My research focuses on understanding the mixing and transport processes driving the water mass transformation in the estuarine and coastal regions as these processes ultimately control the fate of freshwater and the water mass structure on the continental shelf. To advance this pursuit I develop novel analytical tools and utilize numerical models along with observational oceanographic and meteorological data in an attempt to capture and advance the understanding of the underlying physical processes.
Dramatic transformations occur as water masses transition from fresh riverine water to open ocean composition. Turbulent mixing processes are responsible for the bulk of the mixing required for this transformation, which occurs within the estuary and the buoyant river plume that is discharged into the coastal ocean. These are dynamic regions with an inherently high degree of spatial and temporal variability which has led to important aspects of the mixing and transport processes remaining elusive.
My current work focuses on the turbulent mixing processes in the tidal plume of the Columbia River. The large scale far-field structure of a river plume and its response to various external forcing variables has typically been considered sub-tidal phenomenon generally disconnected from estuarine processes. However, within a tidal excursion of the mouth of the estuary the tidal river plume is essentially an extension of the estuary into the coastal ocean. Recently it has become apparent that tidally driven processes in this region can potentially set-up the structure of the far-field plume; however, the dominant mixing processes/regions are still not well understood.
My previous work has focused on the large scale response of buoyant river plume systems to wind forcing. Specifically, I examined the role of cross-chore winds and shelf circulation on the structure of the Hudson River plume and the freshwater transport pathways in the Mid-Atlantic Bight (MAB). Using the Regional Ocean Modeling System (ROMS) I created idealized and realistic model domains with idealized and realistic forcing parameters to examine the underlying physical response to the cross-shore winds that are regularly observed on the New Jersey coast in the winter. The numerical results combined with observational data analysis have led to the development of a new theory on the response of buoyant plumes to cross-shore winds and a new understanding of the factors controlling the dominant freshwater transport pathways in the MAB. The structure and offshore position of a plume subjected to offshore directed winds was found to reach a relative steady state dependent on the structure and strength of the estuarine forcing and ambient shelf circulation.
Going forward I hope to continue to examine the processes controlling the structure, transport, and turbulent mixing in gravity currents and stratified estuary/coastal flows in an effort to advance the understanding of the processes coupling the estuary and coastal ocean and the factors controlling the water mass transformation and freshwater transport pathways on the continental shelf. More specific areas of interest involve addressing the existing gap in our knowledge on how tidally driven processes near the mouth of estuaries impact the structure and circulation in the coastal ocean and the estuaries themselves. Also, important details on the role of lateral spreading, rotation, ambient water mass structure on mixing and frontal propagation of tidally forced plume systems are still not adequately understood.