AI 中文总结
研究大西洋经向翻转环流转变，开发仅用过去数据估计记忆算子最慢模式的诊断方法，其算子集合能提前77年发出警报，可作为接近度度量，信号取决于长期记忆和垂直翻转结构。
AI 中文摘要
经典的早期预警信号假设在临界点附近恢复会变慢，但在一个经过充分研究的大西洋经向翻转环流崩溃的气候系统模式模拟中，自相关和方差反而减小。我们开发了一种预先注册的诊断方法，该方法仅使用过去的数据来估计与不断演变的翻转结构相匹配的记忆算子的最慢模式。算子集合在崩溃前77年发出探索性警报，而基于物理的淡水输送指标则为29年。在恢复分支上的盲测并未验证相同的时间规则，这支持将该诊断解释为一种接近度度量而非通用时钟。在另外九个模拟中，它在所有四个有限速率强迫转变之前发出警告，但在仅作为标量大西洋经向翻转环流记录可用的三个快速噪声诱导崩溃之前没有发出警告。匹配的消融表明，该信号取决于长期记忆和垂直翻转结构，而不仅仅取决于趋势力或多变量信息。
英文摘要
Classical early-warning signals assume that recovery slows near a tipping point, but in a well-studied CESM simulation of AMOC collapse, autocorrelation and variance decrease instead. We develop a preregistered diagnostic that uses only past data to estimate the slowest mode of a memory operator fitted to the evolving overturning structure. The operator ensemble produces an exploratory alarm 77 years before collapse, compared with 29 years for a physics-based freshwater-transport indicator. A blind test on the recovery branch does not validate the same timing rule, supporting interpretation of the diagnostic as a proximity measure rather than a universal clock. In nine additional simulations, it warns before all four finite-rate forced transitions but not before three rapid noise-induced collapses available only as scalar AMOC records. Matched ablations show that the signal depends on long-timescale memory and vertical overturning structure rather than trend, forcing, or multivariate information alone.
