Dagan, ..., Romps, ..., RCEMIP-ACI: Aerosol-cloud interactions in a multimodel ensemble of radiative-convective equilibrium simulations, JAMES, 2025
Paper
Description
Air pollution is hypothesized to affect clouds and the atmosphere in a variety of ways. These effects are very difficult to measure from observations because we have only one atmosphere, which has been polluted, and so there is no observable clean atmosphere to use in a comparison. Models can help, of course, because they can run simulations with and without the air pollution, but any one model is hard to trust.
Therefore, this study looks for the hypothesized effects in 11 different models, of which DAM is one. If the models agree on an effect, then that makes it much more likely that the effect is operating in the real atmosphere. This study finds that some effects of air pollution are robust, like the suppression of warm rain and an increase in humidity. But a consistent effect of air pollution on convective intensity (cloud updraft speeds), as predicted by the warm-phase invigoration hypothesis, is not found. Instead, the effect of air pollution on updraft speeds is found to be small in magnitude (less than 1 m/s in 10 of 11 models) and of inconsistent sign.
Average change in convective intensity (defined as the 99.999 percentile of updraft speeds) between simulations with aerosol number concentrations of 20, 200, and 2000 cm-3 for small RCE simulations with sea surface temperatures of 295, 300, and 305 K.