Aerosol chemistry, transport and climatic implications during extreme biomass burning emissions over Indo-Gangetic Plain
Aerosol chemistry, transport and climatic implications during extreme biomass burning emissions over Indo-Gangetic Plain
复制标题
DOI：
10.5194/acp-2018-446
复制
发表时间：
2018-06
期刊：
影响因子：
--
通讯作者：
Nandita Singh;T. Banerjee;M. Prudhvi Raju;K. Deboudt;M. Sorek-Hamer;R. Singh;R. Mall
中科院分区：
文献类型：
--
作者：
Nandita Singh;T. Banerjee;M. Prudhvi Raju;K. Deboudt;M. Sorek-Hamer;R. Singh;R. Mall
摘要。农业废弃物焚烧产生的空气中颗粒物的大规模排放，特别是在印度河-恒河平原上游（IGP）上空，往往与雾霾的频繁形成、对健康的不利影响、气溶胶气候学的改变以及气溶胶对区域气候的影响有关。在本研究中，研究了IGP上极端生物质燃烧排放期间气溶胶气候学的短期变化，从而对区域气候进行了研究。最初测量了尺寸分离的颗粒浓度，发现亚微米颗粒（PM1.1）在细模式（PM2.1）中占主导地位。颗粒结合水溶性离子在自然界中主要是次生的，主要由硫酸盐和硝酸盐组成。有证据表明，在亚微米颗粒中，气态NH3主导酸性气溶胶（SO42−）的中和作用，而在粗颗粒中，地壳主导中和作用。发现黑碳质量比的变化受局部源的影响，而浓度的突然增加与高δ - c一致，指的是生物源排放。利用特定的有机（左旋葡聚糖）、无机（K+和NH4+）和卫星（UV气溶胶指数，UVAI）示踪剂确定生物质燃烧排放的影响。在亚微米颗粒中，左旋葡聚糖含量最高（649±177 ng m−3），与其他无水糖的比值非常高（bbb50），表明仅由农业废弃物燃烧排放。所有示踪剂的时间变化是一致的，而NH4+与左旋葡聚糖的关系更为密切。利用星载主动和被动传感器对气溶胶和少量微量气体（CO和NO2）的时空分布进行了评估，结果表明，在极端生物质燃烧排放期间，柱状气溶胶负荷（AOD: 0.98）显著增加，且气溶胶层高度（~1.5 km）较低的吸收气溶胶（UVAI > 1.5）存在。CALIPSO甚至注意到气溶胶横切面高度剖面具有很强的季节性，指的是烟雾和污染的大陆气溶胶在IGP中的主导地位。利用聚类分析和气团反轨迹浓度加权，建立了生物质烟雾可能的输运机制。考虑气溶胶特性的季节性，进一步模拟了短波气溶胶辐射强迫（ARF），结果表明，与非主导排放（56 Wm−2,1.8 K day−1）相比，极端生物质燃烧排放期间大气ARF （135 Wm−2）和升温速率（4.3 K day−1）显著增加。因此，我们认为必须在更精细的尺度上研究生物质燃烧排放对区域气溶胶气候学的影响，以改进整个区域气溶胶/气候模式的参数化。
Abstract. The large-scale emissions of airborne particulates from burning of agricultural residues particularly over the upper Indo-Gangetic Plain (IGP) have often been associated with frequent formation of haze, adverse health impacts, modification in aerosol climatology and thereby aerosols impact on regional climate. In this study, short-term variations in aerosol climatology during extreme biomass burning emissions over IGP, and thereby to regional climate were investigated. Size-segregated particulate concentration was initially measured and submicron particles (PM1.1) were found to dominate particulate mass within the fine mode (PM2.1). Particulate bound water-soluble ions were mainly secondary in nature, primarily composed of sulfate and nitrate. There was evidence of gaseous NH3 dominating neutralization of acidic aerosol species (SO42−) in submicron particles, in contrast to crustal dominating neutralization in coarser particulates. Variation in black carbon mass ratio was found to be influenced by local sources, while sudden increase in concentration was consistent with high Delta-C, referring to biogenic emissions. Influence of biomass burning emissions were established using specific organic (levoglucosan), inorganic (K+ and NH4+) and satellite (UV Aerosol Index, UVAI) tracers. Levoglucosan was the most abundant within submicron particles (649±177 ng m−3), with a very high ratio (>50) against other anhydrosugars, indicating exclusive emissions from burning of agriculture residues. Temporal variations of all the tracers were consistent, while NH4+ was more closely associated to levoglucosan. Spatio-temporal distribution of aerosol and few trace gases (CO and NO2) were evaluated using both space-borne active and passive sensors, and a significant increase in columnar aerosol loading (AOD: 0.98) was evident during extreme biomass burning emissions, with presence of absorbing aerosols (UVAI > 1.5) having low aerosol layer height (~1.5 km). A strong intraseasonality in aerosol cross-sectional altitudinal profile was even noted from CALIPSO, referring dominance of smoke and polluted continental aerosols across IGP. Possible transport mechanism of biomass smoke was established using cluster analysis and concentration weighted of air mass back-trajectories. Short-wave aerosol radiative forcing (ARF) was further simulated considering intraseasonality in aerosol properties, which resulted in considerable increase of atmospheric ARF (135 Wm−2) and heating rate (4.3 K day−1) during extreme biomass burning emissions compared to non-dominating one (56 Wm−2, 1.8 K day−1). We therefore conclude that influence of biomass burning emissions on regional aerosol climatology must need to be studied in much finer scale to improve parameterization of aerosol/-climate model across the region.