Accession Number:

ADA158640

Title:

Airborne Electromagnetic Bathymetry

Descriptive Note:

Final rept.

Corporate Author:

NAVAL OCEAN RESEARCH AND DEVELOPMENT ACTIVITY STENNIS SPACE CENTER MS

Personal Author(s):

Report Date:

1985-04-01

Pagination or Media Count:

23.0

Abstract:

An experimental airborne electromagnetic AEM survey was carried out in the Cape Cod Bay area to investigate the potential of extracting bathymetric information for a shallow ocean. A commercially available Dighem III AEM system was used for the survey without any significant modification. The helicopter- borne system operated at 385 Hz and 7200 Hz, both in a horizontal coplanar configuration. A concurrent ground truth survey included extensive acoustic soundings, as well as spot water conductivity measurements. Because of a lack of knowledge about the absolute system calibration figures, an acoustic-sounding calibration was made for each flight line using a small portion of AEM data to derive the zero-level signal, amplitude, and phase calibration factors for each coil pair. The interpreted bathymetric profiles show excellent agreement with corresponding acoustic depth profiles up to one possibly more skin depth of the source frequency. It is envisioned that with further improvements in hardware and software, the bathymetric resolution may extend beyond the skin depth. AEM data can also produce as by-products conductivity profiles of both seawater and bottom sediments that may find potential applications in mine warfare and offshore geotechnical engineering works.

Subject Categories:

  • Physical and Dynamic Oceanography

Distribution Statement:

APPROVED FOR PUBLIC RELEASE