From the InterRidge News
 Arctic Geophysical Data Acquisition from US Navy Submarines
                          an update
                              
     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. Approximately 30,000 km (approximately 20,000
km more should be collected during the cruise of the USS
Pogy, which is presently underway) of underway gravity
anomaly and narrow beam bottom sounder data have
substantially expanded the unclassified data base for the
Arctic Ocean. Three more cruises in 1997, 1998 and 1999 will
complete the planned SCICEX program.

     It has been widely recognized that the stability,
silence, range and independence from surface conditions
render a Sturgeon-class submarine a nearly ideal platform
for geophysical measurements. Floating pack ice, which
covers most of the Arctic Ocean, restricts or prohibits
access to much of the basin. The submarine's independence
from surface ice is a particular advantage in the Arctic
permitting the first ever systematic bathymetric surveys in
the basin.

     While the "silent service" has traditionally abhorred
active sonars, the Navy has responded to the enthusiasm of
the scientific community for additional data from the once-
in-a-lifetime opportunity of unrestricted access to the deep
Arctic Ocean. Additional instrumentation for future cruises
requires funds for study, acquisition, testing and
implementation. NSF's Office of Polar Programs supported an
initial engineering study last year and has agreed to fund
the fabrication and testing of a SeaMARCĒ-type Sidescan
Swath Bathymetric Sonar and a Data Acquisition and Quality
Control System. In support of NSF's commitment, a private
organization, the Palisades Geophysical Institute, is
funding acquisition of a chirp, swept-frequency sub-bottom
profiler. The transducers for these sonars will be mounted
in a instrument "pod" attached to the keel of the submarine.
This equipment should be ready for the next SCICEX cruise,
which is scheduled to get underway in late July or early
August of 1997

     If all goes according to plan, the SCICEX program will
collect co-registered backscatter, bathymetry, chirp sub-
bottom profiler and gravity anomaly data during the
remaining unclassified Arctic cruises. If previous cruises
are an indication of what we can expect in the future, the
next three cruises in this program will collect
approximately 60,000 km of additional underway data and
approximately 1,000,000 km2 of swath imagery by the end of
the 1999 trip.

     Four organizations are collaborating to make these
plans a reality. Lamont-Doherty Earth Observatory (LDEO) is
acting as lead institution, managing acquisition,
integration and testing of the instruments and computer data
logging system. Alliant Techsystems of Mukilteo, Washington
has been contracted to fabricate the Arctic-optimized
SeaMARCĒ-type side-looking sonar. The Hawai'i Mapping
Research Group (HMRG) will adapt their software for the MR-1
towed side-looking sonar for the submarine application. The
Arctic Submarine Lab (ASL) of San Diego, California is
developing a design for the transducer "pod" that will be
mounted on the submarine keel and preparing the engineering
documentation required by the Navy for this installation.
Once completed, LDEO will act as caretaker for the
instrumentation, maintaining, repairing and improving it as
necessary or desirable. ASL will be responsible for the
annual installation and demobilization of the instruments.
LDEO and HMRG will operate the system, archive and reduce
the data to a consistent standard over the three year life
of the program in support of PI's funded under the SCICEX
program and for the community at large.

     Questions about this instrumentation; known
collectively as SCAMP (Seafloor Characterization and Mapping
Package) can be directed to Bernard Coakley at LDEO
(bjc@ldeo.columbia.edu or (914) 365-8552) Questions about
the SCICEX program and future cruises can be directed to
either Odile de la Beaujardiere at the Office of Polar
Programs at NSF (odelab@nsf.gov or (703) 306-1033) or Mike
Van Woert at the Office of Naval Research ((703) 696-4720).