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Precipitation Climatology in an Ensemble of CORDEX-Africa Regional Climate Simulations

Journal: Journal of Climate
Year: 2012   Volume: 25
Initial page: 6057   Last page: 6078
Status: Published
In this status since: 1 Sep 2012
Link to PDF: http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-11-00375.1
DOI: 10.1175/JCLI-D-11-00375.1
Nikulin, G., Jones, C., Samuelsson, P., Giorgi, F., Sylla, M.B., Asrar, G., Büchner, M., Cerezo-Mota, R., Christensen, O.B., Dequè, M., , Hänsler, A., van Meijgaard, E., Sushama, L.

An ensemble of regional climate simulations is analysed to evaluate the ability of ten
regional climate models (RCMs) and their ensemble average to simulate precipitation
over Africa. All RCMs use a similar domain and spatial resolution of ~50km and are
driven by the ERA-Interim reanalysis (1989-2008). They constitute the first set of
simulations in the CORDEX-Africa project. Simulated precipitation is evaluated at a
range of time scales, including seasonal means, annual and diurnal cycles, against a
number of detailed observational datasets.
All RCMs simulate the seasonal mean and annual cycle quite accurately, although
individual models can exhibit significant biases in some sub-regions and seasons. The
multi-model average generally outperforms any individual simulation, showing biases of
similar magnitude to differences across a number of observational data sets. Moreover,
many of the RCMs significantly improve the precipitation climate compared to that from
their boundary condition data set - ERA-Interim. A common problem in the majority of
the RCMs is that precipitation is triggered too early during the diurnal cycle, although a
small subset of models do have a reasonable representation of the phase of the diurnal
cycle. The systematic bias in the diurnal cycle is not improved when the ensemble mean
is considered. Based on this performance analysis, it is assessed that the present set of
RCMs can be used to provide useful information on climate projections over Africa.