Impacts of El Niño and Aerosols on Cloud Radiative Effects
Inter-annual variability in cloud radiative effects is driven by mid-level and high clouds. Both natural aerosol emissions and concentrations enhance the variability.
This study reveals the importance of aerosols to the inter-annual variability of cloud radiative effects.
A research team, including scientists from the Department of Energy’s Pacific Northwest National Laboratory, used three 150-year pre-industrial simulations of the Community Earth System Model to quantify the impacts of El Niño events on shortwave and longwave cloud radiative effects. They found that the El Niño cycle dominates inter-annual variations of cloud radiative effects. Sensitivity tests showed that variations of cloud radiative effects are mainly driven by El Niño-related changes in the cloud fraction. Aerosols contribute to 10–30% of the inter-annual variability of cloud radiative effects over the tropics.