Wavelet analysis of variability in annual Canadian streamflows
Wavelet analysis of variability in annual Canadian streamflows
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DOI：
10.1029/2003wr002667
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发表时间：
2004-03-16
影响因子：
5.4
通讯作者：
Burn, DH
中科院分区：
文献类型：
--
作者：
Coulibaly, P;Burn, DH
小波分析被用来识别和描述在每年的加拿大径流的变化，并深入了解径流和主导模式的气候变率在北方半球之间的动态联系。从加拿大参考水文流域网络（RHBN）中选择的79条河流的平均年径流量应用连续小波变换的结果显示，在20世纪50年代之前和20世纪70年代之后，惊人的气候相关的功能。1911年至1999年的现有观测跨度可用于描述长达12年的变化。尺度平均小波功率谱被用来同时评估79年径流时间序列的年际和空间变异。在2-3年波段和3-6年波段（6-12年波段主要是白色噪声（自1950年以来），不再进一步考虑）中最显著的特征是西部、中部和东部流量年际变化的时间和强度之间的净区别，这表明与区域气候学有关。结果表明，在2-3年波段中，加拿大径流在1950-1999年主要由北美太平洋（PNA）来描述，在1950年以前主要由北方半球环形模态（NAM）来描述，在1970年以后主要由北大西洋涛动（NAO）来描述。同样，在3-6年波段，径流主要由NAO、1950-1999年期间Nino-3区域的海表温度异常（ENSO 3）和PNA以及1950年之前的NAM来描述。此外，遥相关模式和西部，中部和东部的流量之间的强本地相关性也揭示了在2-3和3-6年带与1950年和1970年左右的显着变化。在2-3年和3-6年波段的相关性分析表明，在1950年和1970年左右发生在西部和东部流量的两个变化点的存在。
Wavelet analysis is used to identify and describe variability in annual Canadian streamflows and to gain insights into the dynamical link between the streamflows and the dominant modes of climate variability in the Northern Hemisphere. Results from applying continuous wavelet transform to mean annual streamflows from 79 rivers selected from the Canadian Reference Hydrometric Basin Network (RHBN) reveal striking climate-related features before the 1950s and after the 1970s. The span of available observations, 1911-1999, allows for depicting variance for periods up to 12 years. Scale-averaged wavelet power spectra are used to simultaneously assess the interannual and spatial variability in 79 annual streamflow time series. The most striking feature, in the 2-3 year band and in the 3-6 year band (the 6-12 year band is dominated by white noise ( since 1950) and is not considered further) is a net distinction between the timing and intensity of the interannual variability in western, central, and eastern streamflows, which is shown to be linked to the regional climatology. It is found that for the 2-3 year band, the Canadian streamflows are depicted mainly by the Pacific North America (PNA) during 1950-1999, and the Northern Hemisphere Annular Mode (NAM) only prior to 1950, and the North Atlantic Oscillation (NAO) after 1970. Similarly, in the 3-6 year band, the streamflows are depicted mostly by the NAO, the sea surface temperature anomalies over the Nino-3 region (ENSO3) and the PNA during the period 1950-1999, and the NAM prior to 1950. Furthermore, strong local correlations between teleconnection patterns and western, central, and eastern streamflows are also revealed in both the 2-3 and 3-6 year bands with striking changes around 1950 and 1970. The correlation analysis in the 2-3 year and 3-6 year bands revealed the presence of two change points in the west and east streamflows occurring around 1950 and 1970.