In this study we compare solar radiation at the surface from observations and Earth system models from 1961 to 2014. We find that the models do not reproduce the so-called global dimming as found in observations. Only model experiments with anthropogenic aerosol emissions display any dimming at all. The discrepancies between observations and models are largest in China, which we suggest is in part due to erroneous aerosol precursor emission inventories in the emission dataset used for CMIP6.

Spatio-temporal disparity to assess global dimming and brightening phenomena has been a critical topic. For instance, few studies addressed Surface Solar Irradiance (SSR) long-term trend in South America. In this study, SSR, Sunshine Duration (SD) and the Diurnal Temperature Range (DTR), are analyzed for São Paulo, Brazil. We found a dimming phase, identified by SSR, SD and DTR, extending till 1983. Then, while SSR is still declining, consistent with cloud increasing, SD and DTR are increasing.

This paper proposes a novel and accurate method for estimating and reconstructing aerosol optical depth from sunshine duration measurements under cloud-free conditions at any place and time since the late 19th century. The method performs very well when compared to AErosol RObotic NETwork measurements and operates an efficient detection of signals from massive volcanic eruptions. Reconstructed long-term aerosol optical depths are in agreement with the dimming/brightening phenomenon.

We report a model sensitivity study on the impact of aerosol–radiation interaction (ARI) changes in Europe between 1990 and 2010 on summer surface ozone via effects on photolysis rates and biogenic emissions. The overall impact of ARI changes on ozone was relatively small when compared to the total ozone concentrations, but it was more important when compared to the order of magnitude of ozone trends, indicating a potential partial damping of the effects of ozone precursor emissions' reduction.

A large number of radiometers used to measure solar and terrestrial broadband radiation are traceable to World Standard Groups at PMOD/WRC in Davos, Switzerland. A small correction of each group may be required in the future, and this study examines the methods and implications of this on data sets collected at four remote baseline stations since the 1990s. The goal is to develop a better estimate of the solar and terrestrial radiation budget at the Earth's surface.