Abstract Over the past decade, dendrochronologists have increasingly adopted the signal-free detrending (SFD) method to remove age-size trends in tree-ring measurement series, amplify the common stand-wide signal in composite chronologies, and recover medium- to low-frequency patterns that may be inadvertently removed by other detrending approaches. However, since its introduction in 2008, no systematic evaluation of the effects of SFD on tree-ring chronologies has been performed. Here we conduct the first review of SFD in dendrochronology and assess its effects when applied to large tree-ring networks. We analyzed the PAGES North America 2 K database of nearly 300 temperature-sensitive chronologies and the Missouri River database of over 350 chronologies curated for the purpose of reconstructing Missouri River streamflow. Both databases contain multiple versions of each chronology generated by different detrending methods, including those produced with (and without) the signal-free procedure applied. We evaluated (i) whether SFD increases chronology coherence at the site level by boosting the between-tree agreement, (ii) whether SFD increases coherence on a regional basis by making neighboring chronologies more similar to each other, and (iii) whether signal-free chronologies retained more medium- to low-frequency variability than their traditional counterparts. We find that, while SFD increased the strength of common signals in many instances, the effect was not universal and some sites even show a decrease in signal coherence. At regional scales, SFD increases chronology coherence in temperature-sensitive records but had no detectable effect on moisture-sensitive records. Our results demonstrate the importance of evaluating the effects of SFD prior to deploying this method for chronology development and paleoclimate reconstruction.

中文翻译：

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无信号去趋势是否会增加大型树轮网络中的时序一致性？

摘要 在过去的十年中，树木年代学家越来越多地采用无信号去趋势 (SFD) 方法来消除树轮测量系列中的年龄大小趋势，放大复合年表中的常见全站信号，并恢复中到低可能会被其他去趋势方法无意中删除的频率模式。然而，自 2008 年推出以来，尚未对 SFD 对树木年轮年表的影响进行系统评估。在这里，我们对树木年代学中的 SFD 进行了首次审查，并评估了其应用于大型树轮网络时的效果。我们分析了近 300 个温度敏感年表的 PAGES North America 2 K 数据库和为重建密苏里河水流而策划的 350 多个年表的密苏里河数据库。两个数据库都包含由不同去趋势方法生成的每个年表的多个版本，包括那些使用（和不使用）无信号程序生成的版本。我们评估了 (i) SFD 是否通过提高树间一致性来增加站点级别的年表一致性，(ii) SFD 是否通过使相邻年表彼此更相似来增加区域的一致性，以及 (iii) 是否信号-自由年表比传统年表保留了更多的中低频变化。我们发现，虽然 SFD 在许多情况下增加了常见信号的强度，但效果并不普遍，一些站点甚至显示出信号相干性的降低。在区域尺度上，SFD 增加了温度敏感记录的年表连贯性，但对湿度敏感记录没有可检测的影响。我们的结果证明了在将这种方法部署到年代学发展和古气候重建之前评估 SFD 影响的重要性。