The Impact of aerosol–ice nuclei-cloud interactions on a Typical Spring Dust-Precipitation Event in China

Abstract. To investigate the impact of ice nuclei (IN) activated by dust aerosols on precipitation over China, this study uses regional Global/Regional Assimilation and Prediction System – China Meteorological Administration Unified Atmospheric Chemistry Environment (GRAPES/CUACE). The original temperature-dependent IN nucleation scheme is improved by incorporating an on-line aerosol–IN nucleation scheme. The INs are fed on-line into the Double-Moment 6-Class (WDM6) cloud microphysics scheme in a typical dust affected precipitation event in East Asia.

The on-line aerosol–IN nucleation scheme modifies the spatial distribution and density of IN. Compared with the systematic underestimation in original WDM6, INs reach 10³–10⁴ L⁻¹ with the improved scheme, and cloud ice is reasonably formed between 2 and 6 km in height.

The scheme alters the distribution of cloud hydrometeors, making it closer to observations. Above the freezing level, the ice-phase hydrometeors mixing ratio decreases due to the higher cloud-top temperatures in dusty weather. And the ratio of cloud ice to cloud snow changes from 1:1 to 1:3. Near the freezing level, increased cloud ice converts to cloud water, resulting in its increasing. During the dust-precipitation event, rainwater is decreased due to vapor competition between IN and cloud condensation nuclei.

The scheme also modulates the precipitation distribution closer to observations. It suppresses precipitation near dust source areas, where accumulated precipitation decreased by about 1.5 mm, while the downstream precipitation increased by about 0.18 mm.