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生产力最高的区域之一，可能包括一个重要的但下落不明的海洋二氧化碳汇，主要由浮游植物生产驱动。控制这一地区初级生产规模的过程还不是很清楚，但数据表明，铁限制是一个因素。现场观测和模型模拟表明，罗斯海表层水域的四个潜在溶解铁源：(1)从陆架边缘侵入的环极深水；(2)浅岸和近岸地区的沉积物；(3)波利尼亚周围的海冰融化；以及(4)罗斯冰架的冰川融水。主要研究人员假设，通过中尺度流、锋面和涡旋的水动力输送促进了从这四个来源向罗斯海波利尼亚表层水域的溶解铁供应。这些假设将通过现场观测和数值模拟相结合的方式进行检验，并辅之以卫星遥感。现场观测将在南半球夏季长达一个月的巡航中获得。实地数据将被纳入模型模拟，从而能够量化各种假设的铁供应机制的相对贡献，并评估其对初级产量的影响。这项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，这项研究将为预测这一系统在气候变暖时可能发生的变化奠定基础。更广泛的影响包括对研究生和本科生的培训，国际合作，以及与几个正在进行的涉及南大洋科学研究的外联项目的伙伴关系。这项研究还将促进国际研究项目ICED(综合气候和生态系统动力学)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).