Radiative absorption enhancement of dust mixed with anthropogenic pollution over East Asia

Abstract

Abstract. The particle mixing state plays a significant yet poorly quantified role in aerosol radiative forcing, especially for the mixing of dust (mineral absorbing) and anthropogenic pollution (black carbon absorbing) over East Asia. We have investigated the absorption enhancement of mixed-type aerosols over East Asia by using the Aerosol Robotic Network observations and radiative transfer model calculations. The mixed-type aerosols exhibit significantly enhanced absorbing ability than the corresponding unmixed dust and anthropogenic aerosols, as revealed in the spectral behavior of absorbing aerosol optical depth, single scattering albedo, and imaginary refractive index. The aerosol radiative efficiencies for the dust, mixed-type, and anthropogenic aerosols are −101.0, −112.9, and −98.3 Wm −2 τ −1 at the bottom of the atmosphere (BOA); −42.3, −22.5, and −39.8 Wm −2 τ −1 at the top of the atmosphere (TOA); and 58.7, 90.3, and 58.5 Wm −2 τ −1 in the atmosphere (ATM), respectively. The BOA cooling and ATM heating efficiencies of the mixed-type aerosols are significantly higher than those of the unmixed aerosol types over the East Asia region, resulting in atmospheric stabilization. In addition, the mixed-type aerosols correspond to a lower TOA cooling efficiency, indicating that the cooling effect by the corresponding individual aerosol components is partially counteracted. We conclude that the interaction between dust and anthropogenic pollution not only represents a viable aerosol formation pathway but also results in unfavorable dispersion conditions, both exacerbating the regional air pollution in East Asia. Our results highlight the necessity to accurately account for the mixing state of aerosols in atmospheric models over East Asia in order to better understand the formation mechanism for regional air pollution and to assess its impacts on human health, weather, and climate.

Relationship between Asian monsoon strength and transport of surface aerosols to the Asian Tropopause Aerosol Layer (ATAL): interannual variability and decadal changes

“…This is because the MERRA-2 emission inventories of aerosols species have not been updated since the mid-2000s (Randles et al, 2017). Moreover, recent modeling studies have suggested that the mixing state and aging processes can largely change the aerosol lifetime during simulation, and consequently affect the amount of aerosols lifted to UTLS, and some optical measurements further support the result that dust aerosol can be coated by anthropogenic aerosols over east Asia and then significantly enhance absorbing ability Tian et al, 2018). Nonetheless, our findings provide a working hypothesis that warrants further investigations using both modeling and observational studies.…”

“…This could be related to a warming trend of the land surface over northern India and the desert regions to the west (Jin and Wang, 2017). A warmer and drier land surface before monsoon onset is likely to favor increased biomass burning emissions (van der Werf et al, 2006) (Fig. S5).…”

Hygroscopicity of Different Types of Aerosol Particles: Case Studies Using Multi-Instrument Data in Megacity Beijing, China

“…In Case I, the irregular dust particles with high vertical depolarization ratio mainly concentrated near the ground (below 480 m) and contributed more to the overall β in this area. This suggests that dust was generated locally [59,60]. Within the same range of RH, the backscattering coefficient of the non-dust particles increased faster than the total backscattering coefficient.…”

“…Remote Sens. 2020, 11, x; doi: FOR PEER REVIEW www.mdpi.com/journal/remotesensing [59,60]. Within the same range of RH, the backscattering coefficient of the non-dust particles increased faster than the total backscattering coefficient.…”

Vertical Structures of Dust Aerosols over East Asia Based on CALIPSO Retrievals

“…In contrast, less developed areas with smaller populations across the Tibetan Plateau and eastern Inner Mongolia constituted the low AOD centers. In addition to natural dust aerosols, aerosols emitted by anthropogenic activities, such as smoke particles from burning of agricultural biomass, sulphate and black and organic carbon aerosols from industrial activities could be responsible for enhanced levels of aerosol loadings during DJF over the SC with a high AOD value of 0.88 [38][39][40].…”