UC Santa Cruz

The Amundsen Sea Polynya International Research Expedition (ASPIRE) (Dec 2010 - Jan 2011) investigated high latitude (71-75S, 110-120W) ocean dynamics to better understand the polynya's high biological production. Hydrographic and dFe data from Conductivity-Temperature-Depth (CTD) measurements highlight a melt-laden outflow emanating from the Dotson Ice Shelf (DIS) and flowing between 400-600 m throughout the Dotson trough. Observations in the polynya near icebergs show water mass mixing of meltwater and Circumpolar Deep Water and elevated concentrations of dFe, indicating that drifting icebergs could deliver iron into the mixed layer either from in situ melt or by mixing up melt-laden outflow waters from the DIS. Time series data at the DIS outflow indicate warming since 2007. Although nearby Pine Island Glacier (PIG) outflow is overall warmer and saltier than DIS outflow, calculated meltwater fractions show similar relative quantities of meltwater from both PIG and DIS.