Quantitative Assessment of Black Carbon over Southern China During Springtime: Regional and Sectoral Sources and the Impacts of East Asian Summer Monsoon Onset
Abstract
Previous studies emphasized that abundant black carbon (BC) originating from strong biomass burning (BB) in peninsula Southeast Asia (PSEA) can transport to Southern China (SC) during springtime, while its long-term contributions to BC over SC remain unquantified. East Asian Summer Monsoon (EASM) is also established in spring when the zonal wind direction starts to reverse and affects the regional transport of BC over SC. However, the impacts of EASM onset time on BC distribution and sources are unclear. In this study, A BC-tagging-technique that can track the regional and sectoral sources of BC simultaneously is added into the Community Earth System Model. We quantify the BC sources at different altitudes over SC in spring from 2000 to 2014 driven by offline meteorological field MERRA. Results show that about 64% of BC column burden (BCC) and 27% of BC surface concentration (BCS) over SC can be attributed to non-local sources, and their largest remote regional sources are PSEA (20%) and Northern China (NC; 18%), respectively. Though local BB emission contributes little to BC over SC, the proportion of BB sector increases from the surface (3%) to the upper air (13%), which can be attributed to that BC from PSEA mainly transport in the middle and upper troposphere (above 850 hPa). BB emission from PSEA accounts for about 80% of BCC in the BB sector over SC. BC from NC is largely composed of residential (50~60%) and industrial (30~40%) sectors and its main transport layer is lower troposphere (below 850 hPa). An emission-fixed simulation shows that the interannual variation in BC concentrations over SC is positively related to the varying EASM onset times (r=0.66, p<0.05), which is mainly resulted from the BC outflow/inflow transported from NC. When EASM onset time is early (late), a southerly (northerly) wind anomaly occurs and blocks (promotes) the southward transport of BC from NC to SC, thus leading to a BC decrease (increase) in SC but a BC increase (decrease) in NC. The varying EASM onset times induce a -5~7% variation in BCC and a -2~7% variation in BCS over SC, which is comparable to the impacts of EASM strength on BC concentrations.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMA219.0011F
- Keywords:
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- 0305 Aerosols and particles;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 3311 Clouds and aerosols;
- ATMOSPHERIC PROCESSES;
- 3337 Global climate models;
- ATMOSPHERIC PROCESSES;
- 3359 Radiative processes;
- ATMOSPHERIC PROCESSES