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Modelling the annual cycle of extreme precipitation
Henning Rust

April 10, 2008, 2:30pm
Building 19, Room 4.15 University Potsdam, Campus Neues Palais

The frequency and intensity of precipitation can change significantly
throughout the seasons. Therefore the probability for extreme
precipitation events with dangerous consequences can be very different
in different months of the year. To account for this seasonal
variation, many analyses consider only precipitation for a given
season, e.g., summer or winter, or even for a specific month. In the
presented study, we use a non-stationary generalised extreme value
distribution (GEV) to describe the variable occurrence rate of extreme
precipitation events of 689 gauges across the UK. We show
that the seasonal variation of the location and scale parameters of
the GEV can be well approximated using harmonic functions. Compared to
a monthly resolved extreme value modelling the uncertainty in the GEV
parameter estimation can be significantly reduced. Another reduction
in parameter uncertainty can be achieved by a spatial averaging of the
shape parameter. This allows for a more precise estimation of the
return level of extreme precipitation for a specific month.

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