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Black carbon (BC) exerts potential effects on climate, especially in the Tibetan Plateau (TP), where the cryosphere and environment are very sensitive to climate change. The TP saw a record-breaking aerosol pollution event during the period from 20 April to 10 May 2016. This paper investigates the meteorological causes of the severe aerosol pollution event, the transboundary transport flux of BC, the aerosol–meteorology feedback, and its effect on the transboundary transport flux of BC during the severe aerosol pollution event using observational and reanalysis datasets as well as simulation based on a coupled meteorology and aerosol/chemistry model, Weather Research and Forecasting model coupled with Chemistry (WRF-Chem). By analyzing weather maps derived from the reanalysis dataset, it is found that the plateau vortex and southerly winds were key factors that contributed to the severe aerosol pollution event. Subsequently, due to the good performance of the WRF-Chem model for the spatiotemporal characteristics of meteorological conditions and aerosols, the transboundary transport flux of BC during the pollution event was investigated. The results show that the vertically integrated cross-Himalayan transport flux of BC decreases from west to east, with the largest transport flux of 20.8 mg m -2 s -1 occurring at the deepest mountain valley in southwestern TP. Results from simulations with and without aerosol–meteorology feedback show that aerosols induce significant changes in meteorological conditions in the southern TP and the Indo-Gangetic Plain (IGP), with the atmospheric stratification being more stable and the planetary boundary layer height decreasing in both regions, and the 10 m wind speed increasing in the southern TP but decreasing in the IGP. Changes in meteorological conditions in turn lead to a decrease in the surface BC concentration in the southern TP of up to 0.16 µ g m -3 (50 %) and an increase in the surface BC concentration in the IGP of up to 2.2 µ g m -3 (75 %). In addition, it is found that the aerosol–meteorology feedback decreases the vertically integrated transboundary transport flux of BC from the central and western Himalayas towards the TP. This study not only provides crucial policy implications for mitigating glacier melt caused by aerosols over the TP but is also of great significance for the protection of the ecological environment of the TP. [ABSTRACT FROM AUTHOR]

Black carbon (BC) exerts potential effect on climate, especially in the Tibetan Plateau (TP), where the cryosphere and environment are very sensitive to climate change. The TP saw the record-breaking aerosol pollution event during the period from April 20 to May 10, 2016. This paper investigated the meteorological causes, trans-boundary transport flux of BC, and aerosol-meteorology feedback as well as its effect on trans-boundary transport flux of BC during this severe aerosol pollution event via using observational and reanalysis dataset and simulation from the coupled meteorology and aerosol/chemistry model (WRF-Chem). By analyzing the weather maps derived from reanalysis dataset, it is found that the plateau vortex and southerly winds were key factors that contributed to the severe aerosol pollution event. Subsequently, with the good performance of WRF-Chem model on the spatiotemporal characteristics of meteorological conditions and aerosols, the trans-boundary transport flux of BC during the pollution event was investigated. The results show that the vertically integrated cross-Himalayan transport flux of BC decreases from west to east, with the largest transport flux of 20.8 mg m−2 s−1 occurring at the deepest mountain valley in southwestern TP. Results from simulations with and without aerosol-meteorology feedback show that aerosols induce significant changes in meteorological conditions in the southern TP and Indo-Gangetic Plain (IGP), with the atmospheric stratification being more stable and the planetary boundary layer height decreasing in both regions, and 10-m wind speed increasing in the southern TP but decreasing in the IGP. Changes in meteorological conditions in turn lead to a decrease of surface BC concentration with value up to 0.16 μg/m3 (50 %) in the southern TP and an increase of surface BC concentration with value up to 2.2 μg/m3 (75 %) in the IGP. By excavating the impact of aerosol-meteorology feedback on the trans-boundary transport flux of BC, it has been acquired that the aerosol-meteorology feedback decreases the integrated transport flux of BC from central and western Himalayas towards the TP. This study not only provides crucial policy implications for mitigating glacier melt caused by aerosols over the TP, but also is of great significance to the ecological environment protection for the TP. [ABSTRACT FROM AUTHOR]

