Sound scattering by marine organisms was studied off the Oregon coast and between Hawaii and Adak, Alaska. Variations in scattering were observed over a period of several hours, over did (24-hour) periods, from month to month, from inshore to offshore, in relation to biomass of midwater animals, and temperature and salinity. Usually one or two scattering layers migrated vertically, ascending or descending at dusk and dawn respectively. At times reflectors migrated between surface waters and upper scattering layers during twilight periods. No statistical difference was found between rates of ascent and descent because of the variability in rates of migration that was observed. The amount or thickness of scattering in the water column was found to vary from day to night and with seasons. There was a general trend for more scattering during night than day, yet it was not statistically significant. Seasonally, more scattering appeared to be present during the summer in some years but not in others. Surface scattering varied not in amount but in the type present during different seasons and between day and night. Geographically, scattering was found in smaller amounts in offshore than inshore waters of Oregon. Variations in scattering were noted among the water masses between Hawaii and Adak, Alaska. Geographic changes in scattering and biomass showed a positive correlation between euphausiid catches and the amount of scattering. However, euphausiids are not considered the only group scattering sound. The great amount of variability in scattering is discussed. It may be due to differences in the species causing scattering and variability in the behavior of individual species, possibly resulting from changes in light and temperature. / Graduation date: 1968

Thesis (M.S.)--University of Wisconsin--Madison. / Typescript. Includes bibliographical references (leaves 77-78).

Thesis (M.S.)--University of Wisconsin--Madison. / Typescript. Title from title screen (viewed Sept. 24, 2007). Includes bibliographical references (leaves 77-78). Online version of the print original.

No description available.

A high-resolution radio echo sounder operating at a frequency of 840 MHz has been developed for sounding of small and medium-sized polar glaciers and ice caps. The sounder uses a compact, high-gain antenna which improves the system performance, suppresses valley wall echoes and simplifies operation from light aircraft. Successful field trials were carried out on the Rusty, Trapridge and Hazard Glaciers, Yukon Territory, Canada. Results of airborne surveys compare well with ice depths obtained from earlier ground-based soundings on the Rusty and Trapridge Glaciers. The maximum ice thickness encountered was 200 m on Hazard Glacier. Owing to the high operating frequency, random scattering from inhomogeneities within the ice is a major cause of signal degradation. For this reason the sounder cannot penetrate great thicknesses of temperate or debris-rich ice. Spatial averaging, an immediate result of operating from a moving platform, reduces the effects of back-scattered "clutter. " Results of ground-based tests on the Hazard Glacier yield a value for ftan 8 = 0.26 at -50C, in agreement with predicted values. The total received power and the echo details have both been found to be very sensitive to small (<<I0 cm) changes in antennae position. Large fluctuations in power, caused by roughness at or near the ice/air surface, prevented using single coverage data to detect birefringence in glacier ice. The results also indicate that the standard photographic records should be replaced by a recording medium capable of storing more precise and accessible data. A storage medium such as magnetic tape should not degrade the radar data, and would at the same time relieve a data processing burden. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

Thesis (M.Eng.)--Memorial University of Newfoundland, 2003. / Includes bibliographical references.

A primary goal of this thesis has been to demonstrate that stable, useful measurements of the orientation of the acoustic signal vector as a function of range and time can be obtained from ocean backscatter, and that this orientation, or acoustic phase, can be related to the local sound speed distribution. Such a measurement is quite distinct from the related problem of detecting the rate of phase change, which forms the basis of Doppler technology. Doppler measurements can be made using echoes from a single point, or a sparsely distributed set of targets. Consistent and useful measurement of absolute phase, is inherently more difficult, since it depends upon the positions of individual scatterers, which are normally random and sparse relative to the acoustic wavelength. / Graduate

Thesis (Ph. D.)--University of Wisconsin--Madison, 1967. / Typescript. Vita. "Diel activity and vertical distribution of yellow perch ... under the ice," by Gary L. Hergenrader and Arthur D. Hasler inserted between leaves 15 and 16. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Washington, 2000. / Vita. Includes bibliographical references.

Thesis (Ph.D.) - University of St Andrews, September 2008. / Electronic version restricted until 16th September 2009.