Insights from a refined decomposition of cloud feedbacks
Insights from a refined decomposition of cloud feedbacks
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DOI：
10.1002/2016gl069917
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发表时间：
2016-09
影响因子：
5.2
通讯作者：
M. Zelinka;Chen Zhou;S. Klein
中科院分区：
文献类型：
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作者：
M. Zelinka;Chen Zhou;S. Klein
将云反馈分解为由于几个总云属性的变化而产生的组件，可以对其物理原因提供有价值的见解。在这里，我们提出了一个细化的分解，分别考虑自由对流层和低云属性的变化，更好地连接反馈到个人的管理过程，并避免在常用的分解中存在的歧义。它揭示了三个净云反馈分量是鲁棒非零的：正反馈从增加对流层云的高度和减少低云覆盖和负反馈从增加低云光学厚度。低云量反馈是净云反馈中传播的主要贡献者，但其与其他分量的非线性关系抑制了总体传播。集合平均自由对流层云高度反馈大约是标准云高度反馈的60%，因为它避免了低云减少中的混叠。从充分理解和稳健的模拟反馈的“零假设”的气候敏感性的影响进行了讨论。
Decomposing cloud feedback into components due to changes in several gross cloud properties provides valuable insights into its physical causes. Here we present a refined decomposition that separately considers changes in free tropospheric and low cloud properties, better connecting feedbacks to individual governing processes and avoiding ambiguities present in a commonly used decomposition. It reveals that three net cloud feedback components are robustly nonzero: positive feedbacks from increasing free tropospheric cloud altitude and decreasing low cloud cover and a negative feedback from increasing low cloud optical depth. Low cloud amount feedback is the dominant contributor to spread in net cloud feedback but its anticorrelation with other components damps overall spread. The ensemble mean free tropospheric cloud altitude feedback is roughly 60% as large as the standard cloud altitude feedback because it avoids aliasing in low cloud reductions. Implications for the “null hypothesis” climate sensitivity from well‐understood and robustly simulated feedbacks are discussed.