TITLE:    Palmer LTER: Circulation west of the Antarctic Peninsula
AUTHOR:   EE Hofmann, DA Smith, BL Lipphardt, Jr., RA Locarnini, RC Smith
PAGE:     128 of SCAR SIXTH BIOLOGY SYMPOSIUM, Antarctic Communities: Species,
          Structure and Survival 
ABSTRACT: From 25 March to 15 May 1993, an extensive hydrographic survey was
made of the Palmer Long-Term Ecological Research (LTER) peninsula grid as part
of a multidisciplinary cruise.  The survey covered an area that extended about
900 km alongshore and about 200 km offshore along the western side of the
Antarctic Peninsula.  These measurements provide extensive hydrographic
regional coverage of the area west of the Antarctic Peninsula that extends
from the Bransfield Strait to the Bellingshausen Sea.  Vertical profiles of
temperature and salinity were collected at about 200 stations with a
Sea-Bird CTD system.  For most of the hydrographic casts, observations were
made to within a few meters of the bottom.  At the outer-most stations on the
across-shelf transects, CTD casts were made to the bottom or 3000 m.
Horizontal spacing between the hydrographic stations was 10 km on most
transects; alongshelf spacing between hydrographic transects was 100 km.
These hydrographic observations were used to compute the geostrophic velocity
field for the region west of the Antarctic Peninsula.  The circulation pattern
that emerges from the geostrophic velocity distributions shows a general
clockwise circulation in the region west of the Antarctic Peninsula, with the
Antarctic Circumpolar Current forming the outer portion of this gyre.
Circulation in the inner portion of the LTER grid is characterized by a narrow
southwestward flowing current.  Inshore of this current is a narrow (10-20 km)
northward-flowing current.  It is likely that these inner shelf currents are
important in determining the biological distributions, especially the
distribution of larvae of Antarctic krill.  The velocity distributions also
show a strong current, with surface speeds of 40-50 cm s-1, that extends from
the region west of Bransfield Strait into the Strait proper.  The current may
provide a mechanism for transport of krill larvae from west of the Antarctic
Peninsula into the western and northern regions of Bransfield Strait.