Klinck¹, John M., Michael S. Dinniman¹, Walker O. Smith, Jr.² and Eileen E. Hofmann¹

¹Center for Coastal Physical Oceanography, Old Dominion University, Crittenton Hall, Norfolk, VA 23529, Tel: 757-683-6005, Fax: 757-683-5550, E-mail: klinck@ccpo.odu.edu and ²Virginia Institute of Marine Science, College of William and Mary

Biogeochemical climatologies for the Ross Sea, Antarctica: Temporal patterns of primary production

The temporal pattern of nutrient (nitrate and silicic acid) and chlorophyll distributions in the Ross Sea is formulated by two independent ways. The first procedure compiles all available data from known cruises from 1970 to the present and generates a three-dimensional grid for the months from November through February using the iterative difference-correction scheme. The second method uses a three-dimensional circulation model that includes the effects of the Ross Sea gyre off the continental shelf, and investigates the effects of currents and phytoplankton uptake on nutrient distributions and phytoplankton standing stocks. The two approaches produced similar results, although the circulation model produced distributions that were more variable in space due to its finer resolution. The nutrient distributions were characterized by elevated concentrations in early spring and gradual reductions to ca. 15 and 40 M (nitrate and silicic acid, respectively) in summer. Nutrient depletion did not occur despite the favorable growth conditions in summer, suggesting that an alternative limitation occurs. Modeled chlorophyll concentrations reached ca. 5 g/L in December and declined thereafter, similar to the observed in situ seasonal declines. Seasonal primary production calculated from the nitrate deficits and the circulation model suggested that production was ca. 120 g C/sq m, similar to other estimates using independent methods. Both the nutrient/pigment climatologies and circulation model results confirm that the Ross Sea continental shelf is among the most productive regimes of the entire Southern Ocean.