Circulation and cross-shelf exchanges in the Malvinas Islands Shelf region
Circulation and cross-shelf exchanges in the Malvinas Islands Shelf region
复制标题
马尔维纳斯群岛陆架区域的流通和跨大陆架交换
DOI：
10.1016/j.pocean.2021.102666
复制
发表时间：
2021
影响因子：
4.1
通讯作者：
Combes, Vincent
中科院分区：
文献类型：
--
作者：
Palma, Elbio D.;Matano, Ricardo P.;Combes, Vincent
马尔维纳斯群岛大陆架 (MIS) 涵盖西南大西洋生产力最高的部分之一。构成海洋食物网基础的大量浮游植物从 MIS 北部出现，并沿着巴塔哥尼亚陆架折断区向北延伸数百公里。人们对 MIS 受精的物理过程知之甚少。在这里，我们使用高分辨率海洋模型的结果来描述 MIS 和南大洋之间的环流和水体交换，并确定陆架水域施肥的物理过程。模型结果表明，陆架西南地区呈现夏季加强、冬季减弱的反气旋环流模式。这些岛屿的阻挡作用导致在MIS北部形成逆风西流流，在西部形成再循环单元，并在将它们分开的狭窄海峡中形成向北的通流。粒子追踪实验表明，德雷克海峡北部是 MIS 最大的水源。被动示踪剂表明，南极绕极流与MIS碰撞处是深水出露的主要地点。随后的露头很大程度上是由潮汐和风力的协同相互作用驱动的。沿着西南陆架折线传播后，示踪剂浓度在冬季达到峰值，并在春季衰减。夏季，示踪剂积聚在岛屿的背风处，与叶绿素 a 浓度的卫星图像一致。其他实验表明，MIS 水域对巴塔哥尼亚陆架断裂前沿有重要贡献。
The Malvinas Islands Shelf (MIS) encompasses one of the most productive portions of the southwestern Atlantic. Large phytoplankton blooms, which constitute the base of the marine food web, emerge from the northern sector of the MIS and extend hundreds of kilometers northward along the Patagonian shelfbreak. The physical processes contributing to MIS fertilization are poorly understood. Here we use the results of a high‐resolution ocean model to characterize circulation and water mass exchanges between the MIS and the Southern Ocean, as well as to identify the physical processes underlying fertilization of the shelf waters. Model results show that the shelf is characterized by an anticyclonic circulation pattern in the southwestern region that intensifies during summer and weakens during winter. The blocking effect of the islands leads to development of an upwind westward-flowing current in the northern portion of the MIS, recirculation cells in the western portion, and a northward throughflow in the narrow strait separating them. Particle tracking experiments reveal that the northern portion of the Drake Passage is the largest water mass source for the MIS. Passive tracers indicate that the place where the Antarctic Circumpolar Current collides with the MIS is the main site for the outcropping of deep waters. Subsequent outcropping is largely driven by the synergetic interaction of tides and wind forcing. After spreading along the southwestern shelfbreak, the concentration of tracer peaks in the winter and decays during the spring. In summer, the tracer accumulates on the lee of the islands in agreement with satellite images of chlorophyll-a concentration. Additional experiments show that there is an important contribution of MIS waters to the Patagonian shelfbreak front.