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Dust aerosols have significant impact on the environment and climate through long-range transport. We report, in this paper, a case of dust–cloud interaction process using combined measurements of a ground-based polarization and Raman (PR) lidar systems, and implemented by the spaceborne Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) lidar observations. The dust event occurred on 14 March 2009 over East Asia. During the two hours of observing time, the ground-based lidar observed an ongoing process of decreasing of the depolarization ratio (DR) accompanied by the increase of the water vapor simultaneously, indicating a dust–cloud interaction and particle transformation. CALIPSO measurements also found similar layers of dusts and clouds over lands and oceans with properties similar to the ground based lidar measurements. Our observation was a real-time dust–cloud process with the observation of occurrence of particle transformation. The depolarization reduced from 0.2 to 0.1 corresponding to a change of aspect ratio from 1.2 to 1.1. A discussion of a dust–cloud interaction in terms of three-stage cloud processes is made based on back-trajectory analyses and lidar observations. The result shows that dust aerosols decrease the cloud extinction coefficient by 41% but increase the cloud optical depth (COD) of water cloud by 12.79%, compared with that of pure water clouds. Furthermore, if dust aerosols participate as cloud condensation nuclei (CCN) in cloud physical processes, then they significantly reduce the size of the cloud droplet by 44–79%. Finally, based on three-year collocated CALIPSO and CloudSat measurements from 2007 to 2010, we found approximately one-third of clouds are originally dusty in the spring over the Pacific Coast areas. [ABSTRACT FROM AUTHOR]

Mineral dust from the deserts and arid areas in East Asia plays a critical role in regional climate and air quality. Based on integrated satellite observations and MERRA-2 reanalysis, we provide an observational insight into dust activities governing spatial patterns of dust aerosols over East Asia. With Moderate resolution Imaging Spectroradiometer Aerosol Optical Depth (AOD) and Ozone Monitoring Ultraviolet Aerosol Index (UVAI), fixed dust-active areas with distinct spatial-temporal differences are revealed. Besides the few dust storms mostly in spring, unnoticeable but frequent dust plumes are found to be the predominant sources of prevailing dust particles over East Asia. Compared with the active dust sources in Taklimakan Desert throughout the year, dust activities in Gobi deserts are at a much lower frequency. The elevated dust plumes are concentrated within 2–6 km over the deserts with large seasonal variations, and can be transported downstream to eastern China and Sichuan Basin within 3–5 days. Moreover, owing to the lack of enough strong winds, these dust plumes tend to be concentrated above the haze layers near surface in eastern China. The intense temperature inversion during winter and early spring can delay the mixing of dust-pollution. Despite a generally reasonable performance in dust AOD, MERRA-2 reanalysis exhibits some uncertainties in reproducing spatial locations of dust hotspots, dust concentration, and transport process. Our results emphasize significant role of the inapparent but prevalent dust plumes in air quality and in climate effects of East Asia. • Inapparent but frequent dust plumes are the predominant sources of prevalent dust aerosols over East Asia. • Dust plumes tend to overlay over anthropogenic pollution near surface with a delaying dust-pollution mixing. • MERRA-2 underestimates the dust loading in Taklimakan Desert and overestimates in Gobi deserts. [ABSTRACT FROM AUTHOR]

Wind-blown dust plays a crucial role in air quality, biogeochemical cycles, and climate change. In East Asia, one of the main dust source regions in the world, dust storms frequently engulf eastern China, with a substantial negative effect on air pollution and the ecological environment. By integrating multiple observations and the online coupled meteorology-chemistry model WRF-Chem, a severe dust storm event originating from the Gobi Desert in early May 2017 is comprehensively analyzed from the perspective of emission estimation, meteorological feedback, and the possible impact on the ecological environment. We optimize the size distribution of dust aerosol by applying local observations to better represent dust emission and regional transport in the model. Both the observations and simulations indicate that the dust storm broke out with PM 10 concentrations exceeding 1500 μg/m3 in the source region of the Gobi Desert, and was quickly transported downwind, deteriorating the air quality of cities in northern and eastern China. Moreover, we find that the dust storm significantly perturbed the temperature stratification, since mineral dust is a radiatively active aerosol and can absorb both short- and long-wave radiation. The upper dust layer at an altitude of around 2–3 km became warmer by 1–2 °C while the surface temperature decreased by about 2 °C, making the planetary boundary layer more stable and indirectly aggravating local air pollution near the ground in eastern China. Furthermore, during this event, a large amount of dust deposition increased ocean primary productivity, with the maximum Chlorophyll-a concentration rising from 4 to 14 mg/m3 in the central area of the Yellow Sea. This study highlights the critical impact of Asian dust pollution on air quality and marine ecosystems in downwind areas. • Modified WRF-Chem dust particle size distribution significantly improved the simulation ability of dust. • Multiple observations combined with model results to analyse dust episode comprehensively. • Dust aerosol makes the upper layer warm and the lower layer cool, increasing the stability of the boundary layer. • Dust deposited into the ocean is significantly associated with phytoplankton blooms. [ABSTRACT FROM AUTHOR]