TITLE:
Spatial Distribution of Cordex Regional Climate Models Biases over West Africa
AUTHORS:
Alioune Badara Sarr, Moctar Camara, Ibrahima Diba
KEYWORDS:
CORDEX, Regional Climate Models, Rainfall
JOURNAL NAME:
International Journal of Geosciences,
Vol.6 No.9,
September
24,
2015
ABSTRACT: The objective of this work
is to analyze the spatial distribution of biases of nine (9) regional climate
models (RCMs) and their ensemble average used under the framework of
COordinated Regional climate Downscaling EXperiment (CORDEX) project over West
Africa during the summer period. We assessed the ability of RCMs to represent
adequately West African summer rainfall by analyzing some statistical
parameters such as the relative bias, the standard deviation, the root mean
square error (RMSE) and the correlation coefficient between observation data
(GPCP used as reference) and regional climate models outputs. We first analyzed
the relative bias between GPCP climatology and the other available observed
data (CRU, CMAP, UDEL, GPCC, TRMM and their ensemble mean). This analysis
highlights the big uncertainty on the quality of these observed rainfall data
over West Africa which may be largely due to the rarity ofin situmeasurement data over this region. The
statistical analysis with respect to GPCP rainfall shows the presence of large
relative bias values over most part of West Africa for engaged RCMs. However
their ensemble mean outperforms individual RCMs by exhibiting the weakest
relative change. The RMSE values are weak over West Africa except over and off
the Guinea highlands for RCMs and the Era-interim reanalysis. The spatial
distribution of the coefficient of correlation between the observation data and
RCMs shows that all models (except HIRHAM) present positive values over the
Northern Sahel and the Gulf of Guinea. The model of the DMI exhibits the
weakest values of correlation coefficient. This study shows that RCMs simulate
West African climate in a satisfactory way despite the fact that they exhibit
systematic biases.