17 April 2017

Pollution Particles from Open-Land Fires Have Global Impact on Clouds and Radiation

Researchers used global simulations to understand the climate impact of open-fire aerosol particles.


Atmospheric aerosol particles emitted from open-land fires could significantly affect the Earth’s energy balance, the weather, and climate. A research team, including scientists from the U.S. Department of Energy’s Pacific Northwest National Laboratory (PNNL), investigated these effects using ensemble Community Atmosphere Model 5 (CAM5) simulations performed with and without open-fire emissions.


Much is unknown about the feedback mechanisms between open fire and climate interactions. In this study, researchers reduced these uncertainties by quantifying the energy imbalance due to fire aerosols.


Researchers found fire aerosols have a significant impact on the global annual mean net radiation at the top of the atmosphere (-0.70 W m-2). They found stronger fire aerosol effects on radiation in the Northern Hemisphere high-latitude regions than in other regions (e.g., the tropics) despite a smaller quantity of fire aerosols. The study showed that the large cloud liquid water path (the amount of liquid water between two points in the atmosphere) and low solar zenith angle (the angle measurement between 90 degrees vertical [zenith] and the center of the sun) in Northern Hemisphere high-latitude regions caused strong fire aerosol effects during summer. Researchers also found significant surface cooling, precipitation reduction, and increasing amounts of low-level clouds in the Arctic summer as a result of the fire particles’ interaction with clouds. The study showed a relatively small global annual mean surface-albedo (the proportion of the incident radiation that is reflected by a surface) effect over land areas, mainly due to the fire soot-in-snow effect, with the maximum albedo effect occurring in the spring when snow starts to melt.

Yun Qian
Pacific Northwest National Laboratory (PNNL)