Measuring aerosols caused by biomass burning

Author:Justin Fisher

From June to October, the burning of agricultural fields in southern Africa creates smoke that blows west across the south-eastern Atlantic Ocean and reaches Brazil,more than 4,500 miles (7,242 kilometres)离开。使用微脉冲激光雷达（MPL）和其他仪器，由美国能源部运营的大气辐射测量（ARM）用户设施的研究人员，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 measurementsof each type of aerosol in the layers of the atmosphere to研究烟雾的运动和长期后果。

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

手臂LASIC活动规范ifically to gather data on how smoke properties (i.e., ability to absorb shortwave radiation) change after long-range atmospheric transport, as well as the smoke’s effect on clouds. While aerosol surface measurements were available from multiple instruments, to study the vertical structure and the monthly and seasonal variations of the BB aerosol layers transported to this remote island, it was important to include profiling instrumentation.

“One of the critical MPL capabilities for LASIC is its dual-polarisation capability, which allows discrimination of smoke, dust and sea salt aerosol layers above Ascension Island,”said Paytsar Muradyan, Argonne National Laboratory researcher.“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.

在整个激光场运动中，收集了由大气颗粒的反向散射信号曲线组成的原始MPL测量值。ARM数据中心（ADC）摄入了每小时的原始数据以及MPL校正，气候和预测（CF）标准化NETCDF文件在ADC上存档以帮助验证结果。

The analysis of the monthly variations of the retrieved extinction profiles provides a first look into the ‘进化'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).

The MPL data shows thesmoke layer is present mostly above boundary layerclouds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。BB烟层的发生与在表面观察到的黑色峰浓度（> 1,000纳米图/立方米）一致，这表明这些气溶胶非常吸收，因为背部轨迹表明它们起源于相同的大陆BB区域。

“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

在位于南大西洋的升天岛上，烟雾笼罩着第一臂移动设施。

MPL instruments help scientists, meteorologists and 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.