Causality of the Drought in the Southwestern United States Based on Observations
Causality of the Drought in the Southwestern United States Based on Observations
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DOI：
10.1175/jcli-d-16-0601.1
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发表时间：
2017-05
影响因子：
4.9
通讯作者：
Feng Zhang;Yadong Lei;Q. Yu;K. Fraedrich;H. Iwabuchi
中科院分区：
文献类型：
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作者：
Feng Zhang;Yadong Lei;Q. Yu;K. Fraedrich;H. Iwabuchi
摘要：利用慢特征分析从美国西南部（1895-2015）降水月平均距平时间序列中提取驱动力。对导出的驱动力进行小波分析后，四种主要光谱尺度通过了 95% 置信度测试。进一步的谐波分析表明，只有两个基频在谱域中占主导地位。这些频率代表太平洋年代际振荡 (PDO) 和太阳活动对美国西南部降水的影响。此外，太阳活动对美国西南部近120年降水的影响比PDO更大。通过将干旱趋势与两个基本频率进行比较发现，1900年代和21世纪的干旱均受到PDO和太阳活动的影响，而1950年代至1970年代的干旱主要受太阳活动的影响。
AbstractSlow feature analysis is used to extract driving forces from the monthly mean anomaly time series of the precipitation in the southwestern United States (1895–2015). Four major spectral scales pass the 95% confidence test after wavelet analysis of the derived driving forces. Further harmonic analysis indicates that only two fundamental frequencies are dominant in the spectral domain. The frequencies represent the influence of the Pacific decadal oscillation (PDO) and solar activity on the precipitation from the southwestern United States. In addition, solar activity has exerted a greater effect than the PDO on the precipitation in the southwestern United States over the past 120 years. By comparing the trend of droughts with the two fundamental frequencies, it is found that both the droughts in the 1900s and in the twenty-first century were affected by the PDO and solar activity, whereas the droughts from the 1950s to the 1970s were mainly affected by solar activity.