North Atlantic Storm-Track Sensitivity to Warming Increases with Model Resolution

Mesoscale condensational heating can increase the sensitivity of modeled extratropical cyclogenesis to horizontal resolution. Here a pseudo global warming experiment is presented to investigate how this heating-enhanced sensitivity to resolution changes in a warmer and thus moister atmosphere. The Weather Research and Forecasting (WRF) Model with 120- and 20-km grid spacing is used to simulate current and future climates. It is found that the North Atlantic storm-track response to global warming is amplified at the higher model resolution. The most dramatic changes occur over the northeastern Atlantic, where resolution typical of current general circulation models (GCMs) results in a smaller global warming response in comparison with that in the 20-km simulations. These results suggest that caution is warranted when interpreting projections from coarse-resolution GCMs of future cyclone activity over the northeastern Atlantic.