Aerosol-meteorology feedback diminishes the trans-boundary transport of black carbon into the Tibetan Plateau
Abstract. 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.
Yuling Hu et al.
Status: open (until 05 Jun 2023)
- RC1: 'Comment on egusphere-2023-252', Anonymous Referee #1, 14 May 2023 reply
- RC2: 'Comment on egusphere-2023-252', Anonymous Referee #2, 17 May 2023 reply
Yuling Hu et al.
Yuling Hu et al.
Viewed (geographical distribution)
The manscript reported a record-breaking aerosol pollution event in the TP. Cross-boundary transport along the south slope the Himalayas from the surrounding regions was clearly the cause, implying galcier melt and ecological environment disturbtion for the TP. Due to the extremely scarce avaiblity of field observations, however, cross-boundary transport flux, meterological pattern delivering aerosol, and the aerosol-meteorology feedback have rarely been discussed. The manuscript clearly shows strong aerosol-meteorology feedback on the transpor flux of aerosols. The strong feedback on meteorology and aerosol distribution are also discussed in details. I hence recommanded this manuscript for publication in ACP.