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The input and bias adjusted data were subjected to a number of tests to assure high quality. Besides manual checks on the performance of the bias adjustment performance and scanning of log-files from the production, QA was performed regarding variable dependent valid ranges, distributions of the variables, that data are valid in all land grid points following the reference data set. The climatological means of all models are well adjusted to the reference data, and very little bias remains in the distributions.
Figure 1 shows an example of the "before and after" annual distributions of each of the climate simulations. The spread has been dramatically reduced for both variables, and lie essentially on top of the EFAS-Meteo reference distribution, as is expected from the method. The slight deviations between the distributions are due mainly to the running 30-day window applied in the bias adjustments, compared to the 'calendar' window-based evaluation. For the precipitation, the low and moderate intensities dominate the distribution, and are well adjusted by the method. However, the wet bias in the extremes is still present in most models, although reduced. The uncertainties are large at the tail of the precipitation distribution, and this is a common issue in bias adjustment methods, and does not cause concern for the subsequent hydrological modeling.

Figure 1: Example of original (top) and bias adjusted (bottom) distributions for temperature (left) and precipitation (right) for a domain in central Europe. The different colours mark the EFAS-Meteo reference and the different members of the model ensemble.

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Ntegeka, V., P. Salamon, G. Gomes, H. Sint, V. Lorini, M. Zambrano-Bigiarini, and J. Thielen (2013) EFAS-Meteo: A European daily high-resolution gridded meteorological data set for 1990 – 2011, JRC Tech. Report, doi: 10.2788/51262.

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