Institute of Environment and Sustainable Development, Banaras Hindu University, Varanasi, India.
Urban and Regional Studies Department, Indian Institute of Remote Sensing, Dehradun, India.
Environ Pollut. 2024 Nov 1;360:124622. doi: 10.1016/j.envpol.2024.124622. Epub 2024 Jul 29.
Cross-country assessment of aerosol loading was made over several South Asian megacities using multiple high-resolution remote-sensing database to assess how aerosols vary within the city and its suburbs. Parameters sensitive to aerosol optical and microphysical properties were processed over city-core and its surrounding, separated by a buffer. Cities across the Indo-Gangetic Plain (IGP; AOD:0.52-0.72) along with Mumbai (0.47) and Bangalore (0.46) denote comparatively high aerosol loading against non-IGP cities. City-core specific AOD was invariably high compared to surrounding, however with varying gradient having robust geographical signature. Exceptions to this general trend were in Kathmandu (ΔAOD: 0.07) and Dhaka (ΔAOD: 0.01) while strong positive AOD gradient was noted in Bangalore (+0.11), Colombo (+0.08) and in Mumbai (+0.07). While all mainland cities exhibited robust intraannual variability, distinction between city-core and its surrounding AOD exhibited varying seasonality. City-specific geometric coefficient of variation indicated insignificant association with mean AOD as opposed to European and American cities. Both pixel-based and city-specific analysis revealed a strong increasing trend in AOD with highest magnitude in Varanasi and Bangalore. Aerosol sub-types based on aerosols' sensitivity to UV-absorption and particle size denotes higher relative abundance of carbonaceous smoke aerosols within city-core, without having significant distinction for mineral dusts and urban aerosols.
利用多个高分辨率遥感数据库对南亚几个特大城市的气溶胶负荷进行了跨国评估，以评估气溶胶在城市及其郊区内的变化情况。对城市核心区及其周围地区（用缓冲区隔开）的气溶胶光学和微物理特性敏感参数进行了处理。恒河平原（IGP；AOD：0.52-0.72）沿线的城市以及孟买（0.47）和班加罗尔（0.46）的气溶胶负荷相对较高。与非 IGP 城市相比，城市核心区的 AOD 始终高于周边地区，但梯度变化具有明显的地理特征。这种总体趋势的例外是加德满都（ΔAOD：0.07）和达卡（ΔAOD：0.01），而班加罗尔（+0.11）、科伦坡（+0.08）和孟买（+0.07）则出现了强烈的正 AOD 梯度。虽然所有大陆城市都表现出很强的年内可变性，但城市核心区和周边地区的 AOD 之间的区别表现出不同的季节性。城市特定的几何系数变化表明，与欧洲和美洲城市相比，与平均 AOD 没有显著关联。基于像素和城市特定的分析都揭示了 AOD 呈强烈的上升趋势，其中瓦拉纳西和班加罗尔的幅度最大。基于气溶胶对紫外线吸收和粒径的敏感性的气溶胶亚型表示，在城市核心区，碳质烟尘气溶胶的相对丰度较高，而矿物粉尘和城市气溶胶则没有明显区别。
