Understanding Sensitivity of Hurricane Intensity to Ice Nuclei Concentration Formulations

Microphysical processes play an important role in intensity and structural changes of hurricanes. Advancement in hurricane intensity forecasts requires improved physical parameterizations in numerical weather prediction models to account for complex processes involving ice microphysics. In this study, high resolution simulations using Navy's Coupled Ocean/Atmosphere Mesoscale Prediction System are employed to evaluate the impact of different formulations of ice nuclei concentration on hurricane intensity forecasts. An order of magnitude of difference in ice concentration at upper levels in the hurricane eyewall and anvil clouds results from established parameterizations of ice nuclei concentration. The storm intensity, thermodynamic structure, and turbulence distributions are substantially altered by varying the ice nuclei concentration formulations. The simulated hurricane intensity could differ by 32 hPa in mean sea level pressure and 40 m s-1 in surface maximum winds. A discussion of model results will include a comparison of simulated ice fields with ice observations obtained in hurricanes. Given the extreme sensitivity of hurricane intensity to ice processes, this study accentuates the need for better understanding ice microphysical processes and observational measurements of ice nuclei concentration in hurricanes.