Propagation and Vertical Structure of the Tidal Flow in Nares Strait
Propagation and Vertical Structure of the Tidal Flow in Nares Strait
复制标题
内雷斯海峡潮汐流的传播和垂直结构
作者：
Davis P
通过纳尔斯海峡向南流动的淡水是北极淡水预算的重要组成部分。在短时间尺度上，海峡的流量由潮汐控制，潮汐动力学可能对较长时期内淡水通量的大小很重要。在这里，我们利用2003年至2006年间部署在纳尔斯海峡的四个底部安装的声学多普勒电流分析器的数据，通过探索其传播和垂直结构，建立了对该地区潮汐的现有知识。我们观察到传播的正压半日潮汐波相互作用形成驻波模式，这解释了在该地区观测到的异常大的潮汐振幅。在海峡方向上，半日潮流随深度变化较大。与此相反，日潮以前进波的形式通过海峡向北传播，潮流大致上是深度不变的。纳尔斯海峡靠近半日临界纬度和埃尔斯米尔岛陡峭的侧壁所施加的地形限制是观测到的垂直变化背后的主要驱动因素。在水柱的上部，斜压活动使潮流振幅增加了25%。在海峡两岸方向，日潮和半日潮均存在两层结构，半日潮在海峡两岸的相位滞后约为四分之一潮汐周期。我们的研究结果表明，当海峡两岸的水流与陡峭的水深相互作用时，在纳瑞斯海峡的侧壁上存在强烈的垂直运动。
The southward freshwater flux through Nares Strait is an important component of the Arctic's freshwater budget. On short time scales, flow through the strait is dominated by the tides, and tidal dynamics may be important for the magnitude of the freshwater flux over longer periods. Here we build upon our existing knowledge of the tides in the region by exploring their propagation and vertical structure using data from four bottom‐mounted Acoustic Doppler Current Profilers deployed in Nares Strait between 2003 and 2006. We observe that propagating barotropic semidiurnal tidal waves interact to create a standing wave pattern, explaining the abnormally large tidal amplitudes that are observed in this region. In the along‐strait direction, semidiurnal tidal currents exhibit strong variations with depth. In contrast, the diurnal tides propagate northward through the strait as progressive waves, and the tidal currents are broadly depth invariant. Proximity of Nares Strait to the semidiurnal critical latitude and the topographical restriction imposed by the steep side wall of Ellesmere Island are primary drivers behind the observed vertical variability. In the upper part of the water column, baroclinic activity increases the tidal current amplitude by up to 25%. In the across‐strait direction, a two‐layer structure exists in both the diurnal and semidiurnal tidal flow, with a phase lag of approximately a quarter of a tidal cycle across the strait for the semidiurnal tide. Our results suggest that strong vertical motion exists against the side walls of Nares Strait, as the across‐strait flow interacts with the steeply sloping bathymetry.