Intra-El Niño Variability of Surface air Temperature Signals Across Western Canada

Abstract

This paper examines the nature of intra-El Niño variation of surface air temperature (SAT) signals across western Canada by analyzing spatial and temporal variation of linear statistical relationships between various El Niño indices and SAT signals during warm events. Results show that SAT signals are strongly related to a combination of El Niño characteristics: (1) event strength; (2) type and position of forcing; and (3) timing of the El Niño cycle. Strong events encourage the development of positive [negative] SAT signals during winter, and spring [fall] throughout western Canada. Western Pacific surface water temperatures are most critical in defining SAT signals across western Canada during fall and spring. Sea level pressure conditions in the eastern and western tropical Pacific are important during the winter. Summer SAT signals vary independently of El Niño. Characteristics during the ante- and onset phases of El Niño are the most critical in defining the fall (0) and winter (+1) SAT signals; during spring (+1) it is the peak phase that appears most critical. The identification of these relationships may prove useful in forecasting future El Niño-related temperature signals across the study area.