Initial Transient Response of an Intensifying Baroclinic Wave to Increases in Cloud Droplet Number Concentration

Abstract

nsemble simulations of an idealized baroclinic wave were conducted with the WRF Model to investigate the effects of increased cloud droplet number concentration (DNC) on the development of the wave. Statistically significant differences between experiments where the DNC was doubled and the control experiments were identified for an initial transient period before the cyclone enters the stage of rapid intensification. Doubling of the DNC increases total cloud water in the model, lowers the cloud level, and enhances latent heating to the east of the surface low, which strengthens the midtropospheric ridge. Subsequent changes in dry dynamical processes [e.g., advection of potential vorticity (PV)] as a result of the ridge strengthening lead to the deepening of the trough and ultimately produce a mild yet statistically significant strengthening of the baroclinic wave as a result of the DNC doubling. Piecewise PV inversion further confirms the critical role that latent heating change plays in strengthening the midtropospheric ridge. Also discussed are the distinctions between aerosol?tropical cyclone interaction and aerosol?extratropical cyclone interaction.