Analytical treatment of ice sublimation and test of sublimation parameterisations in two�moment ice microphysics models

Abstract

We derive an analytic solution to the spectral growth/sublimation equation for ice crystals and apply it to idealised cases. The results are used to test parameterisations of the ice sublimation process in two�moment bulk microphysics models. Although it turns out that the relation between number loss fraction and mass loss fraction is not a function since it is not unique, it seems that a functional parameterisation is the best that one can do in a bulk model. Testing a more realistic case with humidity oscillations shows that artificial crystal loss can occur in simulations of mature cirrus clouds with relative humidity fluctuating about ice saturation.