New England Seamounts Physical Oceanography: Characterizing Variability at Scales spanning the Mesos
Abstract
The New England Seamounts (NESM) is a region of complex oceanography with processes that span spatial and temporal scales. The physi,cal oceanography here is dominated by the strongly meandering Gulf Stream. This surface-intensified current, which can reach speeds,>4 knots (2 m/s), is a full-water column feature that spans more than 4000-m depth on its approach to the seamount chain. The seamou,nts rise abruptly from the abyssal plain into the path of the oncoming Gulf Stream, resulting in complex current-topography interact,ions as the deep-reaching current navigates past the seamounts. Relatively small changes in Gulf Stream position at the seamounts ca,n have an enormous effect on the environmental conditions relevant for the acoustics, but these position changes are simply not well, resolved by satellite observations nor by typical ocean models. In addition, ocean models that include wind and tidal forcing sugge,st that an internal tide beam emanates from Georges Bank. Models further suggest that this beam passes along the NESM and is refract,ed with some energy ducted against the Gulf Stream towards Cape Hatteras. Superimposed on the tidal-to-mesoscale variability in the,Gulf Stream at the NESM, are long-term global and regional ocean changes that also manifest at the NESM. These long-term changes are, expected to affect acoustics directly by influencing the physical environment and also indirectly by feeding back onto submesoscale, and mesoscale oceanographic processes. The aim of the proposed study is to characterize the oceanographic environment of the water,column by the NESM. This study will increase understanding of processes that drive environmental variability at the NESM to aid in t,he interpretation of acoustic data. Specific objectives are as follows. (1) Determine from existing observations (in situ and remot,ely-sensed) the range of conditions encountered in the vicinity of the Atlantis II Seamount. Develop probability indices for these e,nvironmental conditions based on the time of year, the time-variable position of the Gulf Stream front, and the presence of warm and, cold core rings. Also look for evidence of the internal tide in existing observations. (2) Assess existing oceanographic numerical,model output in this region of complex topography. Consider models with and without tides to determine their fidelity to the observa,tions at the range of scales relevant to the acoustics near the NESM (tidal-to-mesoscale). (3) Collect in situ observations of the i,nternal tide and mesoscale processes with arrays of current- and pressure-sensor equipped inverted echo sounders (CPIESs) to obtain,hourly records of round-trip vertical acoustic travel time, bottom pressure and temperature and near-bottom currents for long durati,on, with the CPIES sites chosen to complement the programs other acoustic and oceanographic measurements. (4) Integrate the results, from (1-3) with acoustic observations and models. These objectives will support the overall goal of investigating underwater acoust,ic propagation, scattering and ambient sound fields at the NESM and will have broad applicability in other regions of complex physic,al oceanography and abrupt topography.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Feb 08, 2022
- Source ID
- N000142212112
Entities
People
- Magdalena Andres
Organizations
- Office of Naval Research
- United States Navy
- Woods Hole Oceanographic Institution