Is there potential added value in COSMO\u2013CLM forced by ERA reanalysis data?

Abstract

An application of the potential added value (PAV) concept suggested by Di Luca et al. (Clim Dyn 40:443–464, 2013a) is applied to ERA Interim driven runs of the regional climate model COSMO–CLM. They are performed for the time period 1979–2013 for the EURO–CORDEX domain at horizontal grid resolutions 0.11^{circ }, 0.22^{circ }, and 0.44^{circ } such that the higher resolved model grid fits into the next coarser grid. The concept of the potential added value is applied to annual, seasonal, and monthly means of the 2 m air temperature. Results show the highest potential added value at the run with the finest grid and generally increasing PAV with increasing resolution. The potential added value strongly depends on the season as well as the region of consideration. The gain of PAV is higher enhancing the resolution from 0.44^{circ } to 0.22^{circ } than from 0.22^{circ } to 0.11^{circ }. At grid aggregations to 0.88^{circ } and 1.76^{circ } the differences in PAV between the COSMO–CLM runs on the mentioned grid resolutions are maximal. They nearly vanish at aggregations to even coarser grids. In all cases the PAV is dominated by at least 80% by its stationary part.