Intraseasonal Canadian Winter Temperature Responses to Interannual and Interdecadal Pacific SST Modulations

The influence of the modal structures of the El Nino-Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO) on the wintertime intraseasonal temperatures and temperature extremes over Canada has been analyzed for the 1900-2008 period. Results demonstrate that intraseasonal temperature variability (longer than 11 days) dominates with a high degree of persistence in western Canada, whereas synoptic-scale variability (shorter than 11 days) prevails in eastern Canada. The PDO has been found to exert a significant modulating effect on ENSO-related intraseasonal temperature impacts in western Canada. In eastern Canada, temperature anomalies are generally weaker, often with ENSO and the PDO producing opposite effects. Spectral analysis shows reddening of the temperature spectra with significant peaks near the 20-day period in western Canada. In contrast, the power of the spectra is weaker with significant peaks occurring near the 13-day period in eastern Canada.