Department of Earth and Environmental Sciences, Columbia University in the City of New York, New York City, NY, USA.
Center for Atmosphere Ocean Science, Courant Institute of Mathematical Sciences, New York University, New York City, NY, USA.
Nat Commun. 2020 Feb 28;11(1):1125. doi: 10.1038/s41467-020-14955-0.
The primary productivity of the Southern Ocean ecosystem is limited by iron availability. Away from benthic and aeolian sources, iron reaches phytoplankton primarily when iron-rich subsurface waters enter the euphotic zone. Here, eddy-resolving physical/biogeochemical simulations of a seasonally-forced, open-Southern-Ocean ecosystem reveal that mesoscale and submesoscale isopycnal stirring effects a cross-mixed-layer-base transport of iron that sustains primary productivity. The eddy-driven iron supply and consequently productivity increase with model resolution. We show the eddy flux can be represented by specific well-tuned eddy parametrizations. Since eddy mixing rates are sensitive to wind forcing and large-scale hydrographic changes, these findings suggest a new mechanism for modulating the Southern Ocean biological pump on climate timescales.
南大洋生态系统的初级生产力受到铁供应的限制。远离海底和风沙源，当富含铁的次表层水进入透光区时，铁才会到达浮游植物。在这里，对季节性驱动的南大洋开放生态系统的中尺度和次中尺度物理/生物地球化学模拟表明，等压面搅拌的中尺度和次中尺度效应会将铁进行跨混合层基传输，从而维持初级生产力。与模型分辨率相比，由涡流驱动的铁供应和生产力增加。我们表明，涡流通量可以用经过特殊调整的涡流参数化来表示。由于涡流混合速率对风的强迫和大尺度水文学变化敏感，这些发现表明了一种在气候时间尺度上调节南大洋生物泵的新机制。
