Sensitivity of the Relationship Between Antarctic Ice Shelves and Iron Supply to Projected Changes in the Atmospheric Forcing
Sensitivity of the Relationship Between Antarctic Ice Shelves and Iron Supply to Projected Changes in the Atmospheric Forcing
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DOI：
10.1029/2022jc019210
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发表时间：
2023-02-01
影响因子：
3.6
通讯作者：
van Dijken, Gert L.
中科院分区：
文献类型：
--
作者：
Dinniman, Michael S.;St-Laurent, Pierre;van Dijken, Gert L.
由冰架融化速率引起的环流变化引起的富铁深水的向上平流或混合是南极大陆架上沿海多尼雅海区叶绿素a生产的主要控制因素。这里，用一个5公里分辨率的南大洋海洋/海冰/冰架模式，研究了2100年预测的大气变化对这一关系的影响，其中包括不同的模拟溶解铁源和理想的生物吸收。大气变化被作为理想的增量添加到强迫中。加上极地移动和风的加强，降水增加，大气温度变暖，导致进入大陆架的热量翻了一番，南极冰架底部融化总量增加了83%。大陆架上表层水的总溶解铁供应量增加了62%，而仅由于基底熔体驱动的倾覆而产生的表层铁供应量增加了48%。然而，尽管平均而言，冰架对铁供应总量的贡献变得不那么重要(占总供应量的29%)，但在阿蒙森海和别林豪森海等一些地区，冰架的参与变得相对更重要。大气条件的改变也导致夏季海冰范围的减少和夏季混合层的浅化。这些对预计变化的模拟反应表明，南极大陆架上浮游植物大量繁殖的光和营养限制得到了缓解，未来几年可能会增加年产量。
Upward advection or mixing of iron-rich deep waters due to circulation changes driven by the rate of basal ice shelf melt was shown to be a primary control on chlorophyll a production in coastal polynyas over the Antarctic continental shelf. Here, the effects of atmospheric changes projected in 2100 on this relationship were examined with a 5-km resolution ocean/sea ice/ice shelf model of the Southern Ocean with different simulated dissolved iron sources and idealized biological uptake. The atmospheric changes are added as idealized increments to the forcing. Inclusion of a poleward shift and strengthening of the winds, increased precipitation, and warmer atmospheric temperatures resulted in doubling of the heat advected onto the continental shelf and an 83% increase in the total Antarctic ice shelf basal melt. The total dissolved iron supply to the surface waters over the continental shelf increased by 62%, while the surface iron supply due just to basal melt driven overturning increased by 48%. However, even though the ice shelf driven contribution becomes less important to the total iron supply on average (29% of total), the ice shelf involvement becomes relatively even more important in some locations, such as the Amundsen and Bellingshausen Seas. The modified atmospheric conditions also produced a reduction in summer sea ice extent and a shoaling of the summer mixed layers. These simulated responses to projected changes suggest relief of light and nutrient limitation for phytoplankton blooms over the Antarctic continental shelf and perhaps an increase in annual production in years to come.