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An RCM multi-physics ensemble over Europe: Multi-variable evaluation to avoid error compensation

Revista: Climate Dynamics
Año: 2015  
Estado: Publicado
En este estado desde: 25 Feb 2015
Archivo PDF: Garcia-Diez_2015.CLIDY.Error_Compensation_accepted.pdf
DOI: 10.1007/s00382-015-2529-x
, , Vautard,R.

Regional Climate Models (RCMs) are widely used tools to add detail to the coarse resolution of global simulations. However, they are known to be affected by biases. The overall complexity of the system, with the presence of many feedbacks, makes difficult to trace model errors. Thus, in many previous studies, these biases are described but their underlying causes and mechanisms are often left unknown. In this work we show how a multi-physics ensemble can be used to thoroughly analyse the main biases affecting an RCM over Europe (Euro-CORDEX domain). This is achieved by comparing the model results with temperature and precipitation observational products, as well as with cloud cover, radiative fluxes and soil moisture. It is found that, during winter, the model suffers a significant cold bias over snow covered regions. This is shown to be related with a poor representation of the snow cover. During summer, a large sensitivity to the cumulus parameterization is found, related to large differences in the cloud cover and short wave radiation flux. Also, a daily reforecast is used to study the model error dependence on the spin-up. Results show also that small errors in one variable are often a product of compensation of errors, so the high dimensionality of the model evaluation problem cannot be disregarded.

NOTE: The attached version is the accepted manuscript. The final publication is available at Springer via http://dx.doi.org/10.1007/s00382-015-2529-x.