High-resolution Bathymetry of the Alaska Margin Derived from SCICEX/SCAMP Data

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Intellectual Merit: The goal of this Small Grant for Exploratory Research (SGER) is to prouce high-resolution bathymetric maps of the Alaska margin using acoustic data collected during the 1999 SCience ICe EXercise (SCICEX) to determine whether large ice sheets known to have eroded shallow features in the Amerasian Basin of the Arctic Ocean derived from glaciers adjacent to the Canadian Arctic Archipelago. Recently discovered evidence of glacigenic flutes on the Alaska margin supports the hypothesis that thick ice sheets originated in the Canadian Arctic Archipelago, eroding submarine environs to depths of ~700 m during the Pleistocene. To demonstrate unequivocally where these ice sheets originated, it is necessary to compare high-resolution bathymetry data with the lineations already discovered in SCICEX sidescan data and document the depth of occurrence and scale of features as a function of distance from the proposed source region. The bathymetry data collected for the Alaska margin during SCICEX-99 have not been processed due to inaccuracies caused by the vertical motion of the submarine through the water column as these data were acquired. This effort will modify existing software that presently assumes near-constant water properties at the sonar transducers to generate bathymetric tables for a platform that is moving through a changing water column. The resultant bathymetric dataset will be available to help oceanographers studying SCICEX data along the Alaska margin evaluate how the length scales of topographic features relate to the observed changes in physical and chemical water properties. Broader Impacts: This project will serve as a doctoral thesis for Jennifer Engels, a graduate student at the University of Hawaii. She has presented her discovery of the glacigenic features in SCICEX sidescan data for the Alaska margin at both the AGU/EGS meeting in Nice, France and the INQUA meeting in Reno, Nevada, and is completing a manuscript describing this discovery for submission to the Journal of Geology. By examining the bathymetric data, which will essentially extend this glacigenic story into the third dimension, Engels will document the source of the large Amerasian ice sheets and lay the foundation for dating sediment cores in the region. This study should be advantageous for future AUV operations in the Arctic Ocean, where vehicles will likely move through both vertical and horizontal changes in the water column as they collect acoustic data.