Extremely High Concentrations of Ice Particles in East Asian Dust-Infused Baroclinic Storm (DIBS) Cirrus Shield: Dominant Role of Dust Ice Nucleation Effect

Acting as efficient ice-nucleating particles, dust particles can affect cirrus cloud properties through heterogeneous nucleation. A dust-infused baroclinic storm (DIBS) over East Asia in May 2017 was examined using satellite observations and the Weather Research and Forecasting model coupled with chemistry (WRF-Chem) to study the dust effects on cirrus clouds. Satellite observations showed that the ice number concentration (N-ice) was extremely high, exceeding 1-10 cm(-3) at the cirrus shield of the DIBS, and the ice effective radius (r(ei)) was about 10-30 mu m. An aerosol-aware heterogeneous ice nucleation parameterization (Ullrich et al., 2017, ) was implemented into WRF-Chem to explore the formation mechanism of such a high N-ice. The simulated N-ice from Ullrich17 was 1-2 orders of magnitude higher than that from the default scheme (Cooper, 1986, ), and the r(ei) was 2-3 times smaller. The results from Ullrich17 were more consistent with satellite observations, which can be attributed to the enhanced deposition nucleation from the high dust concentrations. Our results demonstrated that the extremely high N-ice could be fully explained by the heterogeneous nucleation of dust particles in DIBS. A conceptual framework is proposed to explain the dust-cloud interactions in DIBS. This study confirms the significant dust effects on cirrus clouds in DIBS and highlights the importance of using aerosol-aware ice nucleation parameterizations in modeling cirrus clouds when the dust is present.