Impact of Climate Change on Air Quality for Three Midwestern USA Cities Abhishek,* Joo-Youp Lee,** and Tim C. Keener* *Department of Civil & Environmental Engineering **Department of Chemical & Materials Engineering University of Cincinnati Cincinnati, Ohio 45221   Y. Jeffery Yang National Risk Management Research Laboratory U. S. Environmental Protection Agency MS 690, 26 W. Martin Luther King Drive, Cincinnati, Ohio 45268, U.S.A.

PRESENTATION OUTLINE Climate Change Data Mining and Analysis Results Need for Wind Speed Study Data Mining and Analysis Results Ozone Season Analysis Possible Causes Implications

Climate Change Factors Important for Air Quality Temperature The frequency and pattern of cloud cover Circulation and precipitation patterns

Importance of Wind Speed Study Ventilates the pollutants Transfers heat and moisture between the earth’s surface and the atmosphere Affects engineering design Used for energy generation Affects human comfort Affects ozone formation

2. DATA MINING AND ANALYSIS

Data Mining and Analysis Data was obtained from the National Oceanic and Atmospheric Administration (NOAA) website. Three Midwest USA Cities selected were: Cincinnati (Ohio), Indianapolis(Indiana) and Little Rock (Arkansas). The data was available from 1943-2008 for Indianapolis and Little Rock and from 1948-2008 for Cincinnati. All wind data was in the form of hourly recordings of wind speeds (in m/s).

Latitude and Longitudes City Latitude Longitude Cincinnati 39° 9' N 84° 31' W Indianapolis 39° 44' N 86° 17' W Little Rock 34° 44' N 92° 14' W

Why these cities? Because their topography is relatively flat and unaffected by large mountain ranges or other major topographical features, They represent important regional economic centers in the Midwest, Undergone major air quality management efforts over the past 35 years in order to meet the National Ambient Air Quality Standards.

Data Mining and Analysis Annual calms for all three cities were counted. Calms were defined as when wind speed is zero Hourly readings when the wind speed is zero is divided by the total number of hourly data of the year giving the calms frequency for that year, Similarly the frequency of wind speeds for the following bins were calculated: >0 – 2.1 m/s; >2.1 – 4.1 m/s; >4.1 – 6.2 m/s; >6.2 – 8.2 m/s; and, >8.2 m/s.

3. RESULTS

Results Most striking results is that calms have increased significantly in frequency for all three cities. For the combined 3-city average, calms have increased from ~3 % in the mid-1940s to a value of ~10% in 2008, an increase of over 600 hours on a yearly basis.

Results Calms Frequency: Little Rock>Cincinnati>Indianapolis Little Rock now averages around 15% of the year with calm conditions as compared to ~10 % for Cincinnati and ~6% for Indianapolis.

OZONE SEASON ANALYSIS

Climate Change and Ozone Conditions conducive to ozone (O3) formation and accumulation are abundant sunshine, high temperatures, stagnant air. Summertime pollutant in the United States. It is now well understood that year-to-year variability in summer climate is strongly correlated with the number of days that exceed O3 air quality standards.

Climate Change effect on Ozone Precursors => Higher Temperatures => increases in biogenic emissions of VOCs => High Ozone!! => warmer and wetter climate => increase in the rate of natural production of NOx by lightning => High Ozone

Results: Ozone Season Analysis For all three cities, increase in ozone season calms is more than the annual increase in calms for the entire period.

Ozone Season Vs Annual Calms City Annual slope (1) Ozone season slope (2) Years of data (3) Annual calms Increase % (1)*(3) Ozone season calms increase % (2)*(3) Cincinnati 0.1249 0.1609 61 7.6189 9.8149 Indianapolis 0.0606 0.0755 66 3.996 4.983 Little Rock 0.2368 0.2692 15.6288 17.7672

4. POSSIBLE CAUSES

Possible Causes Wind speed is related to the surface pressure gradient, which in turn is a function of the temperature gradient. The enhanced warming at higher latitudes compared to the tropics => decreased pressure gradient over the United States => reduced wind speeds. Another way that temperature changes may affect surface winds is by altering the near-surface vertical temperature gradient and thus the turbulent mixing.

Possible Causes The IPCC has reported that observations of extratropical storm track movement poleward over the last few decades have implications for the increased frequency and duration of synoptic stagnation events. A number of recent modeling studies suggest that this trend could continue into the future, resulting in significant changes in winds, precipitation, and temperature patterns in mid-latitudes.

Possible Causes Major cyclic global weather indices can be used to track these global changes which affect temperature, precipitation and surface wind trends in the United States. These include the North Atlantic Oscillation (NAO), the Pacific/ North American pattern (PNA), the Southern Oscillation Index (SOI), and the Pacific Decadal Oscillation (PDO).

IMPLICATIONS

Implications Reductions in wind speed would ventilate pollutants from urban areas less effectively (leading to increased exposure to pollutants and thereby exacerbating lung and heart diseases in the area).

Implications Fewer days with high wind speeds => problem for wind energy generation because wind power varies as the cube of the speed. Increased stagnant conditions => Increased human discomfort during summertime => increased time spent indoors => increased energy demand => more emissions!!

Implications Reduced wind can have implications on transport of pollen and mold in the area. The efficiency of heat and moisture transfers between the earth’s surface and the atmosphere is reduced if days with lower wind speed are increasing Impact on Ozone Formation.

Implications Climate modeling studies indicate potential increases in the O3 events in the Midwest and Northeast that can be directly traced to the weaker frontal systems and decreased frequency of surface cyclone activity due to a poleward storm track shift.

Consistent Findings Klink (1999) looked at the 1961–90 trends at several U.S monitoring stations and found that mean monthly minimum wind speed are decreasing. Klink (2002) analyzed seven stations in Minnesota and the Dakotas. Record lengths varied from 22 to 35 years. Most of the seven stations showed a trend toward reduced mean annual wind speeds. Keimig and Bradley (2002) analyzed 15 Canadian and Alaskan stations. 64% of the monthly trends in wind speed were negative (decreasing wind speed). Gower (2002) investigated the trends and variations in 6 to 27 years of wind speed data from buoys off the west coast of Canada and the USA and observed decreasing wind speeds.

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