Observations and modeling of the coastal ocean beneath tropical and extra-tropical cyclones

Tropical and extra-tropical cyclones are important episodic events that redistribute heat, nutrients, sediment, pollutants, carbon and other tracers on continental shelves, enhance near-surface chlorophyll and initiate phytoplankton blooms. These storms also cause extensive coastal damage through direct wind forcing, storm surge and precipitation. Despite the importance of these storms, they are chronically difficult to sample due to the extreme sampling conditions. In my thesis I present data from Teledyne-Webb Slocum autonomous underwater vehicles (AUVs) deployed beneath an extra-tropical cyclone, Nor’Ida, and Huricane Sandy on the Mid-Atlantic Bight (MAB). In the first chapter of my thesis I used data from multiple AUVs and an ocean observation network to show that small-scale (O10km) spatial variability in sediment grain size is responsible for observed spatial variability in sediment resuspension and transport, even in large storms. In the second chapter we deployed an AUV with an upward looking current meter beneath Hurricane Sandy and found that offshore advection of a downwelling front rapidly removed a cold water mass (the summer Cold Pool) from the continental-shelf over 18 hours before the storm made landfall. This study demonstrates that advective processes need to be included in future coupled atmospheric-ocean models to accurately forecast storm intensity. In the third and final chapter of my thesis I used optical, acoustic and hydrographic data collected by the AUV during Hurricane Sandy to validate coupled hydrographic, bottom boundary layer and sediment models. This study is one of the first validations of the coupled model during an extreme storm on the MAB and shows broad patterns of erosion and deposition during Hurricane Sandy.Ph. D.Includes bibliographical referencesby Travis N. Mile