Postdoctoral Fellow
Department of Atmospheric and Oceanic Sciences
Peking University
Jun-Wei Xu
Recent Projects
My research applies computer models, satellite remote sensing, ground-based and aircraft measurements to understand air pollution and climate change, and their impacts on human health. The followings are my recent research projects
Climate Change - Impact of future wildfires on air quality and health
Wildfires are large sources of PM2.5 in the United States. The size and frequency of wildfires in the western U.S. have been increasing due to climate change. The trend is expected to continue throughout the 21st century, by then smoke could become the dominant source of PM2.5 in the western U.S. during the fire season. However, estimating future fire emissions and their impact on air quality is challenging.
In this study, we estimate future wildfire emissions of aerosols under different climate change scenarios (RCP 4.5 and RCP 8.5) through 2100, and further estimate the impacts on air pollution, human health and the economy. This work is an exciting collaboration with a group of excellent atmospheric scientists, epidemiologists, economists, consulting companies and the federal government of the U.S. I am leading the air quality assessment. Results from this study will be developed into the authoritative U.S. National Climate Assessment report.
Health impacts - Simulation of the oxidative potential of PM2.5
Bates et al., EST, 2019
A growing number of studies have suggested that the oxidative potential (OP) of fine particulate matter (PM2.5) may be useful in assessing the health effects of air pollution, because OP is an effective integration of biologically relevant properties of PM2.5, such as size and chemical composition. However, the spatial distribution of PM2.5 OP that epidemiological studies rely on is not yet available.
In collaboration with McGill University and Health Canada, we explore the potential of a chemical transport model (GEOS-Chem) to estimate the distribution of PM2.5 OP over North America at a fine resolution (roughly 25km x 30km)
Model development - Simulation of trace metals in PM2.5
The lack of knowledge on trace metal distributions in the atmosphere limits our understanding of the health impacts of air pollution and the metal-catalyzed formation of air pollutants.
In collaboration with the U.S. Environmental Protection Agency (EPA) and Health Canada, we filled the knowledge gap through developing the first simulation of airborne trace metals using an atmospheric chemistry model (GEOS-Chem) over North America. Results from this work will facilitate the health impact assessment of metals in PM2.5 and will enhance our understanding of metals-catalyzed formation of air pollutants.
For more information, please check out:
Xu, J.-W., Martin, R. V., Henderson, B. H., Meng J., Hand, J. L., Strum, M., Phillips, S. B.: Simulation of trace metals in fine particulate matter using the GEOS-Chem model, Atmos. Env., doi:10.1016/j.atmosenv.2019.116883, 2019. [Link]
Simulated metal distributions over North America
Arctic Warming - Sources of Arctic black carbon
As we all know that the Arctic warming is caused by greenhouse gases. But what is less known is that, soot, also known as black carbon (BC), is the second largest contributor to Arctic warming, only after CO2.
Emission sources of BC are human activities and forest fires, but none of them are present in the Arctic, then where does Arctic BC come from?
In collaboration with the University of Toronto the AWI institute in Germany, we interpreted new aircraft (NETCARE & PAMARCMiP campaigns) and surface measurements in Arctic using the GEOS-Chem model. We revealed that that Asia was the largest source of BC in the Arctic.
Geographical sources of Arctic BC at vertical levels
For more information, please check out:
Xu, J.-W. et al.: Source attribution of Arctic black carbon constrained by aircraft and surface measurements, Atmos. Chem. Phys., 17, 11971-11989, 2017. [Link]
Air Quality: satellite-derived PM2.5 over eastern China
Satellite remote sensing is commonly used in air quality studies, but geostationary satellite is rare. In collaboration with the science team of the first geostationary satellite for air quality (named GOCI) launched by Korea, we are exciting to we investigate the capability of geostationary satellite instrument in the application of air pollution. Here,
we use aerosol optical depth (AOD) from GOCI instrument, combined with the GEOS-Chem chemical transport model to estimate ground-level PM2.5 concentrations and its chemical composition over eastern China. It helps us visualize the level of pollution and its chemical composition in the most polluted region in China at high accuracy
For more information, please check out:
Xu, J.-W. et al.: Estimating ground-level PM2.5 in eastern China using aerosol optical depth determined from the GOCI satellite instrument, Atmos. Chem. Phys., 15, 13133-13144, doi:10.5194/acp-15-13133-2015, 2015. [Link]
GOCI-dervied PM2.5 concentrations over eastern China for 2010
Chemical composition of GOCI-dervied PM2.5 concentrations over eastern China for 2010