Iron sources, horizontal and vertical transport and biological responses in the Southern Scotia Sea Meng Zhou and Blue Water Zone Group
Department of Environment, Earth and Ocean Sciences
University of Massachusetts Boston
The rapid transition from a low to a high productive water in the southern Drake Passage has been studied in both field cruises and numerical modeling. The surface drifters and Acoustic Doppler Current Profiler (ADCP) measurements indicate that a branch of the Antarctic Circumpolar Current (ACC) is topographically steered into the Schackleton Gap between Schackleton Transverse Ridge and Elephant Island, interacts with shelf waters around Elephant Island and leads to a massive offshelf transport of iron rich shelf waters. The analysis of water types and Ra isotope measurements shows the similar results of offshelf transport of shelf waters and mixing between ACC and shelf waters in the southern Drake Passage and southern Scotia Sea. Iron-addition experiments demonstrate the iron deficit in the ACC surface water, and responses of plankton communities to iron addition. To find the source waters, the results from a winter cruise show the consistent patterns of circulation and offshelf transport of iron rich shelf waters in different seasons around Western Antarctica Peninsula. Both trace metal measurements and modeling results indicate the sources of iron from the shelves of Southern Shetland and Elephant Islands. The modeling studies also focus on horizontal transport, vertical mixing and recycling of iron that determine the longevity of iron fertilization in the iron plume.
