Jefferson
Keith
Moore, University of California, Irvine, jkmoore@uci.edu
(Presenting)
Shanlin
Wang, University of California, Irvine, shanlinw@uci.edu
Aparna
Krishnamurthy, University of California, Irvine, aparnak@uci.edu
We are pursuing several lines of research to improve our ability to model ecosystem dynamics and carbon cycling in the Southern Ocean with the Biogeochemical Elemental Cycling (BEC) model. The BEC ocean model includes several functional groups of phytoplankton (diatoms, diazotrophs, picophytoplankton, and coccolithophores) and multiple potentially growth-limiting nutrients (nitrate, ammonium, phosphate, silicic acid, and iron). Ongoing efforts seek to optimize parameter values for the Southern Ocean region through evaluation of model output with observed chlorophyll and nutrient distributions. We are also adding an explicit Phaeocystis functional group to the model. Phaeocystis antarctica is sometimes the dominant component of the phytoplankton community during blooms in this region, mediated through a competition with diatom species. A number of factors have been proposed to influence the competition between Phaeocystis and diatoms including differential light harvesting capacity, different iron requirements and uptake capabilities, and differential grazing and sinking mortality terms. The model can serve as a tool to investigate these hypotheses. We are also examining the roles of iron inputs from the atmosphere and the sediments in driving Southern Ocean biogeochemistry. Sedimentary sources are critical in driving observed phytoplankton blooms near key Southern Ocean islands. Accounting for spatial and temporal variability in the solubility of aerosol iron can substantially impact deposition of soluble iron from the atmosphere.
NASA Carbon Cycle & Ecosystems Active Awards Represented by this Poster: