Myles Allan, Constraints for Probabilistic Forecasts Myles Allan ...

Richard Chandler, Rainfall Simulation Using Generalised Linear Models
Richard Chandler
Department of Statistical Science, University College London, United Kingdom
and
Chi Yang
We consider the problem of simulating sequences of daily rainfall at a network of sites, in such
a way as to reproduce a variety of properties realistically over a range of spatial scales. The
properties of interest will vary between applications, but typically will include some measures
of 'extreme' rainfall in addition to means, variances, proportions of wet days and
autocorrelation structure. Our approach is to fit a Generalized Linear Model (GLM) to
raingauge data and, with appropriate incorporation of inter-site dependence structure, to use the
GLM to generate simulated sequences. We illustrate the methodology using a dataset from
southern England, and show that the GLM is able to reproduce many properties at spatial
scales ranging from a single site to 2000km2 (the limit of the available data). Having
established this, we explore the potential for using the GLM to generate future rainfall
scenarios conditioned on climate model outputs.