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A baroclinic atmosphere without baroclinic waves -A new approach to low-frequency variability

没有斜压波的斜压大气——低频变化的新方法

基本信息

批准号：
12640422
负责人：
ITOH Hisanori
金额：
$ 2.3万
依托单位：
Kyushu University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2002
项目状态：
已结题

项目摘要

The most difficult thing in understanding the mechanism of low-frequency variability (LFV) is the interaction with high-frequency variability (HFV). Therefore, if we can obtain "pure" LFV without interacting with HFV, it greatly helps understand the mechanism. Then, we first construct the atmospheric general circulation model to generate "pure" LFV, using a time filter method.The output by this model is compared with that of the control experiment which is carried out without using a time filter method. The standard deviation of the "pure" LFV shows that the values of the maxima in both the Pacific and the Atlantic are weaker than those in the control experiment. Also, the relationship between the LFV in the Pacific and that in the Atlantic is examined, indicating that the "pure" LFV in the Pacific and that in the Atlantic are coherent. This is contrast to the fact that they are not coherent in the control experiment.We also made a data analysis about the interaction between LFV and HFV. First of all, we show that the Arctic Oscillation is apparent, which is falsely extracted from two independent oscillations, the NAG (North Atlantic Oscillation) and the PNA (Pacific/North American Oscillation), due to a characteristic of the analysis method. Therefore, we treat the NAO and PNA as basic LFVs. As a result, it is found that HFV effectively interact with the NAO and PNA, maintaining these LFVs.

理解低频变异性（LFV）机制中最困难的事情是与高频变异性（HFV）的相互作用。因此，如果我们能够获得“纯”LFV而不与HFV相互作用，将极大地有助于理解其机制。然后，我们首先使用时间滤波方法构建大气环流模型来生成“纯”LFV。将该模型的输出与不使用时间滤波方法进行的控制实验的输出进行比较。 “纯”LFV 的标准差表明，太平洋和大西洋的最大值均弱于对照实验中的最大值。此外，还检查了太平洋和大西洋的 LFV 之间的关系，表明太平洋和大西洋的“纯”LFV 是一致的。这与对照实验中它们不相干的事实形成鲜明对比。我们还对LFV和HFV之间的相互作用进行了数据分析。首先，我们表明北极涛动是明显的，由于分析方法的特点，它是从两个独立的涛动NAG（北大西洋涛动）和PNA（太平洋/北美涛动）中错误地提取出来的。因此，我们将 NAO 和 PNA 视为基本 LFV。结果发现，HFV 有效地与 NAO 和 PNA 相互作用，维持这些 LFV。