Planetary albedo in strongly forced climate, as simulated by the CMIP3 models
Planetary albedo in strongly forced climate, as simulated by the CMIP3 models
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CMIP3 模型模拟的强强迫气候下的行星反照率
DOI：
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发表时间：
2011
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影响因子：
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通讯作者：
F. Bender
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作者：
F. Bender
在一个大气环流模式的集合中，全球平均CO2浓度在强CO2强迫下显著降低。在一些模型中，这种正反馈的幅度与CO2强迫本身一样大。由于冰雪覆盖的消退，这些模型在地表对趋势的贡献上一致，但在云的短波辐射效应的贡献上却显示出很大的差异。云的贡献定义为晴空和全天空云的异常之间的差异，表示为ΔCC与模式中的平衡气候敏感性相关（相关系数0.76），表明在高敏感性模式中，云在更大程度上起到增强负晴空云趋势的作用，而在低敏感性模式中，云反而抵消了这一趋势。因此，在更敏感的模型中，总趋势更为负面（相关系数为0.73）。这以一种新的方式说明了云对全球变暖的反应在确定模型中气候敏感性方面的重要性。云的贡献，以云的趋势主要是归因于总的云分数的变化，但云的变化也可能是重要的。
In an ensemble of general circulation models, the global mean albedo significantly decreases in response to strong CO2 forcing. In some of the models, the magnitude of this positive feedback is as large as the CO2 forcing itself. The models agree well on the surface contribution to the trend, due to retreating snow and ice cover, but display large differences when it comes to the contribution from shortwave radiative effects of clouds. The “cloud contribution” defined as the difference between clear-sky and all-sky albedo anomalies and denoted as ΔCC is correlated with equilibrium climate sensitivity in the models (correlation coefficient 0.76), indicating that in high sensitivity models the clouds to a greater extent act to enhance the negative clear-sky albedo trend, whereas in low sensitivity models the clouds rather counteract this trend. As a consequence, the total albedo trend is more negative in more sensitive models (correlation coefficient 0.73). This illustrates in a new way the importance of cloud response to global warming in determining climate sensitivity in models. The cloud contribution to the albedo trend can primarily be ascribed to changes in total cloud fraction, but changes in cloud albedo may also be of importance.