Emergent constraints on the large scale atmospheric circulation and regional hydroclimate: do they still work in CMIP6 and how much can they actually constrain the future?
Emergent constraints on the large scale atmospheric circulation and regional hydroclimate: do they still work in CMIP6 and how much can they actually constrain the future?
复制标题
对大规模大气环流和区域水文气候的新兴约束：它们在 CMIP6 中是否仍然有效？它们实际上能在多大程度上限制未来？
DOI：
10.1175/jcli-d-21-0055.1
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发表时间：
2021
影响因子：
4.9
通讯作者：
Di Chen
中科院分区：
文献类型：
--
作者：
I. Simpson;K. McKinnon;F. V. Davenport;M. Tingley;F. Lehner;A. A. Fahad;Di Chen
“紧急约束”（EC）是一种统计关系，在模式集合中，当前气候的一个可测量方面（预测因子）和未来预测气候变化的一个方面（预测因子）之间。如果这样的关系是鲁棒的并且是可理解的，则它可以为真实的世界提供受约束的投影。在这里，耦合模型相互比较项目6（CMIP 6）模型被用来重新审视先前模型相互比较中提出的几个EC，其目的有两个：（1）评估这些EC是否能经受住CMIP 6的部分样本外检验;（2）比以前的研究更严格地量化受约束的预测变化。为了实现后者，提出的方法，其中的不确定性可以适当占，包括内部变异的影响，线性关系的不确定性，以及与模型结构差异相关的不确定性，除了那些由EC描述。使用最小二乘回归和贝叶斯分层模型。评估了三个EC：（a）南半球急流纬度与预计急流偏移之间的关系，据认为，这是对未来预测的一个有力和有用的定量限制;（B）太平洋-北美区的驻波振幅与北美上空纬向风变化之间的关系（包括水文气候），这被认为是稳健的，但CMIP 6中预测器的改进导致其不再实质上限制环流或水文气候;和（c）ENSO遥相关到加州和加州降水变化之间的关系，当使用历史ENSO遥相关作为预测因子时，这种关系似乎不稳定。
An ‘emergent constraint’ (EC) is a statistical relationship, across a model ensemble, between a measurable aspect of the present day climate (the predictor) and an aspect of future projected climate change (the predictand). If such a relationship is robust and understood, it may provide constrained projections for the real world. Here, Coupled Model Intercomparison Project 6 (CMIP6) models are used to revisit several ECs that were proposed in prior model intercomparisons with two aims: (1) to assess whether these ECs survive the partial out-of-sample test of CMIP6 and (2) to more rigorously quantify the constrained projected change than previous studies. To achieve the latter, methods are proposed whereby uncertainties can be appropriately accounted for, including the influence of internal variability, uncertainty on the linear relationship, and the uncertainty associated with model structural differences, aside from those described by the EC. Both least squares regression and a Bayesian Hierarchical Model are used. Three ECs are assessed: (a) the relationship between Southern Hemisphere jet latitude and projected jet shift, which is found to be a robust and quantitatively useful constraint on future projections; (b) the relationship between stationary wave amplitude in the Pacific-North American sector and meridional wind changes over North America (with extensions to hydroclimate), which is found to be robust but improvements in the predictor in CMIP6 result in it no longer substantially constrains projected change in either circulation or hydroclimate; and (c) the relationship between ENSO teleconnections to California and California precipitation change, which does not appear to be robust when using historical ENSO teleconnections as the predictor.
影响因子：
30.7
作者：
Deser, C.;Lehner, F.;Ting, M.
通讯作者：
Ting, M.