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

低频变异性（LFV）与高频变异性（HFV）的相互作用是理解LFV机制的最大难点。因此，如果我们能够获得“纯”LFV而不与HFV相互作用，这将极大地有助于理解其机制。然后，我们首先建立大气环流模式，使用时间滤波方法产生“纯”LFV，并将此模式的输出与未使用时间滤波方法的对照实验的输出进行比较。“纯”LFV的标准差表明，在太平洋和大西洋的最大值是弱于那些在控制实验。此外，在太平洋和大西洋的LFV之间的关系进行了检查，表明在太平洋和大西洋的“纯”LFV是一致的。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，这是错误的提取两个独立的振荡，NAG（北大西洋涛动）和PNA（太平洋/北美涛动），由于分析方法的特点。因此，我们将NAO和PNA视为基本LFV。结果发现，HFV与NAO和PNA有效地相互作用，维持这些LFV。

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.