WRF-Chem Simulation of an East Asian Dust-Infused Baroclinic Storm (DIBS)

Observations of dust-infused baroclinic storm (DIBS) clouds (Fromm et al., 2016, ) have revealed Saharan and Asian storm systems with mineral dust mixed with overrunning cirrus shield clouds at altitudes of 8-10km. The unique characteristics observed in these clouds, including intense Cloud-Aerosol LIdar with Orthogonal Polarization lidar backscatter and large daytime 3.9- to 11-m brightness temperature differences (indicating relatively small ice crystals), have prompted this modeling study to determine the mineral dust pathway and dynamics, if any, through an observed DIBS. We use the Advanced Weather Research and Forecasting Model with the chemistry model (WRF-Chem) and constrained with the WRF data assimilation system (WRF-DA) to conduct a reanalysis of an East Asian DIBS from 6 to 11 April 2010. Desert dust emission via the Global Ozone Chemistry Aerosol Radiation and Transport dust emission scheme (Ginoux et al., 2001, ) and transport from both the Taklimakan and Gobi deserts is simulated within WRF-Chem with the Model for Simulating Aerosol Interactions and Chemistry aerosol treatment (Zaveri et al., 2008, ). In-line air mass trajectories were used to source and trace dust transport from the storm spin-up through dissipation 4days later. Results show rapid dust transport from the Gobi desert to cirrus cloud tops via the warm conveyor belt mechanism, with the dust mixed throughout the cloud at altitudes from 5 to 10km. Results are verified by good qualitative agreement with Cloud-Aerosol LIdar with Orthogonal Polarization observations at several different moments in the DIBS cycle, including an elevated layer of dust that remains after storm cloud dissipation. These results confirm the potential for routine and significant dust-cloud processing in DIBS cases, affecting both cloud properties and identifying a previously unidentified pathway for long-range transport of dust.