Aerosol midlatitude cyclone indirect effects in observations and high-resolution simulations

Aerosol-cloud interactions are a major source of uncertainty in predicting 21st century climate change. Using high resolution, convection-permitting global simulations we predict that increased cloud condensation nuclei (CCN) interacting with midlatitude cyclones will increase their cloud droplet number concentration (CDNC), liquid water (CLWP), and albedo. For the first time this effect is shown with 13 years of satellite observations. Causality between enhanced CCN and enhanced cyclone liquid content is supported by the 2014 eruption of Holuhraun. The change in midlatitude cyclone albedo due to enhanced CCN in a surrogate climate model is around 70% of the change in a high-resolution convection-permitting model, indicating that climate models may underestimate this indirect effect.