On the Seasonal Signal of the Filchner Overflow, Weddell Sea, Antarctica
On the Seasonal Signal of the Filchner Overflow, Weddell Sea, Antarctica
复制标题
DOI：
10.1175/jpo-d-13-0180.1
复制
发表时间：
2014-04-01
影响因子：
3.5
通讯作者：
Fer, I.
中科院分区：
文献类型：
--
作者：
Darelius, E.;Strand, K. O.;Fer, I.
南极威德尔海西南部菲尔什纳-罗恩冰架下形成的冷冰架水通过菲尔什内尔凹陷逃离冰架洞穴，以1.6Sverdraps(Sv；1 Sv相当于10(6)m(3)S(-1))的速度溢出到冰架底部，从而对威德尔海底层水的产生做出了重要贡献。在这里，作者研究了该地区所有可用的观测数据--包括来自费尔奇内尔平台的长达五年的系泊数据--以检查外流的季节性变化。据发现，ISW流出的温度随季节变化0.07摄氏度，最大值在4月份。伴随的盐度信号产生了密度为0.03-0.04 kg m(-3)的季节性信号，潜在地改变了ISW羽流的穿透深度超过500m。与最近的模拟相反，观测结果显示流出速度没有季节性变化。在基岩观察到的季节性，至少部分是由于来自伯克纳银行的高盐度陆架水的混合。然而，观测和数值模拟表明，上游环流(即在冰架空洞和费尔奇纳凹陷中)的季节性信号--尽管过程和联系尚不清楚--可能有助于在基准处观察到的季节性信号。在基准面下游的羽状区，源变率仅在ISW羽状物最密集的部分才明显。在羽流中稀释程度较高的部分，来源的可变性被陆架断裂时夹带的水的特性的季节性所克服。这将对生成的底水的性质产生影响。
The cold ice shelf water (ISW) that formed below the Filchner-Ronne Ice Shelf in the southwestern Weddell Sea, Antarctica, escapes the ice shelf cavity through the Filchner Depression and spills over its sill at a rate of 1.6 Sverdrups (Sv; 1 Sv equivalent to 10(6) m(3) s(-1)), thus contributing significantly to the production of Weddell Sea Bottom Water. Here, the authors examine all available observational data from the region-including five year-long time series of mooring data from the Filchner sill-to examine the seasonal variability of the outflow. The temperature of the ISW outflow is found to vary seasonally by 0.07 degrees C with a maximum in April. The accompanying signal in salinity causes a seasonal signal in density of 0.03-0.04 kg m(-3), potentially changing the penetration depth of the ISW plume by more than 500 m. Contrary to recent modeling, the observations show no seasonal variability in outflow velocity. The seasonality observed at the sill is, at least partly, due to the admixture of high-salinity shelf water from the Berkner Bank. Observations and numerical modeling suggest, however, seasonal signals in the circulation upstream (i.e., in the ice shelf cavity and in the Filchner Depression) that-although processes and linkages are unclear-are likely to contribute to the seasonal signal observed at the sill. In the plume region downstream of the sill, the source variability is apparent only within the very densest portions of the ISW plume. In the more diluted part of the plume, the source variability is overcome by the seasonality in the properties of the water entrained at the shelf break. This will have implications for the properties of the generated bottom waters.