Variability of the Ross Gyre, Southern Ocean: Drivers and Responses Revealed by Satellite Altimetry
Variability of the Ross Gyre, Southern Ocean: Drivers and Responses Revealed by Satellite Altimetry
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DOI：
10.1029/2018gl078607
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发表时间：
2018-06-28
影响因子：
5.2
通讯作者：
Meredith, Michael P.
中科院分区：
文献类型：
--
作者：
Dotto, Tiago S.;Garabato, Alberto Naveira;Meredith, Michael P.
2011-2015年南极洲罗斯环流（RG）的全年变率利用雷达测高得到。RG的特点是有界的再循环成分和向西的贯穿流。揭示了海面高度和海面应力旋度的两种变率模态。第一个是由南极涛动引起的大尺度海面高度变化。第二个是由与阿蒙森海低压相关的海平面压力波动所驱动的环流面积和强度的半年变化。贯穿流的变化也与阿蒙森海低压有关。只有在海洋表面应力中考虑到海冰阻力时，才能对海洋环流进行充分的描述。这里阐明的RG变率的驱动因素对我们理解南极冰盖融化的海洋强迫及其海洋清新足迹的下游传播具有重要意义。罗斯环流是南大洋的主要洋流系统之一，向南太平洋板块的冷大陆架输送热量，从而影响各种冰架的稳定性。由于季节性的海冰覆盖，测量很少，而且对环流的可变性及其驱动力知之甚少。在这里，我们使用卫星雷达测高来产生关于罗斯环流变异性的新光。确定了两个关键方面：(i)由绕南极洲流动的纬向风驱动的海面高度的大尺度变化；（ii）与调节当地气象和海冰条件的区域低压中心有关的环流面积和强度的变化。同样的压力系统调节着沿海洋流的强度，这可能会影响罗斯海关键海洋属性的分布。本研究中确定的过程对我们理解南极冰盖融化的海洋强迫及其海洋清新足迹的下游传播具有重要意义。
Year-round variability in the Ross Gyre (RG), Antarctica, during 2011-2015, is derived using radar altimetry. The RG is characterized by a bounded recirculating component and a westward throughflow to the south. Two modes of variability of the sea surface height and ocean surface stress curl are revealed. The first represents a large-scale sea surface height change forced by the Antarctic Oscillation. The second represents semiannual variability in gyre area and strength, driven by fluctuations in sea level pressure associated with the Amundsen Sea Low. Variability in the throughflow is also linked to the Amundsen Sea Low. An adequate description of the oceanic circulation is achieved only when sea ice drag is accounted for in the ocean surface stress. The drivers of RG variability elucidated here have significant implications for our understanding of the oceanic forcing of Antarctic Ice Sheet melting and for the downstream propagation of its ocean freshening footprint.Plain Language Summary The Ross Gyre is one of the main current systems of the Southern Ocean and conveys heat toward the cold continental shelves of the Antarctic Pacific sector, thus impacting the stability of diverse ice shelves. Due to the seasonal sea ice cover, measurements are sparse and little is known about the variability of the gyre's circulation and its driving forces. Here we use satellite radar altimetry to generate new light on the Ross Gyre variability. Two key aspects are identified: (i) large-scale variability of the sea surface height driven by the zonal winds that flow around Antarctica and (ii) changes in area and strength of the gyre, which are linked to a regional center of low pressure that modulates the local meteorology and sea ice conditions. This same pressure system regulates the strength of the coastal currents, which potentially impacts on the distribution of key oceanic properties toward the Ross Sea. The processes identified in this study have strong implications for our understanding of the oceanic forcing of Antarctic Ice Sheet melting and for the downstream propagation of its ocean freshening footprint.