Canadian precipitation patterns associated with the southern oscillation
- Environment Canada, Downsview, Ontario (Canada)
Precipitation responses over Canada associated with the two extreme phases of the Southern Oscillation (SO), namely El Nino and La Nina are identified. Using the best available precipitation data from 1911 to 1994, both the spatial and temporal behavior of the responses are analyzed from the El Nino/La Nino onset to several seasons afterward. Composite and correlation analyses indicate that precipitation over a large region of southern Canada extending from British Columbia, through the prairies, and into the Great Lakes region is significantly influenced by the SO phenomenon. The results show a distinct pattern of negative (positive) precipitation anomalies in this region during the first winter following the onset of El Nino (La Nina) events. During this same period, significant positive precipitation anomalies occur over the northern prairies and southeastern Northwest Territories in association with El Nino events. Statistical significance of the responses is tested by the Student`s t-test and the Wilcoxon rank-sum test, while field significance is established through the Monte Carlo procedure. All of the significant precipitation anomalies can be explained by the associated upper-atmospheric flow patterns, which during the first winter following the onset of El Nino events resemble the positive (negative) phase of the Pacific-North American (PNA) pattern. Significant correlations between Southern Oscillation index (SOI) values and the observed precipitation anomalies over southern Canada suggest the possibility of developing a long-range forecasting technique for Canadian precipitation based on the occurrence and evolution of the various phases of the SO. 31 refs., 10 figs., 3 tabs.
- OSTI ID:
- 576784
- Journal Information:
- Journal of Climate, Vol. 10, Issue 12; Other Information: PBD: Dec 1997
- Country of Publication:
- United States
- Language:
- English
Similar Records
Seasonal and interannual variability of atmospheric heat sources and moisture sinks as determined from NCEP/NCAR reanalysis: Part II variability associated with ENSO
The influences of Type 1 El Nino and La Nina events on streamflows in the Pacific Southwest of the United States