Abstract Ten years (2008–2017) of Black Carbon (BC) observations obtained using Aethalometer (AE-31) are analyzed to investigate the seasonal trends and temporal variabilities over a tropical site Gadanki (13.5° N, 79.2° E) located in south-east India. Diurnal variations of BC have two peak structures one in the morning (∼08 IST) in all seasons and second in the evening (∼20 IST) only during the pre-monsoon (March–May). Intra-annual variation in BC indicated February and March months as the bio-mass burning with highest BC mass concentration (3000–5000 ng/m3). About 46% of air parcel back trajectories found passing across the in-land regions of southern peninsular India brining transported aerosol to the source location during pre-monsoon. The lowest BC (∼1500 ng/m3) is noticed during the monsoon months (June–September). The average BC (2200 ng/m3) represents observational site as a typical rural site. The inter-annual variability of BC did not show any significant trend. However, trends in the maximum (March) and minimum (July) BC values show statistically significant decreasing trend suggesting reduction in bio-mass burning sources during March supported by the decrease in the fire counts. Diurnal variation in the absorption angstrom exponent indicates that the morning and evening peaks are contributed by the bio-mass combustion with values above threshold of 1. However, angstrom exponent values are found below 1 during noon time of monsoon season suggesting fossil fuel contribution. Strong coupling is found between aerosol concentration and tropospheric dynamics, meteorology in addition to the sources. The present study is expected to provide valuable input to the modelers and observational physicists as BC is climate sensitive variable.

中文翻译：

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对印度半岛南部农村地区黑碳气溶胶的长期观测：动力学和气象学的作用

摘要 分析了使用 Aethalometer (AE-31) 获得的黑碳 (BC) 观测的十年 (2008-2017) 以调查位于南部的热带地区 Gadanki (13.5° N, 79.2° E) 的季节趋势和时间变化。 - 东印度。BC 的日变化有两个峰值结构，一个在所有季节的早晨（~08 IST），第二个在晚上（~20 IST）仅在季风前（3 月至 5 月）。BC 的年内变化表明 2 月和 3 月是 BC 质量浓度最高（3000-5000 ng/m3）的生物质燃烧。发现通过印度半岛南部内陆地区的大约 46% 的航空包裹返回轨迹在季风前将气溶胶运输到源位置。在季风月份（6 月至 9 月）注意到最低的 BC（~1500 ng/m3）。平均 BC (2200 ng/m3) 代表作为典型农村站点的观测站点。BC 的年际变化没有显示出任何显着的趋势。然而，最大（3 月）和最小（7 月）BC 值的趋势显示出统计上显着的下降趋势，这表明 3 月生物质燃烧源的减少受到火灾计数减少的支持。吸收埃指数的日变化表明早晨和晚上的峰值是由生物质燃烧贡献的，其值高于阈值 1。然而，在季风季节的中午时间，埃指数值低于 1，表明化石燃料的贡献。除了来源之外，还发现气溶胶浓度与对流层动力学、气象学之间存在强耦合。