Satellite-based observations of formaldehyde (HCHO) in wildfire plumes

Trace gases and aerosols emitted from wildfires can significantly influence the earth's climate, the composition of the atmosphere, as well as air quality and human health. Various satellite data, such as carbon monoxide (CO), nitrogen dioxide (NO₂), and aerosol index (AI) have been used to estimate the impacts of wildfire emissions and evolution of wildfire plumes. However, relatively few studies have taken advantage of the global observations of formaldehyde (HCHO) from satellites. Despite its relatively short lifetime, HCHO is an intermediate product of volatile organic compounds (VOCs) oxidations that are closely linked to the formation of troposphere ozone and organic aerosols. The evolution if HCHO loading in wildfire plumes with time may provide information on the chemical processes within wildfire plumes during long-range transport.

In this presentation, we use multiple satellite-based datasets to study the evolution of wildfire plumes. In particular, we retrieve the column amount of HCHO in smoke plumes from large wildfires in different regions, e.g., Southeast Asian, Siberia, tropical Africa, and the Amazon, by applying a principal component analysis (PCA) retrieval technique to the Dutch/Finnish Ozone Monitoring Instrument (OMI) on NASA Aura satellite. We identify and track the wildfire plumes as they travel away from the sources, and quantify the changes in HCHO as well as aerosols, CO, and NO₂. We also investigate the uncertainties in HCHO retrievals for wildfire plumes due to interfering effects of smoke aerosols. Finally, we discuss the implication of this study pertaining to the large-scale impacts of wildfire plumes on atmospheric composition, particularly over remote areas.