Dissolved Fe Supply to the Central Gulf of Alaska Is Inferred to Be Derived From Alaskan Glacial Dust That Is Not Resolved by Dust Transport Models
Dissolved Fe Supply to the Central Gulf of Alaska Is Inferred to Be Derived From Alaskan Glacial Dust That Is Not Resolved by Dust Transport Models
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DOI：
10.1029/2021jg006323
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发表时间：
2021-06-01
影响因子：
3.7
通讯作者：
Crusius, John
中科院分区：
文献类型：
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作者：
Crusius, John
重新检查之前公布的阿拉斯加湾中部海洋站Papa的溶解铁时间序列数据，发现在连续几年的9月至2月期间，溶解铁库存增加了33%-70%，这意味着该地区在秋季或初冬期间有铁的来源。因为我几乎可以排除每年这个时候许多可能的铁源，我建议阿拉斯加冰川尘埃是可能的铁源。众所周知，在秋季，由异常的离岸风定期产生大量此类尘埃，并通过山缝同时从几个地点产生，横跨阿拉斯加湾北部海岸线约1000公里。在秋季，当低于冰点、低湿度的空气温度持续许多天时，就会发生大的沙尘通量事件。我认为，现有的最先进的全球尘埃模型无法再现阿拉斯加的尘埃流，因为模型的空间分辨率太粗糙，无法解决通过产生尘埃的狭窄山缝的大风。未来的工作可能有助于向中部GOA确认这一铁源，包括铁浓度的时间序列曲线，以及来自配备传感器的剖面浮标的辅助信息。如果这种向果阿中部供应铁的机制得到证实，这将意味着阿拉斯加的尘埃被输送到距离海岸1100公里的地方，是卫星观测目测记录距离的两倍多。
Re-examination of previously published dissolved iron time-series data from Ocean Station Papa in the central Gulf of Alaska (GoA) reveals 33%-70% increases in the dissolved iron inventories occurring between September and February of successive years, implying a source of Fe to this region during autumn or early winter. Because I can virtually rule out many possible iron sources at this time of year, I suggest Alaskan glacial dust is the likely iron source. Large plumes of such dust are known to be generated regularly in the autumn by anomalous offshore winds and channeled through mountain gaps, simultaneously from several locations spanning similar to 1,000 km of the northern Gulf of Alaska coastline. Large dust flux events occur when below-freezing, low-humidity air temperatures persist for many days during the autumn. I suggest that existing state-of-the-art global dust models fail to reproduce this Alaskan dust flux because the model spatial resolution is too coarse to resolve the high winds through the narrow mountain gaps that generate the dust. Future work that could help to confirm this Fe source to the central GoA includes time-series profiles of iron concentrations, and ancillary information from sensor-equipped profiling floats. If this mechanism of Fe supply to the central GoA were confirmed, it would imply this Alaskan dust is transported >= 1,100 km from the coast, more than twice as far as has been visually documented from satellite observations.