Multi-decadal thermohaline variability in an ocean–atmosphere general circulation model
Multi-decadal thermohaline variability in an ocean–atmosphere general circulation model
复制标题
海洋大气环流模型中的多年代际温盐变化
DOI：
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发表时间：
2004
期刊：
影响因子：
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通讯作者：
C. Rooth
中科院分区：
文献类型：
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作者：
W. Cheng;R. Bleck;C. Rooth
摘要
利用一个世纪尺度的近全球海气耦合模式，研究了大西洋温盐环流（THC）的年代际变化。耦合和两个补充的海洋实验之间的差异表明，这种变化的一个重要组成部分是由海洋和大气的集体行为，特别是在海气热交换的形式，或子每月随机噪声耦合系统中存在的控制。可能的物理机制引起的模式THC的变化进行了讨论。与THC变率相关的SST异常类似于从观测数据中提取的年代际SST模式，以及与GFDL耦合模式中的50-60年THC变率相关的模式。在每一种情况下，变暖整个亚极地北大西洋，但集中沿着墨西哥湾流及其延伸时，THC是强的指示。与此同时，在较暖的海洋上，地面气温有正的异常，最强的信号位于最暖SST异常的下风处，并侵入欧亚大陆西部。除了热响应外，还有大气流型的变化。更具体地说，一个异常的偏北风的拉布拉多海时，THC是强于正常的，这表明在温盐扰动结构的大气强迫的本地首要地位。
Abstract
A century scale integration of a near-global atmosphere–ocean model is used to study the multi-decadal variability of the thermohaline circulation (THC) in the Atlantic. The differences between the coupled and two supplementary ocean-only experiments suggest that a significant component of this variability is controlled by either a collective behavior of the ocean and the atmosphere, particularly in the form of air-sea heat exchange, or sub-monthly random noise present in the coupled system. Possible physical mechanisms giving rise to the mode of this THC variability are discussed. The SST anomaly associated with the THC variability resembles an interdecadal SST pattern extracted from observational data, as well as a pattern associated with the 50–60 year THC variability in the GFDL coupled model. In each case, a warming throughout the subpolar North Atlantic but concentrated along the Gulf Stream and its extension is indicated when the THC is strong. Concomitantly, surface air temperature has positive anomalies over the warmer ocean, with the strongest signal located downwind of the warmest SST anomalies and intruding into the western Eurasian Continent. In addition to the thermal response, there are also changes in the atmospheric flow pattern. More specifically, an anomalous northerly wind develops over the Labrador Sea when the THC is stronger than normal, suggesting a local primacy of the atmospheric forcing in the thermohaline perturbation structure.