AI 中文总结
该研究通过五箱模型证明印度-太平洋门户对北大西洋盐分输出仅为加性强迫，不影响平衡态，但通过记忆核影响瞬态振荡稳定性，且振荡失稳先于鞍结。
AI 中文摘要
通过印度-太平洋门户的跨海盆交换为北大西洋提供盐分，并被广泛认为是控制大西洋翻转环流稳定性的因素。我们探究这种控制能否作用于一个概念性温盐环流模型的平衡结构。我们构建了一个具有精确盐量不变量的封闭五箱模型，包括北大西洋、上层环流、印度洋、太平洋和深层水库，回流分为通过印度洋水库的暖路径和冷路径，并包含印度尼西亚贯穿流分支和阿古拉斯回流。加入门户水库的稳态收支表明，所有内部交换相互抵消，因此它们向大西洋输出的盐分仅由大西洋净淡水输出决定。这一结论独立于暖路径比例、贯穿流、回流以及输出在门户水库间的分配方式；在参数扫描中，最大偏差约为十的负十一次方。因此，门户仅作为纯加性强迫进入，不能重整化盐平流反馈。将离散输运滞后替换为伽马记忆核，平衡态保持不变，但得到仅取决于核形状的振荡不稳定性阈值的闭式解。宽记忆具有强稳定性，而离散滞后是族中最不稳定的成员。由于瞬时反馈在折叠点处消失，振荡不稳定性总是先于鞍结出现，其区间随记忆锐化而扩大十倍以上。因此，门户似乎作用于瞬态而非平衡态动力学。
英文摘要
Interbasin exchange through the Indo-Pacific gateway supplies salt to the Atlantic and is widely invoked as a control on the stability of the Atlantic overturning circulation. We ask whether that control can act on the equilibrium structure of a conceptual thermohaline model. A closed five-box model with an exact salt invariant is constructed, comprising North Atlantic, upper-limb, Indian, Pacific, and deep reservoirs, with the return flow split between a warm route through the Indian reservoir and a cold route, together with an Indonesian Throughflow branch and an Agulhas retroflection. Adding the steady-state budgets of the gateway reservoirs shows that every internal exchange cancels, so the salt they export to the Atlantic is fixed by the net Atlantic freshwater export alone. This holds independently of the warm-route fraction, the throughflow, the retroflection, and how the export is apportioned among gateway reservoirs; across a parameter sweep the largest departure is of order ten to the minus eleven. The gateway therefore enters as a purely additive forcing and cannot renormalize the salt-advection feedback. Replacing the discrete transit lag by a gamma memory kernel leaves the equilibria unchanged but yields a closed-form threshold for oscillatory instability depending only on kernel shape. Broad memory is strongly stabilizing, and a discrete lag is the least stable member of the family. Because the instantaneous feedback vanishes at the fold, oscillatory instability always precedes the saddle-node, over an interval widening more than tenfold as memory sharpens. Gateways therefore appear to act on transient rather than equilibrium dynamics
Comments16 pages, 7 figures, 3 tables
