The tenth IMSC, Beijing, China, 2007 - International Meetings on ...

different time periods. <strong>The</strong>re are negative temperature trends from 1945 to 1970; all other time
periods show positive trends. In addition, several abrupt changes in temperature were
detected respectively in the year 1937, 1913, 1986 and 1949.
An Automated Synoptic Weather Typing and Its Applications to Climate Change Impact
Analyses
Speaker: Chad Shouquan Cheng
Chad Shouquan Cheng
Meteorological Service of Canada Branch, Environment Canada
cheng@ec.gc.ca
<strong>The</strong> synoptic weather typing approach has become popular in evaluating the impact of
climate on a variety of environmental problems. One of the reasons is its ability to categorize a
complex set of meteorological variables as a coherent index and to facilitate to link with
high-impact weather analyses. In a series of studies, an automated synoptic weather typing
was developed using principal components analysis, average linkage clustering procedure,
and discriminant function analysis to classify daily weather types. Meteorological data used in
the weather typing usually include hourly/six-hourly surface observations of air temperature,
dew point temperature, sea-level air pressure, total cloud cover, and west-east and
south-north wind velocities. <strong>The</strong> weather typing approach was validated using an independent
dataset (1/4–1/3 of the total years) that was randomly selected.
This talk will focus on development and validation of the synoptic weather typing and its
applications to a variety of high-impact weather analyses, such as freezing rain, heavy rainfall,
high air pollutant levels, and extreme temperature/air pollution-related premature mortality. In
addition, this talk will summarize how the weather typing was applied, using downscaled GCM
climate change scenarios, to project changes in frequency and magnitude of future
high-impact weather events.
Answering questions about empirical downscaling methodologies
Speaker: Bruce Hewitson
Bruce Hewitson
University of Cape Town
hewitson@csag.uct.ac.za
R Wilby
UK Environment Agency
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