Polarization lidar observations were made to study the transport of an elevated aerosol layer over Gadanki, India (13.45° N, 79.17° E) during the pre-monsoon period of the year 2009. Observations show significant aerosol layering within and above the boundary layer. Coordinated observations with radiosondes were carried out from 2 to 10 April 2009. Temporal and spatial variations of the parameters are studied for the boundary layer (≈ 2.5 km) and up to 5 km. The backscattering coefficient and the depolarization ratio are observed to increase and decrease with an increase in humidity, respectively. Clouds are not formed, indicating less efficiency of the aerosol in acting as condensation nuclei. The transport of the elevated aerosol layer is investigated using a back-trajectory analysis, revealing that the transported layer originating from the central Indian region has a depolarization ratio of at least 0.05. From model analysis and satellite fire-count data, it is inferred that the source of the aerosol layer is wildfire events over the central Indian region. The elevated smoke-aerosol layer (not mixing with the boundary layer) has implications for the altering of the temperature profile of the atmosphere and the suppression of cloud formation.

中文翻译：

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使用偏振激光雷达在印度热带农村地区调查升高的气溶胶层

进行了偏振激光雷达观测，以研究 2009 年季风前期期间在印度加丹基（北纬 13.45°，东经 79.17°）上空升高的气溶胶层的传输。观测显示边界层内和边界层上方有明显的气溶胶分层。2009 年 4 月 2 日至 10 日使用无线电探空仪进行了协调观测。研究了边界层（≈ 2.5 公里）和长达 5 公里的参数的时空变化。观察到背向散射系数和去极化率分别随着湿度的增加而增加和减少。没有形成云，表明气溶胶作为凝结核的效率较低。使用反向轨迹分析研究升高的气溶胶层的传输，揭示源自印度中部地区的传输层的去极化率至少为 0.05。从模型分析和卫星火灾计数数据推断，气溶胶层的来源是印度中部地区的野火事件。升高的烟雾气溶胶层（不与边界层混合）对改变大气温度剖面和抑制云形成具有影响。