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Unmanned Underwater Vehicle (UUV) simulations that include environmental impacts to vehicle performance can increase mission success rates and decrease risk for the vehicle operator. In this thesis, a UUV power model and hydrodynamic model are combined in a simulation environment to create a framework for predicting vehicle performance in high currents. Field data from fixed sensors and UUV missions are used to validate the models used in the simulation tool. Results of the simulation tool are used to predict vehicle failure events, to study vehicle performance metrics, and are translated into a Tactical Decision Aid (TDA). The TDA is a powerful tool to mitigate risk in the pre-mission planning process. Two case studies in the Mission Bay, CA region are presented to demonstrate the utility of the TDA.

Author Posting. © American Meteorological Society, 2022. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 52(10), (2022): 2325–2341, https://doi.org/10.1175/jpo-d-21-0015.1., The ocean surface boundary layer is a gateway of energy transfer into the ocean. Wind-driven shear and meteorologically forced convection inject turbulent kinetic energy into the surface boundary layer, mixing the upper ocean and transforming its density structure. In the absence of direct observations or the capability to resolve subgrid-scale 3D turbulence in operational ocean models, the oceanography community relies on surface boundary layer similarity scalings (BLS) of shear and convective turbulence to represent this mixing. Despite their importance, near-surface mixing processes (and ubiquitous BLS representations of these processes) have been undersampled in high-energy forcing regimes such as the Southern Ocean. With the maturing of autonomous sampling platforms, there is now an opportunity to collect high-resolution spatial and temporal measurements in the full range of forcing conditions. Here, we characterize near-surface turbulence under strong wind forcing using the first long-duration glider microstructure survey of the Southern Ocean. We leverage these data to show that the measured turbulence is significantly higher than standard shear-convective BLS in the shallower parts of the surface boundary layer and lower than standard shear-convective BLS in the deeper parts of the surface boundary layer; the latter of which is not easily explained by present wave-effect literature. Consistent with the CBLAST (Coupled Boundary Layers and Air Sea Transfer) low winds experiment, this bias has the largest magnitude and spread in the shallowest 10% of the actively mixing layer under low-wind and breaking wave conditions, when relatively low levels of turbulent kinetic energy (TKE) in surface regime are easily biased by wave events., This paper is VIMS Contribution 4103. Computational resources were provided by the VIMS Ocean-Atmosphere and Climate Change Research Fund. AUSSOM was supported by the OCE Division of the National Science Foundation (1558639).

The inner shelf, the transition zone between the surfzone and the midshelf, is a dynamically complex region with the evolution of circulation and stratification driven by multiple physical processes. Cross-shelf exchange through the inner shelf has important implications for coastal water quality, ecological connectivity, and lateral movement of sediment and heat. The Inner-Shelf Dynamics Experiment (ISDE) was an intensive, coordinated, multi-institution field experiment from September–October 2017, conducted from the midshelf, through the inner shelf, and into the surfzone near Point Sal, California. Satellite, airborne, shore- and ship-based remote sensing, in-water moorings and ship-based sampling, and numerical ocean circulation models forced by winds, waves, and tides were used to investigate the dynamics governing the circulation and transport in the inner shelf and the role of coastline variability on regional circulation dynamics. Here, the following physical processes are highlighted: internal wave dynamics from the midshelf to the inner shelf; flow separation and eddy shedding off Point Sal; offshore ejection of surfzone waters from rip currents; and wind-driven subtidal circulation dynamics. The extensive dataset from ISDE allows for unprecedented investigations into the role of physical processes in creating spatial heterogeneity, and nonlinear interactions between various inner-shelf physical processes. Overall, the highly spatially and temporally resolved oceanographic measurements and numerical simulations of ISDE provide a central framework for studies exploring this complex and fascinating region of the ocean.

Sea ice inhibits the development of wind‐generated surface gravity waves which are the dominant factor in upper ocean mixing and air‐sea fluxes. In turn, sea ice properties are modified by wave action. Understanding the interaction of ice and waves is important for characterizing both air‐sea interactions and sea ice dynamics. Current leading theory attributes wave attenuation primarily to scattering by ice floes. Here we use new in situ wave measurements to show that attenuation is dominated by dissipation with negligible effect by scattering. Time series of wave height in ice exhibit an ``on/off" behavior that is consistent with switching between two states of sea ice; a relatively unbroken state associated with strong damping (off), possibly caused by ice flexure, and very weak attenuation (on) across sea ice that has been broken up by wave action. Plain Language Summary Waves created by wind at the ocean surface are strongly attenuated when they travel across ice‐covered regions. Until now, this effect was thought to be the result of waves reflection off pieces of ice. Using new measurements of wave directions, we show that waves do not come for a broad range of directions, and scattering must be weak. Instead we find that attenuation is highly variable and related to the size of ice floes. We hypothesize that attenuation may be caused by cyclic deformation of the ice. When the waves are large enough to break the ice up, this deformation stops and the attenuation is much less. This finding is important for forecasting waves in ice‐infested waters as well as predicting seasonal sea ice extent.

