This paper investigates the impacts on aerosol characteristics, optical and radiative properties due to a mesoscale dust storm which originated from the Arabian, Iran/Pakistan region and observed to pass in vicinity over the semiarid region of Western India in April, 2017. The extent and long-distance transport of dust along with varying aerosol optical depth (AOD) were studied with high spatial and temporal resolution space-based observations. In situ measurements of particulate matter (PM) indicated high dust loading with PM10 and PM2.5 concentrations as high as 223 and 253 µg/m³ and 142.6 and 160 µg/m³, respectively. High concentrations of Inhalable, thoracic and alveolic PM aerosols (~ 290, 200 and 100 µg/m3, respectively) are also observed due to high dust load in the atmosphere, that is hazardous to human health, particularly for people suffering from respiratory ailments. The fine-mode fraction and Angstrom exponent have also been analyzed using satellite data. Satellite-derived AOD and in situ meteorological data were used as model inputs to estimate the radiative forcing impact of dust aerosols using a coupled radiative transfer model. The radiative transfer model simulations results indicate a reduction in the total downward surface flux by 6.5%, 6.7%, 5.0%, 10.1%, 7.1%, 8.9%, 3.7% and 5.3% as height decreases from 5 to 0 km (surface) during pre- to post-dust storm event period, respectively. The aerosols vertical profiles obtained from spaceborne CALIPSO LiDAR validated the predominant presence of “dust” aerosols during this event. The study provides important quantitative insights into extreme variabilities in aerosol properties resulting to a “cooling effect” during a severe mesoscale dust storm event over a semiarid region.

本文研究了 2017 年 4 月起源于阿拉伯、伊朗/巴基斯坦地区并在附近经过印度西部半干旱地区的中尺度沙尘暴对气溶胶特征、光学和辐射特性的影响。通过高空间和时间分辨率的天基观测研究了灰尘的长距离传输以及气溶胶光学深度（AOD）的变化。颗粒物 (PM) 的原位测量表明，PM10 和 PM2.5 浓度高达 223 和 253 µg/m ³以及 142.6 和 160 µg/m ^{3 的}高粉尘负荷， 分别。由于大气中的高粉尘载量，也观察到高浓度的可吸入、胸部和肺泡 PM 气溶胶（分别为约 290、200 和 100 µg/m3），这对人类健康有害，特别是对患有呼吸系统疾病的人。还使用卫星数据分析了精细模式分数和埃指数。卫星衍生的 AOD 和原位气象数据被用作模型输入，以使用耦合辐射传输模型估计尘埃气溶胶的辐射强迫影响。辐射传输模型模拟结果表明，随着高度从 5 公里（表面）降低到 0 公里，总向下表面通量减少了 6.5%、6.7%、5.0%、10.1%、7.1%、8.9%、3.7% 和 5.3%分别在沙尘暴事件前后。从星载 CALIPSO LiDAR 获得的气溶胶垂直剖面证实了此次事件中“灰尘”气溶胶的主要存在。该研究为气溶胶特性的极端变化提供了重要的定量见解，这些变化在半干旱地区发生严重的中尺度沙尘暴事件期间导致“冷却效应”。