Using Decadal Variability of Surface and Satellite-based Measurements of Surface Solar Fluxes to Assess Current and Long-term Projected Changes from CMIP-6

NASA projects that provide estimates of solar irradiance in the context of meteorological conditions (i.e., clouds, aerosols and gaseous constituents, etc.) spanning from 1983 to near present (i.e., Surface Radiation Budget (GEWEX SRB), Clouds and Earth’s Radiance Energy System – CERES and Modern Era Reanalysis-assimilation for Research and Applications – MERRA2, etc.).  Those data products provide nearly 40 years of covariant information from global to regional scales.  These records provide the opportunity to assess the decadal variability of these fluxes with the capability to attribute changes to various cloud and/or aerosol processes.  Utilizing these observations, we assess the long-term projections of the surface solar fluxes from CMIP6 model runs utilizing NASA’s Earth Exchange Global Daily Downscaled Projections (NEX-GDDP) data set (Thrasher et al., 2023) for three socio-economic pathways utilized by Climate Modeling Intercomparison Project (CMIP6) that span from 1950 to 2100 and includes projections of temperature and solar irradiance with 7 other parameters.  Over the Continental United States, we find that the data products used to downscale this NEX-GDDP needs to be re-evaluated but that the long-term changes in surface solar fluxes show very little trend.  However, the 2-4 decade variability is larger by as much as a factor of 4.  This has implications in terms of surface energy flux exchange at the surface and even for assessing the solar availability for solar power resources