Wildfire Smoke Particle Properties and Evolution, from Space-Based Multi-Angle Imaging

Katherine Junghenn Noyes,Arthur Sedlacek,James Limbacher,Ralph Kahn,Zhanqing Li,Lawrence Kleinman

doi:10.3390/rs12050769

Abstract

Emitted smoke composition is determined by properties of the biomass burning source and ambient ecosystem. However, conditions that mediate the partitioning of black carbon (BC) and brown carbon (BrC) formation, as well as the spatial and temporal factors that drive particle evolution, are not understood adequately for many climate and air-quality related modeling applications. In situ observations provide considerable detail about aerosol microphysical and chemical properties, although sampling is extremely limited. Satellites offer the frequent global coverage that would allow for statistical characterization of emitted and evolved smoke, but generally lack microphysical detail. However, once properly validated, data from the National Aeronautics and Space Administration (NASA) Earth Observing System’s Multi-Angle Imaging Spectroradiometer (MISR) instrument can create at least a partial picture of smoke particle properties and plume evolution. We use in situ data from the Department of Energy’s Biomass Burning Observation Project (BBOP) field campaign to assess the strengths and limitations of smoke particle retrieval results from the MISR Research Aerosol (RA) retrieval algorithm. We then use MISR to characterize wildfire smoke particle properties and to identify the relevant aging factors in several cases, to the extent possible. The RA successfully maps qualitative changes in effective particle size, light absorption, and its spectral dependence, when compared to in situ observations. By observing the entire plume uniformly, the satellite data can be interpreted in terms of smoke plume evolution, including size-selective deposition, new-particle formation, and locations within the plume where BC or BrC dominates.

Highlights

Wildfires are significant emitters of trace gases and aerosols that impact local air quality, and they can affect regional- and global-scale radiation budgets, cloud properties, and the water cycle
The plume produced by this fire complex was observed by Multi-Angle Imaging Spectroradiometer (MISR) on 21 August 2013, at ~19:07 Universal Coordinated Time (UTC), ~2 h before the Burning Observation Project (BBOP) G-1 aircraft began sampling the same area; the aircraft continued sampling this plume for an additional hour
We calculate the approximate age of the smoke at regional boundaries using the ratio of the along-plume distance and mean wind vectors in the area derived from MISR Interactive Explorer (MINX)

Summary

Introduction

Wildfires are significant emitters of trace gases and aerosols that impact local air quality, and they can affect regional- and global-scale radiation budgets, cloud properties, and the water cycle. Smoke aerosols that escape the planetary boundary layer (PBL) have the potential to stay aloft for several days or more, altering the regional radiative budget on time scales that can extend beyond the age of the fire itself and can affect air quality hundreds of kilometers downwind [1,2]. These particles have the potential to act as cloud-condensation nuclei (CCN), resulting in aerosol–cloud interactions that can alter cloud reflectivity, cloud lifetime, and the frequency of precipitation [3,4,5,6]. The variable nature of BB particles means that smoke plume radiative and other environmental impacts are far from uniform or predictable at present, especially as the dominant factors mediating particle aging are uncertain

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