Hydrographic and seismic data analysis in the Norwegian Sea and offshore of the Solomon Islands.

摘要

Seismic oceanography is an important tool in understanding and mapping oceanographic processes because of its ability to map water boundaries, thermohaline intrusions, internal wave strain, and eddies over large lateral distances. The research presented here is split into three separate chapters. First, we present evidence that reflection characteristics on a seismic line in the Norwegian Sea represent various processes occurring in the ocean at the time of acquisition. High amplitude, continuous reflections represent thermohaline intrusions and current shear. Discontinuous, low amplitude reflections represent internal wave strain, and current shear. Coincident with the seismic data was temperature, salinity, and density data recorded at eight locations along the seismic line. This study supports work done by Nandi et al. in 2004 on a seismic line about 20 km north of the line studied here.;The second chapter presents a further analysis of the same seismic line in the Norwegian Sea. Here, the internal wave energy is quantified using horizontal slope spectra. Observed, are correlations between the relative internal wave energy along the seismic line and seafloor roughness as well as critical slopes with respect to the M2 internal tide. This indicates the presence of high-energy internal waves radiating from slopes on the seismic line.;The last study is located offshore of the Solomon Islands in the South Pacific Ocean. Similar strategies as in the Norwegian Sea are applied here on two seismic lines. The analysis of relative internal wave energy, coupled with critical slopes of the bathymetric rises on each line, yield a reflection that matches with the trajectory of the radiating internal tide beam from critical slopes. This confirms similar results found on the Hawaiian Ridge nearby by Martin et al. [in press].;The importance of these analyses is to better understand oceanographic processes occurring in regions of the ocean that relate to heightened mixing and the eventual overturning of water masses. Communication of warm water masses created at the equator with cold water masses created at the poles is not yet fully understood. It is necessary to understand water mass communication because the overturning of water masses maintains the stratification of the oceans, allowing the oceans to sequester carbon dioxide, transport nutrients, and effects atmospheric temperatures.