Luc Lenain (Scripps Institution of Oceanography, United States); Bruce Cornuelle (Scripps Institution of Oceanography, United States); Sarah Gille (Scripps Institution of Oceanography, United States); Matthew Mazloff (Scripps Institution of Oceanography, United States)

The variability of sea surface height (SSH) is controlled by processes that span a broad range of spatial and temporal scales. At mesoscales and large submesoscales (300--15 km), the SSH spectrum is expected to be consistent with quasi-geostrophic (QG) turbulence theory and to be characterized by a quasi-linear spectral slope, with variance decaying toward higher wavenumbers. In contrast, at scales ranging from hundreds of meters to a few meters, SSH variability is dominated by surface gravity waves, with a spectrum characterized by one or more peaks at the wavenumber of the dominant waves. Because there is a clear scale separation between QG turbulence and surface wave dynamics, these two spectral bands have traditionally been explored independently. The Surface Water and Ocean Topography (SWOT) mission will for the first time resolve the 2D variability of SSH on scales at which some of these processes overlap; thus, there is a need to better understand the contribution of different physics to the SSH variability and consider the SSH spectrum as a continuum.

Here, we use measurements from airborne lidar altimetry to present a broadband view of the SSH wavenumber spectrum over scales ranging from hundreds of kilometers to a few meters, based on observations collected during a field campaign conducted off the California coast. The structure of the spectrum is discussed in light of the multiple processes that contribute to the SSH variability, such as geostrophically balanced motions, internal waves, infra-gravity waves, and surface waves. Additionally, we leverage the detailed knowledge of the 2-dimensional surface wave field measured by the airborne scanning lidar to assess the effects of different SSH averaging and sampling strategies during distinct surface wave and wind conditions.