On the response of hailstorms to enhanced CCN concentrations

In this study we explore the role that cloud base height (or cloud base temperature) plays in the response of hailstorms to increased concentrations of cloud condensation nuclei (CCN). A rather large number of cloud-resolving simulations were performed which explored the parameter space varying both potential CCN concentration and cloud base heights, using a microphysical scheme that predicts 3-moments of the hail size distribution. Several simulated quantities exhibited distinct responses to enhanced CCN concentrations depending on the cloud base altitudes. For instance, positive changes prevailed in the number concentration and the predominant diameter of hailstones on the surface, the integral mass of hail precipitation and the peak rates for high cloud base heights or a deeper layer between cloud base and the freezing level. Conversely, weak effects prevailed for numerical experiments initialized with lower cloud bases.