Osborn, T. J. and M. Hulme, 1998: Evaluation of the daily
precipitation characteristics of AMIP atmosphere model simulations over
Europe, International Journal of Climatology,18,505-522.
Evaluating the daily precipitation performance of general circulation
models at a regional scale is beset with two (related) difficulties: a)
ensuring an adequate network of observed daily station data across a region,
and b) establishing 'true' areal means of daily precipitation from these
station data to ensure a like-with-like comparison. These two difficulties
have generally restricted past evaluations of daily model precipitation
to individual grid boxes and to comparisons of model grid-box data with
observed sub-grid-box scale data. In this paper we exploit a dataset of
several dozen daily station time series in western Europe using a new method
for estimating 'true' areal mean daily precipitation
to evaluate the daily precipitation performance in the region of
12 atmospheric general circulation model simulations undertaken as part
of the Atmospheric Model Intercomparison Project. We examine four quantities derived from the simulated
daily precipitation: seasonal mean precipitation, daily standard deviation,
the frequency of raindays and the mean precipitation intensity of those
raindays. We show that simulated winter precipitation tends to be too great,
falls on too many days, but is generally less intense than that observed.
In summer, model results are more variable with some model simulations
yielding statistics quite similar to those observed. Although there is
some uncertainty in these evaluation statistics owing to the effect of
inter-decadal climate variability, there is a weak suggestion of improved
performance with increased spatial resolution. Any systematic effect in
model performance due to different convective parameterisation schemes
is obscured by other confounding factors.