Tropical Atlantic influence on Pacific variability and mean state in the twentieth century in observations and CMIP5
Tropical Atlantic influence on Pacific variability and mean state in the twentieth century in observations and CMIP5
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DOI：
10.1007/s00382-014-2228-z
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发表时间：
2015-02-01
期刊：
影响因子：
4.6
通讯作者：
Gohar, A.
中科院分区：
文献类型：
--
作者：
Kucharski, F.;Syed, F. S.;Gohar, A.
本文研究了20世纪热带大西洋对热带太平洋年际变化和平均状态的影响。结果表明，观测数据集显示热带大西洋对热带太平洋海面温度具有显着的时滞影响，如果大西洋领先约 10 个月，则导致热带大西洋和东太平洋之间存在反相关性。该结果在不同的海面温度重建中都是稳健的。当太平洋领先时，热带大西洋和东太平洋之间不存在强相关性，尽管近几十年来两个盆地之间的正相关性更为占主导地位。对热带大西洋表面压力响应的分析表明，大气桥和沃克环流的变化可能是遥相关的触发因素，这一结果与近几十年来的最新观测和建模结果一致。分析的 45 个世界气候研究计划耦合模型比对项目第 5 阶段 (CMIP5) 模型中的 30 个模型显示，个别热带大西洋暖事件和冷事件与时滞东太平洋海面温度之间存在统计上显着的反相关性。 45 个分析模型中有 16 个满足与观测结果类似的热带大西洋和太平洋之间更严格的超前滞后相关性标准。大气桥机制似乎在选定的 CMIP5 模型中也有效。我们已经确定几乎所有模型中都存在热带大西洋暖偏差，作为热带大西洋和太平洋之间整体弱时滞遥相关的潜在候选者之一，但其他平均状态偏差也很重要。在选定的模型中，与全球海面温度平均值相比，热带大西洋的更强烈变暖与热带太平洋的拉尼娜式平均状态变化有关。然而，这些模型的集合平均值仍然显示出微弱的厄尔尼诺趋势，这与与全球平均值和观测结果相比相对较弱的大西洋变暖有关。
This paper investigates the influence of the tropical Atlantic on the tropical Pacific interannual variability and mean state in the twentieth century. It is demonstrated that observational datasets show a significant time-delayed impact of the tropical Atlantic on tropical Pacific sea surface temperatures, leading to an anticorrelation between the tropical Atlantic and the eastern Pacific if the Atlantic is leading by about 10 months. This result is robust across different sea surface temperature reconstructions. There is no robust correlation between the tropical Atlantic and the eastern Pacific when the Pacific is leading, although in recent decades a positive correlation between the two basins is more dominant. An analysis of the surface pressure response to the tropical Atlantic indicates an atmospheric bridge and a modification of the Walker circulation as the likely trigger for the teleconnection, and this result is consistent with recent observational and modelling results for the recent decades. 30 out of the analyzed 45 World Climate Research Program's Coupled Model Intercomparison Project Phase 5 (CMIP5) models show statistically significant anticorrelations between individual tropical Atantic warm and cold events and the time-lagged eastern Pacific sea surface temperatues. 16 out of the 45 analyzed models fulfill the more stringent criterion of lead-lag correlations between the tropical Atlantic and Pacific similar to the observations. The atmospheric bridge mechanism seems also valid in the selected CMIP5 models. We have identified the tropical Atlantic warm bias present in nearly all models as one potential candidate for the overall weak time-delayed teleconnection between the tropical Atlantic and the Pacific, but also other mean state biases are important. In the selected models a stronger warming of the tropical Atlantic Ocean compared to the global sea surface temperature mean is associated with a La Nina-like mean state change in the tropical Pacific. However, the ensemble mean of these models still shows a weakly El Nino-like trend, which is associated with a relatively weak Atlantic warming compared to the global mean and the observations.