A new way of quantifying GCM water vapour feedback
A new way of quantifying GCM water vapour feedback
复制标题
量化 GCM 水蒸气反馈的新方法
DOI：
10.1007/s00382-012-1294-3
复制
发表时间：
2012
期刊：
影响因子：
4.6
通讯作者：
Ingram W
中科院分区：
文献类型：
--
作者：
Ingram W
水汽反馈可能是对气候敏感性的最大贡献，也是对气候不确定性的第二大贡献，因为大气环流模型（GCM，我们拥有的物理上最详细的气候模型）之间存在分歧。然而，一直没有量化的，它允许这些差异归因于物理的目的是限制真正的价值。本文提出了一种新的非云长波对气候变化响应的分解方法，它避免了传统分解方法存在的问题，并将其应用于一组4个GCM。基本的物理差异是温度用作垂直坐标，相对湿度用作湿度变量。在这个框架中，不同的GCM的反馈看起来更相似，这与我们的理解一致，即它们的水蒸气响应在物理上非常相似。此外，在全局平均值中，所有反馈分量具有相同的符号，允许我们方便地将整体响应部分地归因于（例如，约60%来自“部分泊松”分量）。传统分解中不同反馈成分之间的系统抵消消失了，所以现在反馈成分的差异实际上导致了气候敏感性的差异，而这些GCM之间在非云LW部分的差异可以追溯到公式，平均气候和气候变化响应的差异。物理效应，如那些由于在LW的辐射传输公式的变化变得可见。变暖分布的差异不再主导大气环流模式的比较。最大的分量只取决于当地的GCM的平均气候，所以它原则上可以计算为真实的世界和验证。然而，依赖于气候变化响应的组成部分可能是大气环流模型之间变化的主要原因。简单地改变湿度变量在传统的击穿的效果也被检查。它给出了一些改进--取消的损失使得传统的分解对理解GCM的气候敏感性之间的差异毫无用处--但不是与平均气候的联系。
The water vapour feedback probably makes the largest contribution to climate sensitivity, and the second-largest contribution to its uncertainty, in the sense of disagreement between General Circulation Models (GCMs, the most physically detailed models of climate we have). Yet there has been no quantification of it which allows these differences to be attributed physically with the aim of constraining the true value. This paper develops a new breakdown of the non-cloud LW (longwave) response to climate change, which avoids the problems of the conventional breakdown, and applies it to a set of 4 GCMs. The basic physical differences are that temperature is used as the vertical coordinate, and relative humidity as the humidity variable. In this framework the different GCMs’ feedbacks look more alike, consistent with our understanding that their water vapour responses are physically very similar. Also, in the global mean all the feedback components have the same sign, allowing us to conveniently attribute the overall response fractionally (e.g. about 60% from the “partly-Simpsonian” component). The systematic cancellation between different feedback components in the conventional breakdown is lost, so now a difference in a feedback component actually contributes to a difference in climate sensitivity, and the differences between these GCMs in the non-cloud LW part of this can be traced to differences in formulation, mean climate and climate change response. Physical effects such as those due to variations in the formulation of LW radiative transfer become visible. Differences in the distribution of warming no longer dominate comparison of GCMs. The largest component depends locally only on the GCM’s mean climate, so it can in principle be calculated for the real world and validated. However, components dependent on the climate change response probably account for most of the variation between GCMs. The effect of simply changing the humidity variable in the conventional breakdown is also examined. It gives some of this improvement—the loss of the cancellations that leave the conventional breakdown of no use to understand differences between GCMs’ climate sensitivities—but not the link to mean climate.
气候变化的水蒸气反馈的一个非常简单的模型
影响因子：
8.9
作者：
Ingram W
通讯作者：
Ingram W
影响因子：
4.6
作者：
Ingram W
通讯作者：
Ingram W
影响因子：
4.6
作者：
R. Colman;J. Fraser;L. Rotstayn
通讯作者：
L. Rotstayn