Comments: download pdf
Ref.: Proc. OCEANS MTS/IEEE ' 2007, (ISBN:), p., Vancouver, Canada, 2007. (to appear)
Cold water filaments have important implications in the biological
and chemical exchanges between the coastal and offshore ocean.
The Cape Sao Vicente area in the Southwest coast of Portugal
is a well know region where such phenomena are observed.
Recently, a multidisciplinary project called "Acoustic Tomography Monitoring System" (ATOMS), involving oceanographers and acousticians was conducted in order to characterize the filament structure in the water column. The ATOMS sea trial took place from 22th to 25th October 2004, a season when these phenomena are unlikely. However, satellite images of sea surface temperature (SST) showed the presence of a relatively well formed cold water filament. The SST images where used to limit the area of interest, which is approximately a square box with a side of 100km. A set of 42 CTD casts covering the upper 400m of the water column allowed to find an image of the vertical structure of the cold water filament. Due to weather and technical conditions during the project sea trial, only oceanographic measurements were performed (including currents and chemical water analysis).
Since, the objective of this work, is to evaluate the ability to perform a 3D characterization of vertical structure of the ocean, a minimal transmit-receive acquisition composed of a suspended source from a ship and a drifting vertical array, is assumed. The ship moves around the borders of the interest area emitting acoustic signals at predetermined locations. Thus, the 3D structure of the filament is obtained from a set of 2D inversions. To keep realistic assumptions it is considered that an SST image of the area is available to define the area of interest. Also it is assumed that temperature profiles acquired by some conventional mean are performed at the acoustic array location and at the locations of acoustic signal emissions. The planned sampling strategies and necessary acoustic equipment to resolve such oceanic features is discussed having in mind future sea trials.
ACKNOWLEDGMENT: this work was partially supported by
FCT project ATOMS - POCTI/MAR/15296/1999.
“©1992-2007 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.”