Slowing of the Atlantic meridional overturning circulation: A climate model perspective
Slowing of the Atlantic meridional overturning circulation: A climate model perspective
复制标题
大西洋经向翻转环流减慢：气候模型视角
DOI：
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发表时间：
2007
期刊：
影响因子：
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通讯作者：
R. Wood
中科院分区：
文献类型：
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作者：
Y. Searl;H. Banks;S. Stark;R. Wood
对五个跨大西洋水文剖面的分析表明，与20世纪50年代末相比，世纪初的年平均大西洋纬向翻转环流减弱了30%。我们研究模拟大西洋纬向翻转的气候模式HadCM3。在控制实验和20世纪世纪的模拟中，在观测的时间尺度上，翻转没有明显的趋势，年平均翻转变化30%是非常罕见的。我们使用HadCM3来突出与用于从五个观测值获得年平均翻转的方法相关的不确定性。假设水文剖面代表各自的年份，通过地转从密度推断流场，并使用恒定的埃克曼和墨西哥湾流运输，所有的重建倾覆的平均值和变异性都引入了不确定性。使用月水文场而不是年平均场增加了估计的模式纬向翻转环流的变异性。需要对倾覆情况进行持续监测，以便更好地了解年际和季节变化，并进行探测和归因研究。
Analyses of five transatlantic hydrographic sections suggest that the annual average Atlantic meridional overturning circulation was 30% weaker at the beginning of the 21st century compared to the late 1950s. We examine the simulation of the Atlantic meridional overturning in the climate model HadCM3. In both the control experiment and simulations of the 20th century, there is no significant trend in the overturning on the timescales of the observations and a change of 30% in the annual average overturning is very unusual. We use HadCM3 to highlight uncertainties associated with the method used to derive annual average overturning from the five observations. Assuming hydrographic sections to be representative of their respective years, inferring the flow field from density via geostrophy and using constant Ekman and Gulf Stream transport, all introduce uncertainties in both the mean and variability of the reconstructed overturning. Using monthly hydrographic fields rather than annual mean fields increases the variability of the estimated model meridional overturning circulation. Continuous monitoring of the overturning is needed to enable the interannual and seasonal variability to be understood better and to allow detection and attribution studies.