Understanding the Effects of Biomass Burning on the Climate

Micro Pulse LiDAR (MPL) is being used to study the vertical extent and movement of aerosols in the atmosphere caused by traditional biomass burning (BB) in southern Africa.

Every year from June to October, large swaths of agricultural land are burned to clear debris before the next growing season in southern Africa. Smoke from this activity blows westward across the Atlantic Ocean to reach as far as Brazil 4,500 miles away.

Researchers at the Atmospheric Radiation Measurement (ARM) user facility, operated by the U.S. Department of Energy on the remote island of Ascension, launched the Layered Atlantic Smoke Interactions with Clouds (LASIC) campaign to gather data about the type and quantity of aerosols found in this smoke and the smoke’s effect on clouds and the climate.

To incorporate the effects of BB into global climate models, better data were needed about the vertical structure and the monthly and seasonal variations of the BB aerosol layers. While aerosol surface measurements were available from multiple instruments, it was important to include profiling instrumentation that could discriminate between smoke, dust and sea salt aerosol layers many kilometers above the surface.

At the mobile atmospheric observatory on Ascension Island data were collected for 16 months with an MPL and other instruments. The dual-polarization capability of the MPL successfully provided vertical aerosol profiles throughout two BB seasons. Programmed for continuous operation, the rugged MPL system was well suited to the lengthy project.

The unique location on Ascension Island provided an excellent dataset to improve the current understanding of aerosol vertical distribution and the radiative impact on the climate. The collected data show high amounts of aerosols in the marine boundary layer during the southern Africa burning season. Further study will help researchers better understand how these particles affect the Earth’s cloud properties and improve the accuracy of long-term climate forecasts.

For more information about the Ascension Island research project, visit https://www.arm.gov/research/campaigns/amf2016lasic