Final Report: Impacts of Climate-induced Changes in Extreme Events on Ozone and Particulate Matter Air Quality

EPA Grant Number: R835189
Title: Impacts of Climate-induced Changes in Extreme Events on Ozone and Particulate Matter Air Quality
Investigators: Wu, Shiliang , McCarty, Jessica
Institution: Michigan Technological University , University of Louisville
EPA Project Officer: Callan, Richard
Project Period: June 1, 2012 through May 31, 2015 (Extended to May 31, 2017)
Project Amount: $374,960
RFA: Extreme Event Impacts on Air Quality and Water Quality with a Changing Global Climate (2011) RFA Text |  Recipients Lists
Research Category: Air Quality and Air Toxics , Water Quality , Climate Change , Air , Water

Objective:

This study aims at improving our understanding and quantification of the potential effects of climate change on extreme meteorological events and air quality. Climate-induced changes in the following extreme events and their consequences for ozone and particulate matter (PM) air quality were investigated: (a) heat waves; (b) temperature inversion; (c) atmospheric stagnation; (d) lightning activities and associated wildfires.

Summary/Accomplishments (Outputs/Outcomes):

We have investigated the long-term trends in extreme air pollution meteorological events (including heat waves, temperature inversions, atmospheric stagnation, precipitation characteristics and lightning activities) in the past decades based on multiple observational datasets. We found significant increases in many of these extreme air pollution meteorological events in the past decades, especially over the continental regions (Figures 1a and 1b).

Fig. 1a. Changes in the frequency of heat waves (days/yr) in 1951-2010 (based on the NCEP reanalysis data). Left: 1951-1980 average; right: percentage change (%) between 1951-1980 and 1981-2010.  

Fig. 1b. Changes in the frequency of temperature inversions (hrs/yr) in 1951-2010 (based on the NCEP reanalysis data). Left: 1951-1980 average; right: percentage change (%) between 1951-1980 and 1981-2010.

We have analyzed in detail the potential impacts of extreme air pollution meteorological events on ozone and fine particulate matter (PM2.5) air pollutants based on observational datasets for both meteorology and air quality. One of the interesting findings is that heat waves have much stronger impacts on air quality than single “hot” days with the same temperature (Fig. 2). This reflects the build-up effects from the extended period of high temperature during heat wave events and has not been reported in previous literature on ozone-temperature responses.

Fig 3 

Fig. 2. Summer ozone concentrations as a function of daily maximum temperature based on 2001-2010 data in the United States. Blue curve shows the average ozone concentrations for all the days with temperature falling in specific temperature bins while the red curve only covers days with heat waves.

We find that extreme meteorological events can significantly enhance both the average concentrations of air pollutants (Fig. 3) and the frequency of high air pollution episodes (Fig. 4). Large seasonal and spatial variations in the sensitivities of ozone and PM air quality to extreme meteorology were identified. We found that in general, the high ozone pollution episodes in summer are most sensitive to heat waves among all the extreme meteorological events, while temperature inversion and atmospheric stagnation events are the most important factors leading to serious PM pollution in winter for the western and the eastern United States, respectively. We have also studied the impacts of wildfires on air quality in the United States. We found that during the simulated wildfire event, emissions of air pollutants from the wildfire increase the PM concentration by more than 40% in large regions of the western U.S.

Fig 2

 

Fig. 3. Enhancements in the seasonal average air pollutant concentrations by extreme meteorological events. Shown as the percentage change (%) of mean concentrations (for either ozone or PM2.5) on days with a specific meteorological event (event groups) compared to those on days without that event occurrence (no-event groups): a. ozone vs. heat waves; b. PM2.5 vs. temperature inversions; c. PM2.5 vs. atmospheric stagnation episodes. Shadowed regions indicate that the differences between the two groups are statistically non-significant at the 95% confidence interval. Blank regions indicate those with less than 3 data points for either group.

 

 

Fig 5

Fig. 4. Enhancements in the probability of high pollution episodes by extreme air pollution meteorological events for different states and regions in the United States. Shown as the impact factor for (a) summer ozone by state; (b) summer ozone by region; (c) winter PM2.5 by state; and (d) winter PM2.5 by region associated with various meteorological events (heat waves, temperature inversions and atmospheric stagnation episodes; indicated by the green, orange and blue bars respectively). The impact factor is defined as the enhancement in the probability of high pollution episodes due to extreme meteorological events. Background color indicates the mean concentration for that pollutant. Bar plots for the 4 smallest States (includes District of Columbia, Rhode Island, Delaware, and Connecticut) are omitted to increase accessibility.

In our study, we also find that the wet removal efficiency and hence the atmospheric lifetime of aerosols have significantly higher sensitivities to precipitation frequencies than to precipitation intensities, implying that an increase in the total precipitation amount does not necessarily lead to a decrease in the black carbon (BC) lifetime. This is better illustrated in Fig 5, which shows the BC lifetime as a function of the precipitation intensity and frequency. Compared with the control scenario (i.e., the original precipitation intensity and frequency, as labeled by the black star), any point in the area between the two solid curves (one shows a constant total precipitation amount and the other shows a constant BC lifetime) would have a higher total precipitation amount and a longer BC lifetime. This indicates that, even with an increased total precipitation, the BC lifetime (and hence the atmospheric concentrations of BC) can still increase if the precipitation frequency decreases significantly.