© The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Andres, M., Siegelman, M., Hormann, V., Musgrave, R. C., Merrifield, S. T., Rudnick, D. L., Merrifield, M. A., Alford, M. H., Voet, G., Wijesekera, H. W., MacKinnon, J. A., Centurioni, L., Nash, J. D., & Terrill, E. J. Eddies, topography, and the abyssal flow by the Kyushu-Palau Ridge near Velasco Reef. Oceanography, 32(4), (2019): 46-55, doi: 10.5670/oceanog.2019.410., Palau, an island group in the tropical western North Pacific at the southern end of Kyushu-Palau Ridge, sits near the boundary between the westward-​flowing North Equatorial Current (NEC) and the eastward-flowing North Equatorial Countercurrent. Combining remote-sensing observations of the sea surface with an unprecedented in situ set of subsurface measurements, we examine the flow near Palau with a particular focus on the abyssal circulation and on the deep expression of mesoscale eddies in the region. We find that the deep currents time-averaged over 10 months are generally very weak north of Palau and not aligned with the NEC in the upper ocean. This weak abyssal flow is punctuated by the passing of mesoscale eddies, evident as sea surface height anomalies, that disrupt the mean flow from the surface to the seafloor. Eddy influence is observed to depths exceeding 4,200 m. These deep-​reaching mesoscale eddies typically propagate westward past Palau, and as they do, any associated deep flows must contend with the topography of the Kyushu-Palau Ridge. This interaction leads to vertical structure far below the main thermocline. Observations examined here for one particularly strong and well-sampled eddy suggest that the flow was equivalent barotropic in the far field east and west of the ridge, with a more complicated vertical structure in the immediate vicinity of the ridge by the tip of Velasco Reef., We gratefully acknowledge the help of Captain David Murline and the crew of R/V Roger Revelle and the shore-based assistance of Lori Colin and Pat Colin of the Coral Reef Research Foundation. We sincerely thank Terri Paluszkiewicz for her steadfast support of basic research programs, including FLEAT, during her many years of service to the community as Office of Naval Research (ONR) Physical Oceanography Program Manager. MA was supported by ONR grant N000141612668, MS and MAM by N00014-16-1-2671, MHA and JAM by N00014-15-1-2264 and N00014-16-1-3070, GV by N00014-15-1-2592, DLR by N00014- 15-1-2488, and STM and EJT by N00014-15-1-2304. VH and LC were supported by ONR grant N00014-15-1-2286 and NOAA GDP grant NA15OAR4320071. RCM was supported by the Postdoctoral Scholar Program at the Wood Hole Oceanographic Institution, with funding provided by the Weston Howland Jr. Postdoctoral Scholarship. We thank the Palau National Government for permission to carry out the research in Palau.

© The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in St. Laurent, L., Ijichi, T., Merrifield, S. T., Shapiro, J., & Simmons, H. L. Turbulence and vorticity in the Wake of Palau. Oceanography, 32(4), (2019): 102-109, doi: 10.5670/oceanog.2019.416., The interaction of flow with steep island and ridge topography at the Palau island chain leads to rich vorticity fields that generate a cascade of motions. The energy transfer to small scales removes energy from the large-scale mean flow of the equatorial current systems and feeds energy to the fine and microstructure scales where instability mechanisms lead to turbulence and dissipation. Until now, direct assessments of the turbulence associated with island wakes have received only minimal attention. Here, we examine data collected from an ocean glider equipped with microstructure sensors that flew in the island wake of Palau. We use a combination of submesoscale modeling and direct observation to quantify the relationship between vorticity and turbulence levels. We find that direct wind-driven mixing only accounts for about 10% of the observed turbulence levels, suggesting that most of the energy for mixing is extracted from the shear associated with the vorticity field in the island’s wake. Below the surface layer, enhanced turbulence correlates with the phase and magnitude of the relative vorticity and strain levels of the mesoscale flow., We thank the Palau National Government for permission to carry out the research in Palau. We also thank the US Office of Naval Research for supporting this work. We especially thank Pat and Lori Colin of the Coral Reef Research Foundation and their team for accommodating our research team in Koror, Palau, and running vessel operations in support of glider deployments and recoveries. Sean Whelan of the Woods Hole Oceanographic Institution and Lance Braasch of Scripps Institution of Oceanography provided technical support in the field. Funding for the development of HYCOM has been provided by the National Ocean Partnership Program and the Office of Naval Research. Data assimilative products using HYCOM are funded by the US Navy. Computer time was made available by the Department of Defense High Performance Computing Modernization Program. The output is publicly available at https://www.hycom.org/.