We explore dense water cascading (DWC), a type of bottom‐trapped gravity current, on multidecadal time scales using a pan‐Arctic regional ocean‐ice model. DWC is particularly important in the Arctic Ocean as the main mechanism of ventilation of interior waters when open ocean convection is blocked by strong density stratification. We identify the locations where the most intense DWC events occur and evaluate the associated cross‐shelf mass, heat, and salt fluxes. We find that the modeled locations of cascading agree well with the sparse historical observations and that cascading is the dominant process responsible for cross‐shelf exchange in the boundary layers. Simulated DWC fluxes of 1.3 Sv (1 Sv = 10⁶ m³/s) in the Central Arctic are comparable to Bering Strait inflow, with associated surface and benthic Ekman fluxes of 0.85 and 0.58 Sv. With ice decline, both surface Ekman flux and DWC fluxes are increasing at a rate of 0.023 and 0.0175 Sv/year, respectively. A detailed analysis of specific cascading sites around the Beaufort Gyre and adjacent regions shows that autumn upwelling of warm and saltier Atlantic waters on the shelf and subsequent cooling and mixing of uplifted waters trigger the cascading on the West Chukchi Sea shelf break. Lagrangian particle tracking of low salinity Pacific waters originating at the surface in the Bering Strait shows that these waters are modified by brine rejection and cooling, and through subsequent mixing become dense enough to reach depths of 160–200 m.

中文翻译：

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北冰洋密集水域的热点：对太平洋水路的启示

我们使用泛北极区域海冰模型在数十年的时间尺度上探索了浓水级联（DWC），一种底陷重力流。DWC在北冰洋特别重要，因为当强对流层层阻塞了开放海洋对流时，DWC是内部水通风的主要机制。我们确定最严重的DWC事件发生的位置，并评估相关的跨架质量，热量和盐通量。我们发现，级联的建模位置与稀疏的历史观测结果非常吻合，级联是边界层中跨架交换的主要过程。模拟的DWC通量为1.3 Sv（1 Sv = 10 ⁶  m ³/ s）与白令海峡的流入量相当，相关的地表和底栖埃克曼通量分别为0.85和0.58 Sv。随着冰的减少，表面埃克曼通量和DWC通量分别以每年0.023和0.0175 Sv的速度增加。对Beaufort Gyre周围及邻近地区特定级联站点的详细分析表明，架子上大西洋的温暖咸水的秋季上升，以及随后升高的水的冷却和混合触发了西楚科奇海架子断裂的级联。对源自白令海峡表层的低盐度太平洋水的拉格朗日粒子追踪表明，这些水受到盐水排泄和冷却的作用而改变，并通过随后的混合变得足够稠密，可达到160-200 m的深度。