Berlin 2012 – wissenschaftliches Programm
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UP: Fachverband Umweltphysik
UP 9: Poster session
UP 9.11: Poster
Mittwoch, 28. März 2012, 18:30–19:15, Poster F
Estimating the Rate and Intensity of Precipitation Events with regard to Scaling Behavior of a Gamma Process — •Jan Micha Steinhäuser — University of Oldenburg, Germany
The gamma distribution is comparatively well-suited for the description of the amount of rainfall occurring daily and monthly. Thus, it is possible to simulate the cumulative rainfall by a gamma process. Doing so, the mean and the variance of rainfall should show a linear scaling behavior with regard to the length of observation time. In Germany this linear scaling behavior is observable for timescales longer than approx. 20 days. It is possible to construct this gamma process with a Poisson Process on R2. Then, a factorization into two independent processes allows describing the temporal occurrence of rainfall events and the intensity of the individual events separately.
Using this method, it is now possible to show how rainfall events that last longer than the observation interval distort the statistics of rainfall rate and intensity, as long-lasting events are split up and counted several times. This interpretation allows explaining how stochastic precipitation models based on measurements that are to short-period compared to the duration of rainfall events (e.g. daily) overestimate the rate and underestimate the intensities of rainfall events.
As the use of gamma processes suffers from a lack of physical justification and cannot be used to explain scaling properties precisely, further options of modeling the intensities of rainfall events are discussed.