Fig. 5. Model calculated atmospheric lifetime as a function of precipitation intensity and frequency. The dashed contour lines indicate atmospheric lifetimes of black carbon (BC) aerosols. The green solid line represents the conditions with the same amount of total precipitation as the base simulation (control run). The red solid indicates conditions leading to atmospheric lifetimes of black carbon aerosols the same as the base simulation (control run).

 

Conclusions:

Using the derived sensitivities of ozone and PM to various extreme air pollution meteorological events, we have developed statistical models for calculating the probability of high ozone or PM pollution episodes based on occurrences of heat waves, temperature inversion, atmospheric stagnation episodes, and wildfires. These models are much less demanding on computing resources than the complex chemical transport models and thus offer a fast and convenient empirical tool for predicting the risk of strong air pollution events based on either short-term weather forecast or climate-induced long-term changes in meteorology.

Finally, we have examined the long-term trends in extreme air pollution meteorological events in the future decades with global 3D models. The simulations following the scenarios of RCP 4.5 and RCP 6.0 both show significant increases in the likelihood of extreme air pollution meteorological events by the 2050s, especially for heat waves. The potential impacts on ozone and PM air quality from these projected changes in extreme meteorological events were also calculated. Our results reveal significant impacts of climate change on air quality and the associated risk for public health. These impacts need to be accounted for in long-term planning of air pollution control strategies.


Journal Articles on this Report : 12 Displayed | Download in RIS Format

Other project views: All 28 publications 12 publications in selected types All 12 journal articles
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Journal Article Hickman JE, Huang Y, Wu S, Diru W, Groffman PM, Tully KL, Palm CA. Nonlinear response of nitric oxide fluxes to fertilizer inputs and the impacts of agricultural intensification on tropospheric ozone pollution in Kenya. Global Change Biology 2017;23(8):3193-3204. R835189 (Final)
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  • Journal Article Hou P, Wu S. Long-term changes in extreme air pollution meteorology and implications for air quality. Scientific Reports 2016;6:23792 (9 pp.). R835189 (2015)
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  • Journal Article Hou P, Wu S, McCarty JL, Gao Y. Sensitivity of atmospheric aerosol scavenging to precipitation intensity and frequency in the context of global climate change. Atmospheric Chemistry and Physics 2018;18(11):8173-8182. R835189 (Final)
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  • Journal Article Huang Y, Wu S, Kaplan JO. Sensitivity of global wildfire occurrences to various factors in the context of global change. Atmospheric Environment 2015;121:86-92. R835189 (2014)
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  • Journal Article Huang Y, Wu S, Kramer LJ, Helmig D, Honrath RE. Surface ozone and its precursors at Summit, Greenland: comparison between observations and model simulations. Atmospheric Chemistry & Physics 2017;17(23):14661-14674. R835189 (Final)
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  • Journal Article Kumar A, Wu S, Weise MF, Honrath R, Owen RC, Helmig D, Kramer L, Val Martin M, Li Q. Free-troposphere ozone and carbon monoxide over the North Atlantic for 2001-2011. Atmospheric Chemistry and Physics 2013;13(24):12537-12547. R835189 (2012)
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  • Journal Article Kumar A, Wu S, Huang Y, Liao H, Kaplan JO. Mercury from wildfires: global emission inventories and sensitivity to 2000–2050 global change. Atmospheric Environment 2018;173:6-15. R835189 (Final)
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  • Journal Article Thelen B, French NHF, Koziol BW, Billmire M, Owen RC, Johnson J, Ginsberg M, Loboda T, Wu SL. Modeling acute respiratory illness during the 2007 San Diego wildland fires using a coupled emissions-transport system and generalized additive modeling. Environmental Health 2013;12:94 (22 pp.). R835189 (2012)
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  • Journal Article Wai KM, Wu S, Kumar A, Liao H. Seasonal variability and long-term evolution of tropospheric composition in the tropics and Southern Hemisphere. Atmospheric Chemistry and Physics 2014;14(10):4859-4874. R835189 (2012)
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  • Journal Article Zhang B, Owen RC, Perlinger JA, Kumar A, Wu S, Val Martin M, Kramer L, Helmig D, Honrath RE. A semi-Lagrangian view of ozone production tendency in North American outflow in the summers of 2009 and 2010. Atmospheric Chemistry and Physics 2014;14(5):2267-2287. R835189 (2012)
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  • Journal Article Zhang H, Wu S, Huang Y, Wang Y. Effects of stratospheric ozone recovery on photochemistry and ozone air quality in the troposphere. Atmospheric Chemistry and Physics 2014;14(8):4079-4086. R835189 (2013)
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  • Journal Article Zhang H, Holmes CD, Wu S. Impacts of changes in climate, land use and land cover on atmospheric mercury. Atmospheric Environment 2016;141:230-244. R835189 (2015)
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  • Supplemental Keywords:

    Extreme events, air pollution meteorology, climate change, air quality, ozone, particulate matter

    Progress and Final Reports:

    Original Abstract
  • 2012 Progress Report
  • 2013 Progress Report
  • 2014 Progress Report
  • 2015 Progress Report