Internal Variability of the Climate System Mirrored in Decadal-Scale Trends of Surface Solar Radiation

We again used the unforced multi-century Coupled models intercomparison project – Phase 6 simulations (piControl) to investigate the possible causes of unforced trends in downwelling surface solar radiation. This time we branched of from known climate modes of variability like El Niño-Southern Oscillation, Pacific Decadal Oscillation, Atlantic Multidecadal Oscillation, etc. and linked trends in the climate indices to trends in surface solar radiation. The study revealed distinct regional patterns of large-scale variability of radiation that is related to the climate variability described by the specific climate index.

The figure below shows and example for surface solar radiation trend patterns related to the Pacific Decadal Oscillation.

One can use the known historical evolution of the climate indices to hypothesize on the influence of variability versus the other popular candidate: anthropogenic aerosols, over decadal trends in surface shortwave radiation in different regions.