Black carbon (BC) exerts potential effect on climate, especially in the Tibetan Plateau (TP), where the cryosphere and environment are very sensitive to climate change. The TP saw the record-breaking aerosol pollution event during the period from April 20 to May 10, 2016. This paper investigated the meteorological causes, trans-boundary transport flux of BC, and aerosol-meteorology feedback as well as its effect on trans boundary transport flux of BC during this severe aerosol pollution event via using observational and reanalysis dataset and simulation from the coupled meteorology and aerosol/chemistry model (WRF-Chem). By analyzing the weather maps derived from reanalysis dataset, it is found that the plateau vortex and southerly winds were key factors that contributed to the severe aerosol pollution e vent. Subsequently, with the good performance of WRF-Chem model on the spatiotemporal characteristics of meteorological conditions and aerosols, the trans-boundary transport flux of BC during the pollution event was investigated. The results show that the vertically integrated cross-Himalayan transport flux of BC decreases from west to east, with the largest transport flux of 20.8 mg m-2 s-1 occurring at the deepest mountain valley in southwestern TP. Results from simulations with and without aerosol-meteorology feedback show that aerosols induce significant changes in meteorological conditions in the southern TP and Indo-Gangetic Plain (IGP), with the atmospheric stratification being more stable and the planetary boundary layer height decreasing in both regions, and 10-m wind speed increasing in the southern TP but decreasing in the IGP. Changes in meteorological conditions in turn lead to a decrease of surface BC concentration with value up to 0.16 μg/m³ (50%) in the southern TP and an increase of surface BC concentration with value up to 2.2 μg/m³ (75%) in the IGP. By excavating the impact of aerosol-meteorology feedback on the trans-boundary transport flux of BC, it has been acquired that the aerosol-meteorology feedback decreases the integrated transport flux of BC from central and western Himalayas towards the TP. This study not only provides crucial policy implications for mitigating glacier melt caused by aerosols over the TP, but also is of great significance to the ecological environment protection for the TP. [ABSTRACT FROM AUTHOR]

The Pan-Third Pole (PTP) owns complex geography and demographic features where aerosol roles and their impact cannot be neglected as it jeopardizes both the environment and human health. Therefore, we analyzed spatio-temporal aerosol concentration, the influence of meteorological conditions, and underlying aerosol transport mechanisms over the PTP by leveraging observation, satellite dataset, and model outputs. The observation and model simulation result showed that aerosol concentrations exceeded the world health organization (WHO) and China guideline values in most of the locations. This study revealed distinctive seasonality with the highest and lowest aerosol concentrations during the winter and summer seasons, respectively, which could be favored by meteorological conditions and emissions from biomass burning. In response to higher aerosol concentrations, the maximum aerosol optical depth (AOD) values were observed over the major hotspot regions however, interestingly summer high (AOD > 0.8) was observed over the Indo Gangetic Plain (IGP) in South Asia. The columnar aerosol profile indicated that the higher aerosol concentrations were limited within 1-2 km elevation over the densely populated regions over South Asia and Eastern China. However, the significant aerosols concentrations found to be extended as high as 10 km could potentially be driven by the deep convection process and summer monsoon activities. Regionally, the integrated aerosol transport (IAT) for black carbon (BC) and organic carbon (OC) was found to be maximum over SA. Noticeable OC IAT anomaly (~5 times > annual mean) found during spring that was linked with the biomass burning events. Yet, the dust transportation was found to be originated from the arid land and deserts that prolonged especially during summer followed by spring seasons. This study highlights the driver mechanism in aerosol seasonality, transport mechanism, and further motivates the additional assessment into potential dynamic relation between aerosol species, aerosol atmospheric river, and its societal impact. [ABSTRACT FROM AUTHOR]