Circulation and Seasonal Evolution of Polar Waters . . .

• Main Authors: Tom Trull, Stephen R. Rintoul, Edward R. Abraham
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2001
• Subjects: Antarctic; Southern Ocean; The Antarctic; Antarc*; Sea ice
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.19.4783; http://www.mcs.vuw.ac.nz/~abraham/Publications/SOIREE_settings.pdf

The Southern Ocean Iron Release Experiment (SOIREE)was carried out in late summer (February 1999) south of Australia (613S, 1403E . Thisreg)b of the southern Antarctic Zone (AZ-S , between the southern branch of the Polar Front (PF and the southern front of the Antarctic Circumpolar Current (SAACF , is characterized by weak currents and is remote from the in#uence of sea-ice or coastal waters. The SOIREE site exhibitshig nutrient concentrations year-round (phosphate, nitrate and silicate remain above 10 #M), low chlorophyll accumulations ((0.5#gbbH and moderate summer mixed-layer depths (50}70 m). The SOIREE iron fertilization led to alarg increase inalgP biomass, particularlylarg diatoms, and persisted into March well after normal seasonal production is complete. No increase in carbon export occurredduring the SOIREE 13-day observation period. The seasonal cycles of mixed-layer development and low biomass accumulation at the SOIREE site are representative of most of theregFb between the PF and the SACCF, i.e. between &54 and &623S, and to a lesser extent the Polar Frontal Zone. However, north of &593S surface waters are depleted in silica by mid-summer (as occurs year-round north of the Subantarctic Front). Adi!erent response to iron fertilization is likely under these conditions, possibly the promotion ofligP/5 silici"ed diatoms and non-siliceousorgsilice whose ability to export carbon is uncertain. The SOIREE fertilized waters are likely to have remained at the surface in the AZ-SthrougHb) the winter.