A data assimilation approach to last millennium temperature field reconstruction using a limited high-sensitivity proxy network
A data assimilation approach to last millennium temperature field reconstruction using a limited high-sensitivity proxy network
复制标题
使用有限高灵敏度代理网络重建上千年温度场的数据同化方法
DOI：
10.1175/jcli-d-20-0661.1
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发表时间：
2021
影响因子：
4.9
通讯作者：
Wilson, Rob
中科院分区：
文献类型：
--
作者：
King, Jonathan M.;Anchukaitis, Kevin J.;Tierney, Jessica E.;Hakim, Gregory J.;Emile-Geay, Julien;Zhu, Feng;Wilson, Rob
我们使用北半球树木年轮网络发展（NTREND）树木年轮数据库来检验使用一个小的、高度敏感的代理网络同化过去一千年的古温度数据的效果。我们首先使用伪代理实验来评估我们的方法。这表明，利用该网络对北半球温带地区的空间同化效果较好，比以往基于逐点回归的NTREND重建结果有所改善。我们还发现，当站点数量变少时，我们的方法对气候模式偏差很敏感。在这些实验的基础上，我们吸收了真实的NTREND网络。为了量化模型先前的不确定性，我们制作了10个单独的重建，每个重建都吸收了一个不同的气候模型。在公元1100年之前，当网络变得稀疏时，这些重建最不相似，但随着网络的增长，这些重建显示出更大的一致性。公元1100年以前的时间变异性也被低估了。我们的同化方法产生了空间不确定性估计，这些估计确定了北美和东西伯利亚的树木线是最受益于新千年长度的温度敏感树木年轮记录的地区。我们将我们的多模式平均重建与五种现有的古温度产品进行比较，以检验重建对辐射强迫的响应范围。我们发现，在中世纪和小冰期之间的过渡时期，对火山爆发的重建响应的空间格局和幅度存在实质性差异。这些现存的不确定性要求发展古气候重建比较框架，以系统地检查代理网络组成和重建方法的后果，并继续扩大树轮代理网络。
We use the Northern Hemisphere Tree-Ring Network Development (NTREND) tree-ring database to examine the effects of using a small, highly sensitive proxy network for paleotemperature data assimilation over the last millennium. We first evaluate our methods using pseudoproxy experiments. These indicate that spatial assimilations using this network are skillful in the extratropical Northern Hemisphere and improve on previous NTREND reconstructions based on point-by-point regression. We also find our method is sensitive to climate model biases when the number of sites becomes small. Based on these experiments, we then assimilate the real NTREND network. To quantify model prior uncertainty, we produce 10 separate reconstructions, each assimilating a different climate model. These reconstructions are most dissimilar prior to 1100 CE, when the network becomes sparse, but show greater consistency as the network grows. Temporal variability is also underestimated before 1100 CE. Our assimilation method produces spatial uncertainty estimates, and these identify tree-line North America and eastern Siberia as regions that would most benefit from development of new millennial-length temperature-sensitive tree-ring records. We compare our multimodel mean reconstruction to five existing paleotemperature products to examine the range of reconstructed responses to radiative forcing. We find substantial differences in the spatial patterns and magnitudes of reconstructed responses to volcanic eruptions and in the transition between the Medieval epoch and Little Ice Age. These extant uncertainties call for the development of a paleoclimate reconstruction intercomparison framework for systematically examining the consequences of proxy network composition and reconstruction methodology and for continued expansion of tree-ring proxy networks.