Bob presented a seminar on “Basic Hurricane Microphysics (or, why I don’t like model output ice concentrations and distributions)”.
We have flown hurricanes for decades, and above the melting level from 1978 – 1992. What have we learned, and how can we use that knowledge to improve the numerical models?
If Hurricanes have an eyewall, they all have an extensive area of stratiform precipitation outside the eye, but storms that do not have a strong eyewall can be convective indeed. Model hurricanes produce a strong eyewall, but they do not create the external stratiform area that is always present in a natural storm. Furthermore, they do not simulate the eyewall replacement cycle that occurs naturally in low shear environments. One potential problem (not necessarily related to the microphysics) is the occurrence of scattered “popcorn” convection outside the eyewall. These cells propagate outward singly and do not form rain bands. All microphysics schemes exhibit this convection, and the Thompson scheme produces the best looking results.
A video recording of the presentation is available on the anonymous ftp site: