are many different and rather confusing definitions of extreme event in
weather and climate research.
Much current interest is motivated by the high-impacts caused by such
events and how such events
are likely to evolve in the future under climate change. However, to
develop confidence in such studies,
it is necessary to develop deeper physical and statistical
understanding of how such events arise. Rather than focus on impacts, this talk will
present taxonomy of extreme weather and climate events
based on fundamental understanding of key underlying physical
processes. Extreme events arise by
several different dynamical processes such as: *Fast
growth caused by unstable positive feedback (e.g. baroclinic storms,
convective precipitation, etc.)
of an event into a new spatial region or time period (e.g. transition
of a tropical cyclone into mid-latitudes)
of several non-rare events (e.g. freak waves)
in space/time (e.g. precipitation totals, enstrophy).
of weather conditions leading to a climate extreme (e.g. drought)
of weather events (e.g. unusually stormy wet season).
unknown processes related to natural variability that are perhaps best
described as random variations.
Extreme events are therefore able to provide unique
insights into these processes in both the real world and
in numerical model simulations. Examples of some of these processes
will be given together with a discussion
of how to statistically diagnose such processes.