Interannual transport variability of Upper Labrador Sea Water at Flemish Cap
Interannual transport variability of Upper Labrador Sea Water at Flemish Cap
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DOI：
10.1002/2015jc010705
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发表时间：
2015-07
影响因子：
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通讯作者：
Eirini Varotsou;K. Jochumsen;N. Serra;D. Kieke;L. Schneider
中科院分区：
文献类型：
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作者：
Eirini Varotsou;K. Jochumsen;N. Serra;D. Kieke;L. Schneider
利用8 km分辨率数值海洋模式的输出结果，研究了1960-2009年佛兰芒角（47°N/45°W）上拉布拉多海水（ULSW）的输运。由于内部路径的影响，模式中ULSW的平均输送量从53°N的6.7 Sv向南减小到45°N的4.5 Sv。总ULSW体积运输的最大部分去佛兰芒帽内的深西部边界电流（DWBC，72%），但很大一部分通过佛兰芒通行证（20%）。在年际的时间尺度上，在佛兰芒山口的变异表现出明显的行为相比，在DWBC和上游波动的变异。运行相关方法被应用于获得在佛兰芒山口的运输变化与几个数量的连接，代表不同的物理机制：（1）北大西洋涛动指数，（2）埃克曼输送，（3）拉布拉多海超短波形成率，（4）北大西洋海流（NAC）相对于斜坡的位置;（5）副极地环流的平均输送。减弱或加强输送ULSW通过佛兰芒山口与大气强迫的变化或与NAC的位置的变化相一致。在DWBC附近，NAC的强烈蜿蜒减少了佛兰芒角的运输，而ULSW流量被“重新定向”到佛兰芒山口，加强了那里的运输。与此相反，在DWBC的传输变异性主要是由上游的波动和变化，根据ULSW的形成率。
The transport of Upper Labrador Sea Water (ULSW) at Flemish Cap (47°N/45°W) is investigated in the period 1960–2009 using the output from an 8 km resolution numerical ocean model. The average model transport of ULSW decreases southward from 6.7 Sv at 53°N to 4.5 Sv at 45°N due to interior pathways. The largest fraction of the total ULSW volume transport goes around Flemish Cap within the Deep Western Boundary Current (DWBC, 72%) but a significant part goes through Flemish Pass (20%). At interannual timescales, the variability at Flemish Pass shows a distinct behavior when compared to the variability in the DWBC and to the upstream fluctuations. A running correlation method is applied to obtain the connection of the transport variability at Flemish Pass with several quantities, representative for different physical mechanisms: (1) the North Atlantic Oscillation index, (2) the Ekman transport, (3) the rate of ULSW formation in the Labrador Sea, (4) the position of the North Atlantic Current (NAC) relative to the slope and (5) the averaged transport in the subpolar gyre. Weakened or strengthened transport of ULSW through Flemish Pass coincides with changes of the atmospheric forcing or with changes of the NAC‘s position. Strong meandering of the NAC close to the DWBC reduces the transport off Flemish Cap, and the ULSW flow is “redirected” into the Flemish Pass, enhancing the transport there. In contrast, the transport variability in the DWBC is mainly caused by upstream fluctuations and changes according to the rate of ULSW formation.