Climate drift in an ocean model coupled to a simple, perfectly matched atmosphere
Climate drift in an ocean model coupled to a simple, perfectly matched atmosphere
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海洋模型中的气候漂移与简单、完美匹配的大气相结合
DOI：
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发表时间：
1995
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通讯作者：
S. Rahmstorf
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作者：
S. Rahmstorf
一个非常简单的弥漫性能量平衡大气与GFDL海洋环流模式耦合。这为分析耦合后海洋模式中的气候漂移提供了一个有用的工具，并可用于评估各种最小化这种漂移的方案。在这里报告的实验中，大气是这样构造的，它在耦合时刻为海洋模型提供了与自转期间相同的通量。因此，该实验相当于耦合一个完全通量修正的大气模式，并用于研究海洋模式在这些条件下的响应。尽管大气是稳定的、被动的、通量修正的，但海洋模式在耦合后会漂移到一个新的平衡状态。这种转变大约需要2000年；新状态的特征是不同位置的深对流及其引起的高纬海温和全球深温的变化。这种转变的机制是在新的反馈下，耦合后海洋对流模式的不稳定性。在完全耦合的gcm中，耦合激波可能触发海洋模式的类似状态转变。如果是这样的话，这种转变将污染气候情景实验的结果，并且它将解释尽管使用了通量修正，但在耦合模式中观测到的部分残余漂移。
A very simple, diffusive energy balance atmosphere is coupled to the GFDL ocean circulation model. This provides a useful tool for analyzing climate drift in the ocean model after coupling, and may be used to assess various schemes for minimizing such drift. In the experiment reported here, the atmosphere is constructed in such a way that it provides the ocean model at the moment of coupling with the same fluxes as during spinup. The experiment is therefore equivalent to coupling a perfectly flux-corrected atmosphere model, and is used to investigate the response of the ocean model under these conditions. In spite of the steady, passive, flux-corrected atmosphere, the ocean model drifts to a new equilibrium state after coupling. The transition takes about 2000 years; the new state is characterized by different sites of deep convection and resulting changes in high-latitude SST and global deep temperatures. The mechanism for the transition is an instability of the oceanic convection patterns under the new feedback, felt after coupling. A similar state transition of the ocean model may be triggered by the coupling shock in fully coupled GCMs. If this is so, the transition would contaminate the results of climate scenario experiments, and it would explain part of the residual drift observed in coupled models in spite of the use of flux corrections.