Importance of Ekman transport and gyre circulation change on seasonal variation of surface dissolved iron in the western subarctic North Pacific
Importance of Ekman transport and gyre circulation change on seasonal variation of surface dissolved iron in the western subarctic North Pacific
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埃克曼输运和环流变化对北太平洋西亚北极表面溶解铁季节变化的重要性
DOI：
10.1002/2016jc012354
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发表时间：
2017
影响因子：
--
通讯作者：
Wakatsuchi Masaaki
中科院分区：
文献类型：
--
作者：
Nakanowatari Takuya;Nakamura Tomohiro;Uchimoto Keisuke;Nishioka Jun;Mitsudera Humio;Wakatsuchi Masaaki
铁（Fe）是海洋浮游植物必需的营养元素，也是海洋碳循环的重要元素。本研究探讨了控制溶解铁（dFe）的季节变化的机制，在西亚北极北太平洋（WSNP），使用海洋环流模式耦合一个简单的地球化学模式，包括dFe循环喂养的两个主要来源（大气尘埃和大陆架沉积物）。该模型再现了观测浓度的dFe和常量营养素在Oyashio地区的表面在冬季（2月至3月）和夏季（7月至9月）的最小值的季节性周期，虽然模拟的季节性振幅的一半观测值。对混合层dFe收支的分析表明，局部垂直夹带和横向平流是冬季dFe浓度增加的主要原因。在初冬，加强的西北风激发了向南的埃克曼输送和西部副北极环流上的埃克曼上升流，将富含dFe的水向南输送。在冬季中后期，亚北极环流的西南边界流和鄂霍次克海的外流也将富含dFe的水带到了俄亥俄地区。在冬季，大气尘埃的dFe预算的贡献是几倍小于这些海洋运输过程。这些结果表明，西风诱导的Ekman输送和环流系统地影响WSNP表面dFe浓度的季节变化。
Iron (Fe) is an essential nutrient for marine phytoplankton and it constitutes an important element in the marine carbon cycle in the ocean. This study examined the mechanisms controlling seasonal variation of dissolved Fe (dFe) in the western subarctic North Pacific (WSNP), using an ocean general circulation model coupled with a simple biogeochemical model incorporating a dFe cycle fed by two major sources (atmospheric dust and continental shelf sediment). The model reproduced the seasonal cycle of observed concentrations of dFe and macronutrients at the surface in the Oyashio region with maxima in winter (February–March) and minima in summer (July–September), although the simulated seasonal amplitudes are a half of the observed values. Analysis of the mixed‐layer dFe budget indicated that both local vertical entrainment and lateral advection are primary contributors to the wintertime increase in dFe concentration. In early winter, strengthened northwesterly winds excite southward Ekman transport and Ekman upwelling over the western subarctic gyre, transporting dFe‐rich water southward. In mid to late winter, the southward western boundary current of the subarctic gyre and the outflow from the Sea of Okhotsk also bring dFe‐rich water to the Oyashio region. The contribution of atmospheric dust to the dFe budget is several times smaller than these ocean transport processes in winter. These results suggest that the westerly wind‐induced Ekman transport and gyre circulation systematically influence the seasonal cycle of WSNP surface dFe concentration.