Wavelet analysis of variability in annual Canadian streamflows

Abstract

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 Niño‐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.

Characterization of the Interannual Variability of Precipitation and Streamflow in Tensift and Ksob Basins (Morocco) and Links with the NAO

“…These characteristics were also reported by other works related to unregulated watersheds [55,[66][67][68], which suggested a climatic origin of such a transient pattern rather than an anthropogenic one. In addition, the External forcing (atmospheric) determines the water inflows and the energy in a watershed as well as their spatial and temporal variability (rain), the climate forcing influence on hydrological response of basin over the time [69].…”

Analyse de l’influence de l’oscillation Arctique sur la variabilité interannuelle des précipitations dans le bassin versant de la rivière Saint-François (Québec, Canada) au moyen de la méthode des corrélations canoniques

“…Cependant, la plupart des travaux consacrés à la partie Nord-Orientale du continent nord américain (le Nord-Est et l'Est du Canada ainsi que le Nord-Est des États-Unis) se sont surtout intéressés à l'analyse de l'influence de ce facteur sur la variabilité interannuelle des débits. Ainsi, au Nord-Est et à l'Est du Canada, les débits de rivières sont négativement corrélés à l'oscillation arctique (ANCTIL et COULIBALY, 2004;COULIBALY et BURN, 2004, 2005DÉRY et WOOD, 2004, 2005KINGSTON et al, 2006) alors que dans la région NordOrientale des États-Unis d'Amérique, les deux variables sont positivement corrélées (KINGSTON et al, 2006). Toutefois, au Québec (au sud du 50°N), la relation entre l'oscillation arctique et les débits est relativement complexe et n'est pas constante dans le temps (ANCTIL et COULIBALY, 2004).…”

Low-frequency variability in Southwestern Canadian stream flow: links with large-scale climate anomalies

“…Moore, 1996;Moore and McKendry, 1996;Woo and Thorne, 2003;Coulibaly and Burn, 2004), none of these studies has explicitly investigated the impacts of the different phases of ENSO, which is necessary to objectively identify seasons during which large-scale climate anomalies may provide potential prediction skills. In addition, interdecadal streamflow variability and its (possible) interaction with the variability at interannual scales have not been explored in any of the previous studies.…”