DST-Mahamana Centre of Excellence in Climate Change Research, Banaras Hindu University, Varanasi, India.
Institute of Environment and Sustainable Development, Banaras Hindu University, Varanasi, India.
Environ Pollut. 2020 Feb;257:113377. doi: 10.1016/j.envpol.2019.113377. Epub 2019 Oct 16.
Attenuated backscatter profiles retrieved by the space borne active lidar CALIOP on-board CALIPSO satellite were used to measure the vertical distribution of smoke aerosols and to compare it against the ECMWF planetary boundary layer height (PBLH) over the smoke dominated region of Indo-Gangetic Plain (IGP), South Asia. Initially, the relative abundance of smoke aerosols was investigated considering multiple satellite retrieved aerosol optical properties. Only the upper IGP was selectively considered for CALIPSO retrieval based on prevalence of smoke aerosols. Smoke extinction was found to contribute 2-50% of the total aerosol extinction, with strong seasonal and altitudinal attributes. During winter (DJF), smoke aerosols contribute almost 50% of total aerosol extinction only near to the surface while in post-monsoon (ON) and monsoon (JJAS), relative contribution of smoke aerosols to total extinction was highest at about 8 km height. There was strong diurnal variation in smoke extinction, evident throughout the year, with frequent abundance of smoke particles at lower height (<4 km) during daytime compared to higher height during night (>4 km). Smoke injection height also varied considerably during rice (ON: 0.71 ± 0.65 km) and wheat (AM: 2.34 ± 1.34 km) residue burning period having a significant positive correlation with prevailing PBLH. Partitioning smoke AOD against PBLH into the free troposphere (FT) and boundary layer (BL) yield interesting results. BL contribute 36% (16%) of smoke AOD during daytime (nighttime) and the BL-FT distinction increased particularly at night. There was evidence that despite travelling efficiently to FT, major proportion of smoke AOD (50-80%) continue to remain close to the surface (<3 km) thereby, may have greater implications on regional climate, air quality, smoke transport and AOD-particulate modelling.
利用搭载在 CALIPSO 卫星上的星载主动激光雷达 CALIOP 反演的消光后向散射廓线，测量了烟羽气溶胶的垂直分布，并将其与南亚印度-恒河平原（IGP）烟羽主导区的 ECMWF 行星边界层高度（PBLH）进行了比较。最初，根据多颗卫星反演的气溶胶光学特性，研究了烟羽气溶胶的相对丰度。仅基于烟羽气溶胶的存在，选择性地对 IGP 上部进行了 CALIPSO 反演。发现消光对总气溶胶消光的贡献为 2-50%，具有强烈的季节性和海拔属性。在冬季（DJF），烟羽气溶胶仅在近地面附近就贡献了总气溶胶消光的近 50%，而在后季风（ON）和季风（JJAS）期间，烟羽气溶胶对总消光的相对贡献在约 8km 高度最高。烟羽气溶胶的消光存在强烈的日变化，全年都很明显，白天在较低高度（<4km）频繁出现烟羽粒子，而夜间（>4km）在较高高度频繁出现烟羽粒子。在水稻（ON：0.71±0.65km）和小麦（AM：2.34±1.34km）残茬燃烧期间，烟羽注入高度也有很大变化，与盛行的 PBLH 呈显著正相关。将烟羽 AOD 与 PBLH 划分为自由大气（FT）和边界层（BL），得出了有趣的结果。BL 在白天（夜间）贡献了烟羽 AOD 的 36%（16%），BL-FT 区分度在夜间尤其增加。有证据表明，尽管烟羽气溶胶有效地传输到 FT，但大部分烟羽 AOD（50-80%）仍靠近地面（<3km），从而对区域气候、空气质量、烟羽传输和 AOD-颗粒物建模可能具有更大的影响。
