Wednesday, 17 January 2001: 3:30 PM
The association between trends in Canadian temperature and changes in the
planetary circulation over the Northern Hemisphere has been investigated.
A principal component analysis was performed on the sea level pressure of
the Northern Hemisphere, and the first 6 principal components were retained
as predictors. Multiple linear regressions were then established between
gridded temperature anomalies and the predictors to reconstruct temperature
anomalies based on a cross-validation framework. Trends were finally computed
for the original and reconstructed temperatures. The results suggest that
50-80% of observed trends in annual, winter, and spring mean temperatures and a
considerable portion of trends in summer and autumn temperatures can be
associated with the variations of the planetary circulation. They also indicate
that the circulation patterns that are linked to Arctic Oscillation and
Pacific Decadal Oscillation mainly influence temperature trends over northeast
and southwest, respectively.
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