Oceanographic Conditions at the Larsen B Ice Shelf Front Before and After the 2002 Breakout

The Larsen B ice shelf in the Northwest Weddell Sea experienced a catastrophic breakout in early 2002, resulting in an open-water embayment in the region formerly covered by shelf ice, with remnant ice fronts and exposed tidewater glacier regimes. Oceanographic station data occupied at the Larsen B ice front in December 2001 and at the remnant fronts in March 2005 are examined for changes in water mass properties which might be related to the ice shelf breakout of 2002. The region is characterized in both years by a dominance of near-freezing point remnant Winter Water capped by a warmer seasonal mixed layer. At several locations along the ice fronts there is evidence of sub-freezing Ice Shelf Water (ISW) emanating from beneath the ice shelf. In the 2005 observations near the remnant tidewater glacial fronts, some plumes of ISW are marked by significant reductions in optical transmittance, implying that the plumes may be carrying glacial debris. Modified Warm Deep Water (MWDW) is present in only small quantities at some stations, consistent with published observations of conditions at the Larsen C ice shelf front to the south.