Institute of Environment and Sustainable Development, Banaras Hindu University, Varanasi, India.
Institute of Environment and Sustainable Development, Banaras Hindu University, Varanasi, India; DST-Mahamana Centre of Excellence in Climate Change Research, Banaras Hindu University, Varanasi, India.
Sci Total Environ. 2022 Oct 10;842:156834. doi: 10.1016/j.scitotenv.2022.156834. Epub 2022 Jun 21.
Three-dimensional (temporal-spatial-vertical) climatology of South Asian summertime (MAMJ, 2010-2019) aerosols and aerosol sub-types was explored using multiple high-resolution satellite-based observations and reanalysis dataset. Vertical stratification of aerosol layer and aerosol sub-types was identified using observation from space-borne lidar. Aerosol optical depth (AOD) was particularly high across the Indo-Gangetic Plain (IGP; AOD ± SD: 0.56 ± 0.12) and over eastern coast of India (AOD: 0.6-0.8), with prevalence of heterogeneous aerosol sub-types having strong spatial gradient. Clearly, aerosols over north-western arid part were highly absorbing (Ultra-violet Aerosol Index, UVAI > 0.80) and coarse (Ångström exponent, AE < 0.8), with an indication of desert/-mineral dust aerosols. In contrast, fine and moderate to non-absorbing aerosols (UVAI: 0.20-0.50) dominate from central to lower IGP, including in Bangladesh, with signature of anthropogenic emissions. Prevailing aerosols over twelve South Asian cities were classified into six aerosol sub-types constraining their particle size and UV-absorbing potential. Overall, mineral dust, smoke and urban aerosols were the three major aerosol sub-types that prevail across South Asia during summer. In particular, 58-70 % of retrieval days over Karachi and Multan were dust dominated; 57-64 % days were dust or urban aerosols dominated over Lahore, Delhi, Kanpur and Varanasi, and 56-77 % days were smoke or urban aerosols dominated over Dhaka, Kathmandu, Chennai, Mumbai, Colombo and Nagpur. Prevailing aerosols were vertically stratified as 50-70 % of total AOD was retrieved <2 km from the surface except in few cities where 70-80 % of AOD was retrieved <3 km height. Mineral dust and/or urban aerosols emerged as the most abundant aerosol types near the surface (<1 km) in all the cities except in Chennai, with their abundance remained as a function of emission sources and geographical location.
利用多颗高分辨率卫星观测和再分析数据集，研究了 2010-2019 年南亚夏季（MAMJ）气溶胶及其子类型的三维（时空垂直）气候特征。利用星载激光雷达的观测结果，确定了气溶胶层和子类型的垂直分层。整个印度河平原（IGP；AOD±SD：0.56±0.12）和印度东海岸（AOD：0.6-0.8）上空的气溶胶光学厚度（AOD）特别高，具有强烈空间梯度的多相气溶胶子类型普遍存在。显然，西北部干旱地区上空的气溶胶具有很强的吸收性（紫外气溶胶指数，UVAI>0.80）和粗粒性（Angstrom 指数，AE<0.8），表明存在沙漠/矿物尘气溶胶。相比之下，从中部到下 IGP 地区，细颗粒和中等至非吸收性气溶胶（UVAI：0.20-0.50）占主导地位，包括孟加拉国在内，这表明存在人为排放。对 12 个南亚城市的气溶胶进行分类，得到了 6 种气溶胶子类型，它们限制了气溶胶的粒径和紫外吸收能力。总体而言，矿物尘、烟雾和城市气溶胶是夏季南亚地区普遍存在的三种主要气溶胶子类型。特别是，卡拉奇和木尔坦 58-70%的回波天数以尘源为主；拉合尔、德里、坎普尔和瓦拉纳西 57-64%的回波天数以尘源或城市气溶胶为主，达卡、加德满都、钦奈、孟买、科伦坡和那格浦尔 56-77%的回波天数以烟雾或城市气溶胶为主。盛行的气溶胶在垂直方向上分层，总 AOD 的 50-70%在离地面 2 公里以下的地方被探测到，除了少数城市外，70-80%的 AOD 在离地面 3 公里以下的地方被探测到。除钦奈外，所有城市在近地面（<1 公里）的最丰富气溶胶类型均为矿物尘和/或城市气溶胶，其丰度取决于排放源和地理位置。
