| Summary: | Teleconnections among the central, east equatorial Pacific, the Pacific/North American (PNA) pattern, and Southern Oscillation (SO) and monthly precipitation, monthly temperature, and spring wheat yields in Saskatchewan are examined. When sea surface temperatures in the central equatorial Pacific are warmer than the air temperatures (strong El Niño) there is an upward flux of water vapour into the atmosphere, convection, heat released by condensation, a strengthening of the westerlies and a vitalization of the Hadley circulation. When sea surface temperatures are colder than the air temperatures (strong La Niña) in the central equatorial Pacific it produces the opposite influence on atmospheric processes. Composite analysis reveals that El Niño and La Niña are the primary modulators of the Pacific/North American pattern and movement of surface cyclones across the western continent. Correlation and composite analyses indicate that between 1950 and 1998 warmer than normal sea surface temperatures in the central and east equatorial Pacific during the winter and early spring (El Niño) are associated with cooler and wetter conditions during the May through July period in Saskatchewan and higher wheat yields. Conversely cooler than normal sea surface temperatures in the central and east equatorial Pacific during the winter and early spring (La Niña) are associated with hotter and drier conditions during the May through July period in Saskatchewan and lower wheat yields. The relationship appears to be strongest for the Brown soil zone and weakest for the Black soil zone in Saskatchewan.
|
|---|
