High-Frequency Variability in the Circulation and Hydrography of the Denmark Strait Overflow from a High-Resolution Numerical Model
High-Frequency Variability in the Circulation and Hydrography of the Denmark Strait Overflow from a High-Resolution Numerical Model
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DOI：
10.1175/jpo-d-17-0129.1
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发表时间：
2017-12-01
影响因子：
3.5
通讯作者：
Mastropole, Dana
中科院分区：
文献类型：
--
作者：
Almansi, Mattia;Haine, Thomas W. N.;Mastropole, Dana
初步结果来自为期一年的高分辨率（类似于2公里）数值模拟，覆盖了东格陵兰大陆架、冰岛海和伊尔明格海。丹麦海峡附近的水文和环流模式与现有观测资料吻合较好。本文研究了丹麦海峡溢流（DSO）的变异性，通过探测和表征海峡中两种主要的中尺度特征——波和脉冲。作者估计，在球团和脉冲存在的情况下，DSO向南的年平均体积通量约增加30%。平均而言，脉冲长度为57.1（27.5）小时，每3.2（5.5）天发生一次，在夏季（冬季）更频繁。脉冲增大（减小）溢流截面积，溢流界面周围温度降低（升高）约2.6℃（1.8℃）。丸的横向范围比脉冲的横向范围大得多。在这两种情况下，沿海峡向赤道方向的密集水流都增强了，但脉冲水流的增强更大。海面高度（SSH）在丸期间上升4-10厘米，在脉冲期间上升5厘米。在波束（脉冲）期间，SSH异常轮廓形成一个碗状（圆顶），两个特征以稍微不同的方向穿过海峡。横流改变方向；脉冲（脉冲）与水平电流的转向（后退）有关。该模式表明，球和脉冲在控制DSO向伊尔明格海输送的变化中起主要作用。
Initial results are presented from a yearlong, high-resolution (similar to 2 km) numerical simulation covering the east Greenland shelf and the Iceland and Irminger Seas. The model hydrography and circulation in the vicinity of Denmark Strait show good agreement with available observational datasets. This study focuses on the variability of the Denmark Strait overflow (DSO) by detecting and characterizing boluses and pulses, which are the two dominant mesoscale features in the strait. The authors estimate that the yearly mean southward volume flux of the DSO is about 30% greater in the presence of boluses and pulses. On average, boluses (pulses) are 57.1 (27.5) h long, occur every 3.2 (5.5) days, and are more frequent during the summer (winter). Boluses (pulses) increase (decrease) the overflow cross-sectional area, and temperatures around the overflow interface are colder (warmer) by about 2.6 degrees C(1.8 degrees C). The lateral extent of the boluses is much greater than that of the pulses. In both cases the along-strait equatorward flow of dense water is enhanced but more so for pulses. The sea surface height (SSH) rises by 4-10 cm during boluses and by up to 5 cm during pulses. The SSH anomaly contours form a bowl (dome) during boluses (pulses), and the two features cross the strait with a slightly different orientation. The cross streamflow changes direction; boluses (pulses) are associated with veering (backing) of the horizontal current. The model indicates that boluses and pulses play a major role in controlling the variability of the DSO transport into the Irminger Sea.