Abstract. Stochastic weather simulation models are commonly employed in water
resources management, agricultural applications, forest management,
transportation management, and recreational activities. Stochastic
simulation of multisite precipitation occurrence is a challenge because of
its intermittent characteristics as well as spatial and temporal
cross-correlation. This study proposes a novel simulation method for
multisite precipitation occurrence employing a nonparametric technique, the
discrete version of the k-nearest neighbor resampling (KNNR), and couples
it with a genetic algorithm (GA). Its modification for the study of climatic
change adaptation is also tested. The datasets simulated from both the discrete KNNR
(DKNNR) model and an existing traditional model were evaluated using a number of
statistics, such as occurrence and transition probabilities, as well as
temporal and spatial cross-correlations. Results showed that the proposed
DKNNR model with GA-simulated multisite precipitation occurrence preserved
the lagged cross-correlation between sites, while the existing conventional
model was not able to reproduce lagged cross-correlation between stations, so
long stochastic simulation was required. Also, the GA mixing process
provided a number of new patterns that were different from observations,
which was not feasible with the sole DKNNR model. When climate change was
considered, the model performed satisfactorily, but further improvement is
required to more accurately simulate specific variations of the occurrence
probability.