Forecast skill of multi‐year seasonal means in the decadal prediction system of the Max Planck Institute for Meteorology

We examine the latest decadal predictions performed with the coupled model MPI‐ESM as part of the Coupled Model Intercomparison Project Phase 5 (CMIP5). We use ensembles of uninitialized and yearly initialized experiments to estimate the forecast skill for surface air temperature. Like for its precursor, the initialization of MPI‐ESM improves forecast skill for yearly and multi‐yearly means, predominately over the North Atlantic for all lead times. Over the tropical Pacific, negative skill scores reflect a systematic error in the initialization. We also examine the forecast skill of multi‐year seasonal means. Skill scores of winter means are predominantly positive over northern Europe. In contrast, summer to autumn means reveal positive skill scores over central and south‐eastern Europe. The skill scores of summer means are attributable to an observed pressure‐gradient response to the North Atlantic surface temperatures.