Multi-Scale Model-Driven Sampling with Autonomous Systems at a National Littoral Laboratory: Turbulence Characterization from an AUV
My long term goal is to utilize turbulence measurements obtained from small Autonomous Underwater Vehicle (AUV) based sensors as the subgrid characterization tool in combined coastal ocean observation/prediction networks. OBJECTIVES I wish to use AUV-based turbulence measurements to quantify mixing in shallow water physical process studies (upwelling regions, fronts. boundary layers) within the context of the LEO-15 based National Ocean Partnership Program (NOPP) coupled ocean
... n observation/modeling system This includes estimating mixing levels, identifying regions of enhanced mixing, determining the horizontal spatial scale of mixing events, defining the role of boundary layers, and parameterizing results for coastal predictive model testing studies of subgrid scale processes. APPROACH My approach is to integrate an optimum turbulence sensor suite into a small, logistically simple, AUV, with input from the ocean turbulence and modeling communities. Then, I seek to establish this small AUV as a viable platform for coastal turbulence research. Towards this end, I obtain horizontals profiles of dissipation rate, temperature microstructure, 3-dimensional small scale velocity, larger scale vertical shear of horizontal current, and stratification in the coastal environment. Subsequently, I studied mixing in the context of the multi-scale measurements surrounding the NOPP LEO-15 node site in the Mid-Atlantic Bight. I sampled adaptively using the Rutgers University continental shelf model SCRUM (Song and Haidvogel, 1994) . The sensors provided data for estimates of eddy diffusivity profile (Gargett and Moum (1995), eddy viscosity profile (using the truncated TKE equation), bulk and gradient Richardson numbers, fluxes [using the correlation technique]. These data enable us to evaluate turbulence closure schemes associated with subgrid mixing processes as parameterized by 3 different surface boundary layer submodels in SCRUM, the coastal circulation model. TRANSITIONS Our AUV sensor technologies, hardware and software, are being considered for inclusion as tactical oceanography payloads for the Manta UUV Initiative, proposed for an upcoming Accelerated Research Initiative (ARI). RELATED PROJECTS 1 My AUV-based turbulence measurement system is also being utilized in NOPP studies with the Harvard led LOOPS project. Measurements were also made in Cape Cod Bay in September 1998.