On the Kuroshio Extension near the Emperor Seamounts
On the Kuroshio Extension near the Emperor Seamounts
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靠近皇帝海山的黑潮延伸区
DOI：
10.1029/jc092ic04p03827
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发表时间：
1987
影响因子：
--
通讯作者：
B. Taft
中科院分区：
文献类型：
--
作者：
I. Hamann;B. Taft
1982年6 - 7月和1983年11月，对沿167°E方向的黑潮延伸带的垂直结构和海流接近天皇海山链的路径进行了研究；此外，还获得了三个位置（两个位于东经167°，另一个位于皇帝海山链的主间隙）的系泊流速仪的记录。1982年和1983年的黑潮延伸带在接近链条时转为气旋（曲波长度为450公里）；1982年表层流轴线位于深水区（>3.5 km）， 1983年位于相对浅水区（0.5 km）。1982年水平温度梯度减小，2000 m以下的密度面随着黑潮延伸流过天皇海山而上升。在这两年中，都没有证据表明水流在穿过海底山时发生了分裂。与1982年相比，1983年水平温度梯度没有减弱，黑潮伸展作用于金美海山的极浅部分（< 500 m）。在进行水文剖面时进行的海流测量表明，瞬时黑潮延伸到海底（深海东流2 cm s - 1）。深层低频涡旋动能介于152°E和158°W之间，表明深层涡旋活动大规模向东减弱。东经167°3500 m附近纬向平均流量基本为零（0.1 cm s−1）；平均子午分量较大（- 2.1和- 0.7 cm s - 1）。在裂谷南侧，深流异常稳定（KE/KM < 1），流向北太平洋东部盆地；与167°E （O(10-100)）相比，在较低的温跃层中也观察到低比率（O(1)）。间隙动能的频率含量与167°E不同，最高频带（2小时< P < 2天）能量最大，而167°E中尺度频带（20天< P < 150天）能量最大。裂缝中的流动在许多特征上与在另外两个河道中观察到的流动相似：Vema河道和Charlie Gibbs断裂带。
In June–July 1982 and November 1983, studies were carried out of the vertical structure of the Kuroshio Extension along 167°E and the path of the current as it approached the Emperor Seamount chain; in addition, records from moored current meters at three locations (two at 167°E and one in the Main Gap of the Emperor Seamount chain) were obtained. The Kuroshio Extension in both 1982 and 1983 turned cyclonically (meander wave length of 450 km) as it approached the chain; the axis of the surface current was located in deep water (>3.5 km) in 1982 and in relatively shallow water (0.5 km) in 1983. In 1982 the horizontal temperature gradient decreased, and the density surfaces down to 2000 m ascended as the Kuroshio Extension flowed over the Emperor Seamounts. In neither year was there evidence of current splitting as it crossed the seamounts. In 1983, in contrast to 1982, there was no weakening of the horizontal temperature gradient, and the Kuroshio Extension went over a very shallow portion of Kinmei Seamount ( < 500 m). The current measurements made at the time of the hydrographic section show that the instantaneous Kuroshio extended to the bottom (abyssal eastward current of 2 cm s−1). The deep low-frequency eddy kinetic energy values are intermediate between those measured at 152°E and those at 158°W, suggesting a large-scale eastward decrease in deep eddy activity. Zonal mean flow near 3500 m at 167°E was essentially zero (0.1 cm s−1); the mean meridional components were larger (−2.1 and −0.7 cm s−1). At the southern side of the gap the deep flow was unusually steady (KE/KM < 1) and directed northeastward into the eastern basin of the North Pacific; low ratios (O(1)) were also observed in the lower thermocline compared with those at 167°E (O(10–100)). The frequency content of the gap kinetic energy differed from that measured at 167°E: the highest frequency band (2 hours < P < 2 days) was the most energetic, whereas at 167°E the mesoscale band (20 days < P < 150 days) was the most energetic. The flow in the gap resembles in many of its characteristics that observed in two other channel flows: the Vema Channel and the Charlie Gibbs Fracture Zone.