In this study year-round (2013) measurements of surface black carbon (BC) mass concentration recorded using a seven-channel Aethalometer (AE-31) over a tropical semi-urban site in Nagpur, in central India are presented. The annual mean BC during the studied period was 3.64 ± 1.81 μg m⁻³, which is comparable to that observed at few Indian and international sites. Seasonal variability in BC concentration with maximum values during the winter (4.86 ± 2.3 μgm^-3) and minimum in the monsoon (2.3 ± 0.7 μg m⁻³) season and moderate (~3.7 μg m⁻³) during the pre and post monsoon seasons was observed. The diurnal variation of BC concentration shows two peaks, one in the morning (07:00–08:00 h local time (LT)) and other prominent peak in the evening hours (19:00–21:00 h LT), with a minimum peak in the afternoon (~16:00 h LT), which could be associated with diurnal variation in local sources, boundary-layer dynamics and synoptic meteorology. The relationship between measured BC concentration and the meteorological parameters for the study location reveals a positive (negative) correlation with the mean diurnal range of air temperature (relative humidity, wind speed and rainfall). The estimated monthly mean absorption Angstrom exponent values range from 0.87 to 1.13 suggesting the change in the sources from fossil-fuel burning in the monsoon and post-monsoon periods to biomass burning in the winter and pre-monsoon. The concentration weighted trajectories analysis suggests that the potential source regions contributing to the observed BC concentration change seasonally and are positioned in the north, northwest of the observational site and in central India.

中文翻译：

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印度城市黑炭气溶胶的季节性特征：使用浓度加权轨迹的来源分析

在本研究中，全年（2013年）提供了使用七通道烟气测量仪（AE-31）在印度中部那格浦尔的一个热带半城市站点上记录的表面黑碳（BC）质量浓度的测量值。在研究期间，年平均BC为3.64±1.81μgm ^-3，与印度和国际上很少的站点所观察到的相当。在冬季在BC浓度的最大值季节变化（4.86±2.3μgm ^-3）和最小季风（2.3±0.7微克米^-3）季节和中度（〜3.7微克米^-3）在季风前后季节被观察到。BC浓度的昼夜变化有两个峰值，一个在早晨（当地时间（07：00–08：00）（LT）），另一个在晚上（19：00–21：00（当地时间），LT）显着。下午（约LT 16:00 h）的最低峰值，可能与当地来源，边界层动态和天气气象的日变化有关。研究地点测得的BC浓度与气象参数之间的关系揭示了与气温平均日范围（相对湿度，风速和降雨量）的正（负）相关。估计的每月平均吸收埃指数范围为0.87至1。13表明从季风和季风后的化石燃料燃烧到冬季和季风前的生物质燃烧的来源变化。浓度加权轨迹分析表明，导致观测到的BC浓度的潜在源区随季节变化，并且位于观测点的北部，西北部和印度中部。