Miller Rose M, McFarquhar Greg M, Rauber Robert M, O'Brien Joseph R, Gupta Siddhant, Segal-Rozenhaimer Michal, Dobracki Amie N, Sedlacek Arthur J, Burton Sharon P, Howell Steven G, Freitag Steffen, Dang Caroline
Department of Atmospheric Science, University of Illinois Champaign-Urbana, Urbana, IL, USA.
Cooperative Institute of Mesoscale Meteorological Studies, University of Oklahoma, Norman, OK, USA.
Atmos Chem Phys. 2021 Sep;21(19):14815-14831. doi: 10.5194/acp-21-14815-2021. Epub 2021 Oct 6.
During the 3 years of the ObseRvations of Aerosols above CLouds and their intEractionS (ORACLES) campaign, the NASA Orion P-3 was equipped with a 2D stereo (2D-S) probe that imaged particles with maximum dimension () ranging from 10 < < 1280 μm. The 2D-S recorded supermicron-sized aerosol particles (SAPs) outside of clouds within biomass burning plumes during flights over the southeastern Atlantic off Africa's coast. Numerous SAPs with 10 < < 1520 μm were observed in 2017 and 2018 at altitudes between 1230 and 4000 m, 1000 km from the coastline, mostly between 7-11° S. No SAPs were observed in 2016 as flights were conducted further south and further from the coastline. Number concentrations of refractory black carbon (rBC) measured by a single particle soot photometer ranged from 200 to 1200 cm when SAPs were observed. Transmission electron microscopy images of submicron particulates, collected on Holey carbon grid filters, revealed particles with potassium salts, black carbon (BC), and organics. Energy-dispersive X-ray spectroscopy spectra also detected potassium, a tracer for biomass burning. These measurements provided evidence that the submicron particles originated from biomass burning. NOAA Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) 3 d back trajectories show a source in northern Angola for times when large SAPs were observed. Fire Information for Resource Management System (FIRMS) Moderate Resolution Imaging Spectroradiometer (MODIS) 6 active fire maps showed extensive biomass burning at these locations. Given the back trajectories, the high number concentrations of rBC, and the presence of elemental tracers indicative of biomass burning, it is hypothesized that the SAPs imaged by the 2D-S are examples of BC aerosol, ash, or unburned plant material.
在“云上海洋气溶胶及其相互作用观测（ORACLES）”活动的3年期间，美国国家航空航天局（NASA）的猎户座P - 3飞机配备了二维立体（2D - S）探头，该探头可对最大尺寸（）在10＜＜1280微米范围内的颗粒进行成像。在飞越非洲海岸附近东南大西洋的飞行过程中，2D - S记录了生物质燃烧羽流中云外的超微米级气溶胶颗粒（SAPs）。2017年和2018年，在距离海岸线1000公里、海拔1230至4000米、主要在南纬7 - 11°之间观测到大量尺寸在10＜＜1520微米的SAPs。2016年未观测到SAPs，因为飞行是在更南且离海岸线更远的地方进行的。当观测到SAPs时，用单颗粒烟尘光度计测量的难熔黑碳（rBC）数浓度范围为200至1200个/立方厘米。在带孔碳网格滤膜上收集的亚微米颗粒的透射电子显微镜图像显示，颗粒含有钾盐、黑碳（BC）和有机物。能量色散X射线光谱也检测到了钾，这是生物质燃烧的一种示踪剂。这些测量结果证明亚微米颗粒源自生物质燃烧。美国国家海洋和大气管理局（NOAA）的混合单颗粒拉格朗日积分轨迹（HYSPLIT）3天反向轨迹显示，在观测到大量SAPs的时间段，源地在安哥拉北部。资源管理系统火灾信息（FIRMS）中等分辨率成像光谱仪（MODIS）的6幅活跃火灾地图显示这些地点有大量生物质燃烧。鉴于反向轨迹、rBC的高数量浓度以及指示生物质燃烧的元素示踪剂的存在，据推测2D - S成像的SAPs是BC气溶胶、灰烬或未燃烧植物材料的实例。
