To date, the radiative impact of dust and the Saharan air layer (SAL) on North Atlantic hurricane activity is not yet known. According to previous studies, dust stabilizes the atmosphere due to absorption of solar radiation but thus shifts convection to regions more conducive for hurricane genesis. Here we analyze differences in hurricane genesis and frequency from ensemble sensitivity simulations with radiatively active and inactive dust in the aerosol‐climate model ECHAM6‐HAM. We investigate dust burden and other hurricane‐related variables and determine their influence on disturbances which develop into hurricanes (developing disturbances, DDs) and those which do not (nondeveloping disturbances, NDDs). Dust and the SAL are found to potentially have both inhibiting and supporting influences on background conditions for hurricane genesis. A slight southward shift of DDs is determined when dust is active as well as a significant warming of the SAL, which leads to a strengthening of the vertical circulation associated with the SAL. The dust burden of DDs is smaller in active dust simulations compared to DDs in simulations with inactive dust, while NDDs contain more dust in active dust simulations. However, no significant influence of radiatively active dust on other variables in DDs and NDDs is found. Furthermore, no substantial change in the DD and NDD frequency due to the radiative effects of dust can be detected.

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.

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.

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