017 ONR Inner Shelf DRI. A variety of temperature features resulting from fronts, internal waves, and surfzone processes were observed in the thermal imagery, with characteristic horizontal length scales associated with these mixing process. Of particular interest, are the range of sea surface temperature length scales that are related to internal wave breaking events and mixing processes in the water column. Internal waves propagating into the shallow inner shelf become nonlinear and break resulting in mixing of the stratified coastal water. At the air-water interface, these processes manifest as 10m-200m scale temperature features. Here, we calculate and examine these characteristic surface temperature length scales with the goal of relating surface signatures to stratification and mixing scales and intensity below the surface. We first explore methods to map the horizontal length scales associated with the internal wave fronts using Fourier spectral analysis and other techniques, such as support vector machines. We then compare these mapped surface scales with in situ measures of mixing length scales calculated from TKE dissipation rate estimates and vertical salinity and temperature profiles collected from drifters and ship surveys. One important outcome of this work will be to assess the feasibility of predicting subsurface stratification and mixing from surface thermal remote sensing.