Collaborative Research: Impact of Mesoscale Processes on Iron Supply and Phytoplankton Dynamics in the Ross Sea

罗斯海大陆架是南大洋中最多产的地区之一，可能包含一个重要的，但未被解释的海洋二氧化碳汇，主要由浮游植物的生产驱动。控制该地区初级生产规模的过程尚不清楚，但数据表明，铁限制是一个因素。野外观测和模式模拟表明，罗斯海地表水中溶解铁的四个潜在来源：(1)从陆架边缘侵入的环极深水；(2)浅滩和近岸沉积物；(3)冰湖周边海冰融化；(4)罗斯冰架的冰川融水。主要研究人员假设，通过中尺度洋流、锋面和漩涡的流体动力运输促进了这四个来源的溶解铁向罗斯海冰湖表层水的供应。这些假设将通过现场观测和数值模拟相结合的方式加以检验，并辅以卫星遥感。在南部夏季为期一个月的巡航期间，将获得实地观测。现场数据将纳入模型模拟，从而可以量化各种假设的铁供应机制的相对贡献，并评估它们对初级生产的影响。该研究将为调节铁供应、初级生产和生物地球化学循环的复杂海洋现象提供新的见解和机制理解。因此，这项研究将为预测该系统在气候变暖中可能发生的变化奠定基础。更广泛的影响包括研究生和本科生的培训，国际合作，以及与几个正在进行的关于南大洋科学研究的外展项目的伙伴关系。这项研究也将有助于实现国际研究项目ICED（综合气候与生态系统动力学）和GEOTRACES（海洋环境中的生物地球化学循环和微量元素）的目标。

The Ross Sea continental shelf is one of the most productive areas in the Southern Ocean, and may comprise a significant, but unaccounted for, oceanic CO2 sink, largely driven by phytoplankton production. The processes that control the magnitude of primary production in this region are not well understood, but data suggest that iron limitation is a factor. Field observations and model simulations indicate four potential sources of dissolved iron to surface waters of the Ross Sea: (1) circumpolar deep water intruding from the shelf edge; (2) sediments on shallow banks and nearshore areas; (3) melting sea ice around the perimeter of the polynya; and (4) glacial meltwater from the Ross Ice Shelf. The principal investigators hypothesize that hydrodynamic transport via mesoscale currents, fronts, and eddies facilitate the supply of dissolved iron from these four sources to the surface waters of the Ross Sea polynya. These hypotheses will be tested through a combination of in situ observations and numerical modeling, complemented by satellite remote sensing. In situ observations will be obtained during a month-long cruise in the austral summer. The field data will be incorporated into model simulations, which allow quantification of the relative contributions of the various hypothesized iron supply mechanisms, and assessment of their impact on primary production. The research will provide new insights and a mechanistic understanding of the complex oceanographic phenomena that regulate iron supply, primary production, and biogeochemical cycling. The research will thus form the basis for predictions about how this system may change in a warming climate. The broader impacts include training of graduate and undergraduate students, international collaboration, and partnership with several ongoing outreach programs that address scientific research in the Southern Ocean. The research also will contribute to the goals of the international research programs ICED (Integrated Climate and Ecosystem Dynamics) and GEOTRACES (Biogeochemical cycling and trace elements in the marine environment).