Understanding the impact of ice nucleation on lightning and rainfall: A case study

A suitable parameterization of heterogeneous ice nucleation (HIN) is essential for the effective simulation of ice processes in climate models and comprehending their interactions with aerosols. In this study, the influence of HIN formulations in Morrison two-moment bulk cloud microphysical scheme of the Weather Research and Forecasting (WRF-ARW) model in simulating the thunderstorm event over Maharashtra, India, has been evaluated. The HIN parameterization is used to simulate the thunderstorm event is based on Fletcher (1962), Cooper (1986), and Mayers et al. (1992), along with the inclusion of measurements of ice nucleation from SPectrometer for Ice Nuclei at High Altitude Cloud Physics Laboratory, Indian Institute of Tropical Meteorology (IITM-SPIN). The results signify that different ice nucleation formulations are highly sensitive in simulating rainfall and lightning by the formation of cloud hydrometeors (e.g., cloud ice, snow, graupel, and rain). The HIN of IITM-SPIN and Fletcher (1962) simulate the better lightning flashes and rainfall compared to Cooper (1986) and Mayers et al. (1992). The results from a two-dimensional idealized simulation also corroborate the role of the HIN on cloud microphysical processes. Clouds and precipitation processes are influenced by the ice nucleation process, which modifies latent heat release and eventually modulates the dynamics. Therefore, the present work can provide a pathway in the selection of a better ice nucleation formulation for better portrayal of cloud dynamics.