2015~2050年南亚与东南亚输送对中国大气臭氧浓度的影响

The impacts of transport from South and Southeast Asia on O_(3) concentrations in China from 2015 to 2050

使用戈达德对地观测系统化学传输模型(Goddard Earth Observing System Chemical Transport Model,GEOSChem)模拟了不同共享社会经济路径(shared socioeconomic pathways,SSPs)下2015~2050年中国、南亚和东南亚地区的日最大8小时臭氧(MDA8 O_(3))浓度以及人为和生物质燃烧排放变化导致的南亚和东南亚输送变化对中国O_(3)浓度的影响.南亚和东南亚输送对中国O_(3)的影响涵盖珠江三角洲(简称珠三角)、广西、云南、贵州、四川盆地、青海、西藏以及新疆部分区域,使上述区域2015年MDA8 O_(3)年均浓度上升3.0~19.0μg m^(−3).在典型污染区域,2015年南亚和东南亚传输对四川盆地MDA8 O_(3)浓度影响最大(+6.2μg m^(−3)),珠三角随后(+4.7μg m^(−3)),长江三角洲(简称长三角)影响最小(+0.6μg m^(−3)).传输对典型污染区域MDA8 O_(3)的影响有明显的月变化特征:伴随春季地表和850 hPa高度30°N附近较强的西风与西南风,对四川盆地2015年MDA8 O_(3)的影响在3月最大(+10.1μg m^(−3)),4月随后(+9.4μg m^(−3));由于夏季地表和850 hPa处在10°~30°N区域盛行西南风,传输对珠三角的影响在7月最大(+14.0μg m^(−3)),8月次之(+9.1μg m^(−3)),对长三角的贡献在7月最高(+2.5μg m^(−3)),6月次之(+1.4μg m^(−3)).从中长期看,2015~2030年南亚和东南亚传输对上述区域MDA8 O_(3)的影响在SSP1尤其是SSP1-1.9情景下降低(四川盆地4月下降最大为3.5μg m^(−3)(−36.5%,2030年相较2015年的传输变化量与2015年传输量的比值),珠三角和长三角在7月下降最大,分别下降3.0(−21.1%)和1.1μg m^(−3)(−43.1%));传输贡献在SSP3-7.0情景下增加(相较2015年,2030年贡献在四川盆地5月增加20.1%,在珠三角和长三角7月分别增加8.5%和7.5%).上述三个区域的MDA8 O_(3)浓度受南亚和东南亚传输影响的长期(2015~2050年)变化特征与中长期类似.

Although the significant decrease in PM_(2.5)concentrations across China in response to the Air Pollution Prevention and Control Action Plan during 2013–2017,the ozone(O_(3))concentrations have increased rapidly.Previous studies have revealed that long-range transboundary transport from South Asia(SA)and Southeast Asia(SEA)greatly influences the O_(3)concentrations in China;however,these studies majorly focused on biomass burning events.The impact of anthropogenic emissions from neighboring countries on China’s O_(3)pollution has not been comprehensively and quantitatively investigated.In addition,the analysis of the impact of future transport from SA and SEA on O_(3)concentrations in China is required.Based on(Shared Socioeconomic Pathways)SSPs,a new set of future emission inventories,this study estimated the MDA8 O_(3)concentrations in China,SA,and SEA under different SSPs scenarios from 2015 to 2050 with varying anthropogenic and open burning emissions using a three-dimensional chemical transport model(GEOS-Chem).Several sensitivity experiments were simulated to quantitatively assess the impact of anthropogenic and open burning emission changes in SA and SEA on the future atmospheric O_(3)concentrations in China.Transport from SA and SEA can influence MDA8 O_(3)concentrations in China widely,covering the Pearl River Delta(PRD),Guangxi,Yunnan,Guizhou,Sichuan Basin(SCB),Qinghai,Tibet and parts of Xinjiang.It contributed to an increase in annual mean MDA O_(3)concentrations over above regions by 3.0–19.0μg m^(−3)in 2015,and led to an increase in MDA8 O_(3)concentration in China by 4.0μg m^(−3).Monthly variation characteristics of the impacts of SA and SEA transport on concentrations of MDA O_(3)in SCB,PRD,and YRD regions were further explored in this study.In 2015,the regional transport from SA and SEA had the highest impact on the MDA8 O_(3)concentrations in SCB,increased its annual mean concentration by 6.2μg m^(−3),followed by PRD(+4.7μg m^(−3)),and YRD(+0.6μg m^(−3)).Accompanied by the strong westerly and southwesterly winds on the surface and 850 hPa near 30°N in spring,the influence of transport from SA and SEA on MDA8 O_(3)concentrations was highest in SCB in March 2015(+10.1μg m^(−3),+7.2%),followed by April(+9.4μg m^(−3),+6.4%).Due to the prevailing southwesterly winds at 10°–30°N on the surface and 850 hPa in summer,the contribution attained its peak in July(+14.0μg m^(−3),+10.4%),followed by August(+9.1μg m^(−3),+6.5%)in PRD,while it peaked in July(+2.5μg m^(−3),+1.7%),followed by June(+1.4μg m^(−3),+0.9%)in YRD.Based on medium and long-term perspectives(2015–2030),the impact of transport from SA and SEA on MDA8 O_(3)concentrations in SCB,PRD,and YRD from 2015 to 2030 were simulated.Substantive reductions under SSP1,especially under SSP1-1.9 pathway were observed(the largest decline in SCB was−3.5μg m^(−3)(−36.5%)in April,and−3.0μg m^(−3)(−21.1%)and−1.1μg m^(−3)(−43.1%)in PRD and YRD,respectively,in July).The MDA8 O_(3)concentrations in SCB,PRD,and YRD during 2015–2030 were projected to increase under SSP3-7.0 scenario(the highest increase in the SCB will be+1.5μg m^(−3)(+20.1%)in May,and+1.2μg m^(−3)(+8.5%)and 0.2μg m^(−3)(+7.5%)in July,respectively,in PRD and YRD).Therefore,controlling O_(3)pollution due to the transport from SA and SEA in China during 2015–2030 will be easier year by year under the SSP1-1.9 scenario,while greater efforts would be required under the SSP3-7.0 pathway.The long-term(2015–2050)trend of MDA8 O_(3)concentrations in the above three regions affected by the transport from SA and SEA is similar to that of the mid-to-long term.