Climate feedbacks determined using radiative kernels in a multi-thousand member ensemble of AOGCMs
Climate feedbacks determined using radiative kernels in a multi-thousand member ensemble of AOGCMs
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DOI：
10.1007/s00382-009-0661-1
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发表时间：
2010-12
期刊：
影响因子：
4.6
通讯作者：
B. Sanderson;K. M. Shell;W. Ingram
中科院分区：
文献类型：
--
作者：
B. Sanderson;K. M. Shell;W. Ingram
使用辐射核函数诊断气候反馈是最近的发展，可应用于现有的气候变化模拟。我们应用辐射核技术的瞬变模拟从一个多千元扰动物理系综耦合大气-海洋环流模式，比较模型的反馈分布与CMIP-3多GCM系综。虽然晴空长波反馈的扰动物理系综的范围是类似的，在多GCM系综，内核技术低估了净晴空反馈（或辐射强迫）在一些扰动模式显着改变湿度分布。此外，发现全球平均大气直减率反馈和水汽反馈之间的补偿关系在扰动物理系综中成立，但系综中相对湿度分布的巨大差异阻碍了这种补偿在区域尺度上的成立。这两个合奏表现出类似的范围内的全球平均净云反馈的响应，但扰动物理合奏的平均值被转移到更积极的值，使没有扰动模型表现出净负云反馈。扰动物理系综包含较少的模式，具有较强的负短波云反馈和较强的补偿正长波反馈。一个主成分分析，用于确定反馈变化的主导模式显示，扰动物理集合产生非常不同的模式的气候响应的多模式集合，这表明，一个可能不会被用来作为一个模拟的其他在未来响应的不确定性估计。而在多模式集合中，云反馈的一阶变化表现出长波和短波分量之间的补偿，在扰动物理集合中，短波反馈是未补偿的，这可能解释了在扰动模拟中观察到的较大范围的气候敏感性。回归分析表明，控制云的形成，对流强度和冰的下降速度的参数是最显着的改变气候反馈。海洋和硫循环参数的扰动对核技术诊断的大气反馈的影响相对较小。
The use of radiative kernels to diagnose climate feedbacks is a recent development that may be applied to existing climate change simulations. We apply the radiative kernel technique to transient simulations from a multi-thousand member perturbed physics ensemble of coupled atmosphere-ocean general circulation models, comparing distributions of model feedbacks with those taken from the CMIP-3 multi GCM ensemble. Although the range of clear sky longwave feedbacks in the perturbed physics ensemble is similar to that seen in the multi-GCM ensemble, the kernel technique underestimates the net clear-sky feedbacks (or the radiative forcing) in some perturbed models with significantly altered humidity distributions. In addition, the compensating relationship between global mean atmospheric lapse rate feedback and water vapor feedback is found to hold in the perturbed physics ensemble, but large differences in relative humidity distributions in the ensemble prevent the compensation from holding at a regional scale. Both ensembles show a similar range of response of global mean net cloud feedback, but the mean of the perturbed physics ensemble is shifted towards more positive values such that none of the perturbed models exhibit a net negative cloud feedback. The perturbed physics ensemble contains fewer models with strong negative shortwave cloud feedbacks and has stronger compensating positive longwave feedbacks. A principal component analysis used to identify dominant modes of feedback variation reveals that the perturbed physics ensemble produces very different modes of climate response to the multi-model ensemble, suggesting that one may not be used as an analog for the other in estimates of uncertainty in future response. Whereas in the multi-model ensemble, the first order variation in cloud feedbacks shows compensation between longwave and shortwave components, in the perturbed physics ensemble the shortwave feedbacks are uncompensated, possibly explaining the larger range of climate sensitivities observed in the perturbed simulations. Regression analysis suggests that the parameters governing cloud formation, convection strength and ice fall speed are the most significant in altering climate feedbacks. Perturbations of oceanic and sulfur cycle parameters have relatively little effect on the atmospheric feedbacks diagnosed by the kernel technique.