Radiative and microphysical effects of solid species on the intensity forecast of typhoon <i>Hato</i> (2017)

Abstract Radiative and microphysical forcing on the rapid intensification of tropical cyclone Hato (2017) is examined based on a newly developed global unstructured mesh atmospheric model. The different spatial distribution of solid hydrometeors simulated by two commonly used microphysical schemes (WSM6 and Thompson) induces spatial variance of radiative and microphysical heating within the circulation of the vortex. The production and existence of cloud ice in the outer cloudy area outside an eyewall‐like semicircle convective rainband mitigate the upward long‐wave radiation at the middle troposphere, destabilizing the air parcels with the aid of latent heating released from depositional growth and contributing to the enhancement of the direct transverse circulation. Due to such positive feedback, the simulated Hato from WSM6 undergoes a rapid intensification accompanied by an axisymmetrization process. However, abundant snow at the middle‐to‐high layer throughout the circulation of the vortex at the expense of cloud ice results in a stable stratification in the outer region of the primary rainband, inhibiting the continuous inward transportation of energy to the main‐core area in THOM (a partial double‐moment bulk microphysical scheme). Combined with the effect of mass loading, Hato simulated in THOM obtains limited intensity. Treating snow as cloud ice in THOM ensures that the spatial distribution of heating owing to long‐wave radiation and microphysics collaboratively determines the evolution of Hato . Moreover, the sensitivity experiment, which involves adjusting the threshold of cloud ice/snow and the relevant transferring processes in THOM, demonstrates the sensitivity to parameterization of solid hydrometeors. Consistent linkage between the microphysical and radiation schemes remains a challenge but urgently needs to be solved to improve tropical cyclone intensity forecasts.