| Sept. 18,1998 |
The submarine USS Hawkbill (SSN 666) returned to Pearl Harbor
from Submarine Science Ice Expedition '98 (SCICEX) Tuesday, September 15th. The submarine
departed Pearl Harbor three months ago heading north to the Arctic Ocean with a team of
two Navy and five civilian scientists. Carrying special equipment, the attack submarine
became a mobile research station collecting data on water temperature, mapping the ocean
bottom and measuring ice thickness. Since 1993 the US Navy has made a Sturgeon-class
nuclear powered attack submarine available for annual unclassified science cruises to the
Arctic Ocean. These cruises have collected water samples and CTD casts from surface
stations as well as collecting underway oceanographic and geophysical data across the
entire deep Arctic Ocean. |
The Seafloor Characterization and Mapping Pods (SCAMP) was installed for the
first time on the USS Hawkbill for SCICEX-98. Sub-bottom profiler data was
collected with the High-Resolution Sub-bottom Profiler, an adapted Bathy-2000P from Ocean
Data Equipment Corporation bought with funds from the Palisades Geophysical Institute.
Gravity data was collected with a Bell BGM-3 underway marine gravimeter on loan from
NAVOCEANO. Underway swath bathymetry and backscatter were collected from the Sidescan
Swath Bathymetric Sonar (SSBS), a SeaMARC-type instrument. These underway data were
collected along approximately 17,000 km of track in the Arctic Ocean operational area
defined by the Navy for SCICEX. |
The
Bell BGM-3 gravimeter and the Ocean Data Equipment Corporation Bathy-2000P
both performed exceptionally well, operating continuously throughout the science program.
The Bathy-2000P appears to have benefitted from the low-noise
environment of the submarine. In some areas the sub-bottom profiler records
extend to as much as 200 meters, well beyond the expected 100 meter penetration. |
The
SSBS suffered from some problems, but on the whole performed well for a first deployment.
The SSBS operated during about 95% of the time in the science area, but suffered from a
weaker returned signal on the starboard side arrays. Useful data were recovered from both
arrays. We will understand the extent of the useful data once processing is underway.
Preparations to improve the SSBS for SCICEX-99 are underway. |
While
underway data was collected during the entire science program, the geophysics project was
focused on the Gakkel Ridge, the slowest spreading ridge in the world ocean. Swath data
were collected during SCICEX-98 to fill in the gaps between the "patch" surveys
done in 1996 from the USS Pogy. Thirty new crossings of the ridge axis were arranged to
collect continuous bathymetry and backscatter along the sampled sections of the ridge
axis. Approximately 3300 km of data were collected over the Gakkel Ridge axis.
These data reinforce the image developed from the earlier data set of a deep axial valley
(~5000 meters), with high relief flanks (~1000 meters). The deepest point observed
was 5,173 meters. The shallowest point observed during this survey was about 600
meters. Two figures detailing high resolution sub bottom stratigraphy of the Gakkel
Ridge area follow. In many cases, the data records detail sediment reflectors of
less than 10cm thickness. |
Figure 1: Bathy-2000P sub bottom data
image using Bathy-2000W Processing software
Figure 2: Bathy-2000P sub bottom data
image using Bathy-2000W Processing software
Additional information on the SCICEX project is available on the
following WWW sites:
http://www.csp.navy.mil/scicex/index.htm USS HAWKBILL (SSN 666) -
SCICEX 99
Add this link to your favorites and visit often. With the assistance of the
Scientists involved, Jeff Gossett, Barry Campbell and the crew of the USS HAWKBILL, we
will keep you up to date on SCICEX 99.
http://www.ldeo.columbia.edu/SCICEX SCICEX
(Scientific Ice Expeditions) Unclassified use of US Navy submarines in the Arctic
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