Measuring aerosols caused by biomass burning

Author:Justin Fisher

从六月到十月，南部非洲的农业田地的燃烧会造成向西吹过东南大西洋的烟雾，并到达巴西，超过4,500英里（7,242公里）away. Using Micro Pulse LiDAR (MPL) and other instruments, researchers at the Atmospheric Radiation Measurement (ARM) user facility on the remote island of Ascension, operated by the U.S. Department of Energy,collected data for 16 monthsto help understand how these airborne particles impact the climate.

气候模型中所需的更好数据

生物质燃烧（BB）产生进入大气的气溶胶。大量颗粒物由黑碳和其他吸收光线，使大气变暖的碳质气溶胶组成。但是，如果下面的表面是黑暗的海洋，则颗粒会反射光，从而冷却大气。Scientists need accurate measurements大气层中每种类型的气雾剂study the movement and long-term consequences of the smoke。

Currently, the vertical extent of the BB aerosol layers transported far from the sources is poorly represented in global climate models. To help improve the models, ARM deployed one of its mobile atmospheric observatories for the Layered Atlantic Smoke Interactions with Clouds (LASIC) campaign from June 2016 to October 2017 on Ascension Island,about 1,000 mi. (1,609 km)off the west coast of Africa. From this unique location, researchers recorded measurements from numerous instruments to compile a comprehensive dataset representing two BB seasons.

Micro Pulse LiDAR used in LASIC research

The ARM Mobile Facility on Ascension Island

ARM发起了激进的运动，专门收集有关烟雾特性（即吸收短波辐射的能力）在长期大气运输后发生变化以及烟雾对云的影响的数据。虽然可从多种仪器获得气溶胶表面测量值，以研究运送到该偏远岛的BB气溶胶层的垂直结构以及每月和季节性变化，但重要的是包括分析仪器。

“激光的关键MPL能力之一是其双极化能力，它允许歧视烟，灰尘和海盐气溶胶层上方上方，”Argonne国家实验室研究人员Paytsar Muradyan说。“此外，ARM移动设施经常被部署在世界各地的偏远地区，MPL能够提供无人看管的云和气溶胶的连续观察。”

Extinction profiles from one day of MPL observations (2018-08-15) show a sinking smoke layer over 21 hours from approximately 2.8 km at hour 00 to approximately 1.8 km at hour 21.

Raw MPL measurements consisting of profiles of backscattered signal from atmospheric particles were collected throughout the LASIC field campaign. The ARM Data Center (ADC) ingested hourly raw data along with the MPL corrections, and Climate and Forecast (CF) standardised NetCDF files were archived at the ADC to help validate results.

The analysis of the monthly variations of the retrieved extinction profiles provides a first look into the ‘evolution’of the pre-BB and BB season aerosol vertical structure and elevated smoke layer depths over Ascension Island. High amounts of aerosols that can affect the Earth’s energy balance and cloud properties are common in the marine boundary layer during the southern African burning season (June-October).

MPL数据显示烟层主要存在于边界层上方clouds在1.5至3公里之间at the beginning of the burning season in July andextends up to 4 km in September。Occurrences of the BB smoke layers coincide with the peak black carbon concentrations (>1,000 nanogram/cubic metre) observed at the surface, suggesting that these aerosols are strongly absorbing, as back trajectories indicate that they originate from the same continental BB regions.

“The data collected during LASIC improve our current understanding of aerosol vertical distribution and their radiative impact,”says Paquita Zuidema, principal investigator of the LASIC campaign.“This will ultimately lead to improved accuracy of long-term climate forecasts and help us develop sustainable solutions to energy and environmental challenges.”

提升大气监测

Smoke envelopes the first ARM Mobile Facility during a hazy day on Ascension Island, which is located in the South Atlantic Ocean.

MPL仪器帮助科学家,气象学家d air quality professionals monitor aerosols to better understand the structure of our atmosphere. MPL’s long-range capabilities and high-quality signal increase the efficiency and accuracy of the data capture process for improved atmospheric monitoring. Originally designed by Sigma Space for NASA, now part of Hexagon, MPL uses eye-safe lasers, precision photon counting, and built-in data analysis to deliver the best signal-to-noise ratio, providing the most reliable information in this category.