A generalised hybrid model to generate point rainfall for a wide range of a
ggregation levels is presented in this paper, The rainfall process is expre
ssed as a product of a binary chain model. which preserves the dry and wet
sequences as well as the mean, and a correlated jitter used to improve the
deficiencies in the second-order properties of the binary chain. Analytical
derivations of the moments of a binary chain are presented. As the jitter
model the exponential of a second-order autoregressive Gaussian process is
selected. Two possible binary chain models are analysed, a non-randomised B
artlett-Lewis model and a Markov chain. Although both binary chain models p
erform equally well, the Bartlett-Lewis model is preferred for reasons of p
arameter parsimony. (C) 1999 Elsevier Science B.V. All rights reserved.