High-resolution rainfall variability simulated by the WRF RCM: application to eastern France.
Résumé
The Weather Research and Forecasting (WRF)
model, driven laterally by ERA-Interim reanalyses, is used
here to downscale rainfall, at relatively high resolution
(*8 km) over Burgundy (eastern France), during the period
1989–2009. Regional simulations are compared to the
Me´te´o-France Station Network (MFSN; 127 daily raingauge
records), at various temporal scales, including
interannual variability, the annual cycle, and weather types.
Results show that the spatial distribution of WRF-simulated
rainfall climatology is consistent with MFSN observation
data, but WRF tends to overestimate annual rainfall
by *?15 %. At the interannual scale, WRF also performs
very well (r * 0.8), despite almost constant, systematic
overestimation. Only the average annual rainfall cycle is
not accurately reproduced by WRF (r * 0.5), with rainfall
overestimation in spring and summer, when convective
rainfall prevails. During the winter season (October–
March), when stratiform rainfall is prevalent, WRF performs
better. Despite the biases for summertime convective
events, these results suggest that high-resolution WRF
simulations could successfully be used to document present
and future climate variability at a regional scale. Nevertheless,
because of overestimated convective rainfall,
WRF-simulated rainfall should probably not be used
directly to feed impact models, especially during the vegetative
summer period.