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.

理解低频可变性（LFV）机制的最困难的事情是与高频可变性（HFV）的相互作用。因此，如果我们可以在不与HFV相互作用的情况下获得“纯” LFV，它极大地有助于理解机制。然后，我们首先使用时间过滤器方法构建大气通用循环模型，以生成“纯” LFV。该模型的输出与无需使用时滤波器方法进行的控制实验的输出与对照实验进行了比较。 “纯” LFV的标准偏差表明，在太平洋和大西洋中，最大值的值都比对照实验中的值弱。同样，对太平洋的LFV与大西洋中的LFV之间的关系进行了检查，表明太平洋和大西洋中的“纯” LFV是连贯的。这与他们在控制实验中不是连贯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，由于分析方法的特征，北极振荡是显而易见的，它是从两个独立振荡（北大西洋振荡）和PNA（太平洋/北美振荡）中错误提取的。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，以维持这些LFV。