Nonnormal Thermohaline Circulation Dynamics in a Coupled Ocean–Atmosphere GCM

Nonnormal Thermohaline Circulation Dynamics in a Coupled Ocean–Atmosphere GCM
复制标题

海洋-大气耦合 GCM 中的非正态温盐环流动力学

DOI：
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
C. Penland
C. Penland
中科院分区：
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文献类型：
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作者：
E. Tziperman;L. Zanna;C. Penland

文献摘要

被引文献

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摘要利用GFDL海气耦合环流模式CM2.1，研究了温盐环流（THC）异常的非正态动力学瞬态放大。构造了北大西洋温盐距平场的经验正交函数（EOFs）约化空间。在假设该缩减空间的动力学是线性的情况下，然后评估系统的传播子并分析THC异常的瞬时增长。虽然线性动力学是稳定的，这样，任何初始扰动最终衰减，非正常的影响被发现，导致在一个显着的瞬态增长的温度，盐度，和THC异常。这些异常的增长时间尺度是5和10年之间，提供了一个估计的预测时间的北大西洋THC在这个模型中。有迹象表明，这些结果仅仅是一个下限的THC动力学在目前耦合GCM的非正态性。这似乎...
Abstract Using the GFDL coupled atmosphere–ocean general circulation model CM2.1, the transient amplification of thermohaline circulation (THC) anomalies due to its nonnormal dynamics is studied. A reduced space based on empirical orthogonal functions (EOFs) of temperature and salinity anomaly fields in the North Atlantic is constructed. Under the assumption that the dynamics of this reduced space is linear, the propagator of the system is then evaluated and the transient growth of THC anomalies analyzed. Although the linear dynamics are stable, such that any initial perturbation eventually decays, nonnormal effects are found to result in a significant transient growth of temperature, salinity, and THC anomalies. The growth time scale for these anomalies is between 5 and 10 yr, providing an estimate of the predictability time of the North Atlantic THC in this model. There are indications that these results are merely a lower bound on the nonnormality of THC dynamics in the present coupled GCM. This seems ...