测量由生物质燃烧引起的气溶胶

作者：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)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,收集数据16个月为了帮助了解这些空气传播颗粒如何影响气候。

Better data needed in climate models

Biomass burning (BB) produces aerosols that enter the atmosphere. A significant amount of this particulate matter consists of black carbon and other carbonaceous aerosols that absorb light, warming the atmosphere; however, if the underlying surface is a dark ocean, the particles reflect light, cooling the atmosphere.科学家需要准确的测量of each type of aerosol in the layers of the atmosphere to研究烟雾的运动和长期后果.

目前，在全球气候模型中，远离来源的BB气溶胶层的垂直范围很差。为了帮助改善模型，ARM为2016年6月至2017年10月在Ascension Island上的云层（LASIC）运动中部署了其中一个与云层（LASIC）运动的分层烟雾相互作用的移动大气观测站。约1,000英里。（1,609公里）在非洲西海岸。从这个独特的位置，研究人员从众多仪器中录制了测量，以编译一个代表两个BB季节的综合数据集。

用于激光研究的微脉冲激光雷达

升天岛上的手臂移动设施

ARM launched the LASIC campaign specifically 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。”

从MPL观测的一天（2018-08-15）的灭绝曲线显示，在21小时内，下沉的烟雾层从00时约2.8 km到21小时的大约1.8 km。

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.

对检索到的灭绝配置文件的月度变化的分析提供了首次查看。进化'BB和BB季节的气溶胶垂直结构以及升天岛上的烟层深度升高。在南部非洲燃烧季节（10月至10月）期间，大量影响地球能量平衡和云特性的气溶胶在海洋边界层中很常见。

The MPL data shows thesmoke layer is present mostly above boundary layercloudsbetween 1.5 to 3 km在7月的燃烧季节开始时extends 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.

“在激光期间收集的数据提高了我们目前对气溶胶垂直分布及其辐射影响的理解，”LASIC运动的首席研究员Paquita Zuidema说。“这最终将导致长期气候预测的准确性提高，并帮助我们开发能源和环境挑战的可持续解决方案。”

Elevating atmospheric monitoring

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仪器可帮助科学家，气象学家和空气质量专业人士监视气溶胶，以更好地了解我们的气氛结构。MPL的远程功能和高质量信号提高了数据捕获过程的效率和准确性，以改善大气监测。MPL最初由Sigma Space为NASA设计，现在是Hexagon的一部分，使用了眼部安全激光器，精密光子计数bob体育报道和内置数据分析来提供最佳的信噪比，从而提供了此类别中最可靠的信息。