OZONESONDE MEASUREMENTS AT OZONE NON-ATTAINMENT AREA

Segun Ogunjemiyo* and Samuel OmolayoPresented at CMAS 2009, Chapel Hill, NC

*Environmental Research Laboratory, Department of Geography

California State University, Fresno, CA 93740

Email: sogunjemiyo@csufresno.edu

Ozone A triatomic oxygen molecule (O3)

occurs naturally in the stratosphere, where it absorbs and shield the surface from elevated UV radiation

a product of chemical oxidations in the troposphere , where it is a major component of photochemical smog

Causes physical injuries and physiological effects in plants Has been linked to various health problems

Ozone can trigger asthma attacks, which occur when the airways of the lungs become inflamed and swollen

Why care about ground level ozone?

Level is determined by the balance between the rate of photochemical production and destruction of ozone by dry deposition and titration of NOx, NO2, and other gases from surface emissions

The production is enhanced by conditions such stagnant air intense solar radiation high temperature absence of rainfall

Other factors influencing the production-destruction balance include local sources and sinks of ozone and ozone precursors horizontal and vertical transport

Ozone accumulation at the surface

(Neu et al., 1994; Kleinman et al., 1994; Fast et al., 2002; Lin et al., 2004 and 2006).

The significance of downward mixing of ozone-rich air aloft to ground level ozone accumulation has been noted (e.g. McKendry et al., 1997; Zhang and Rao, 1999; Vokovich and Scarborough, 2005; Kim et al., 2007; Lin 2008)

A relationship has also been observed between ozone peak concentration at 1-2 km layer to the next day maximum ground level ozone concentration

Vertical transport of ozone

Boundary Layer Depth and Structure

Source:Stull,1990

Ozone profiles and boundary layer

The entrainment of ozone in the boundary layer needs further investigation to

better improve our current knowledge of vertical ozone transport improve existing ozone forecasting models

General consensus

OZONESONDE MEASUREMENTS

Goalsto provide insight into the vertical transport of

ozone to generate data for improving air quality

forecast for the study region

Study Site: North East FresnoClovis/N. Villa

Ozone Non-Attainment Areas

Includes the San Joaquin Valley of CA, which stretches across eight counties(San Joaquin, Stanislaus, Merced, Madera, Fresno, Kings, Tulare, and Kern)

Boarders by two mountains

10% of California’s population Two largest metropolitan area are Fresno

and Bakersfield

Areas exceeding the 2008 8-hour ozone standard (0.075 ppm)

10 Most Ozone-Polluted Cities 2007

Metropolitan Statistical Areas

1 Los Angeles-Long Beach-Riverside, CA2 Bakersfield, CA3 Visalia-Porterville, CA4 Fresno-Madera, CA5 Houston-Baytown-Huntsville, TX6 Merced, CA7 Dallas-Fort Worth, TX8 Sacramento--Arden-Arcade--Truckee, CA-NV9 Baton Rouge-Pierre Part, LA10 New York-Newark-Bridgeport, NY-NJ-CT-PA

http://lungaction.org/reports/sota07_cities.html

San Joaquin Valley ozone trend

Fresno smog

Fresno Pacific Towers -- the former Security Bank building -- looms through smog in downtown Fresno. Source: Fresno bee

Clear sky tops a layer of smog over Fresno, Calif., in this August 2002 photo. A proposed rule would require builders to reduce air pollution. Source: Fresno Bee

Exceedances of 8-hour Ozone NAAQS (0.075 ppm) in Fresno

Where does the SJV pollution come from?

A significant portion of the total air pollution is from the Bay Area

• 27% in the northern portion

• 11% in the central • 9 % in the southern valley

Source: SJVAPCD.COM

Factors that make the San Joaquin Valley vulnerable to air pollution

TopographyThe Sierra Nevada and Coastal ranges trap airborne pollutants near the Valley floor. 

ClimateThe Valley’s hot summer temperatures aid in the formation of harmful smog.

Growing populationAs population levels increase, so does air pollution. More cars and more activities contribute to poor air quality.

The Tethersonde/Ozondesonde System

Tethersonde

Tethered ozonesonde

Tethered ozonesonde

Connecting the current sensor to the interface card

Cathode cell contains 3ml of dilute KI solution

Anode cell contains1.5 ml of a saturated KI solution.

The piston pump bubbles ambient air into the cathode cell solution, causing ozone in the air to oxidize the iodide to iodine

Electrical current generated is proportional to the amount of ozone in the air

The current is converted by the electronic interface into a digital signal compactable with the tethersonde data format

Ozonesonde - Instrument Calibration/Conditioning

Electric Winch

Major Winch components

Balloon inflation

Flight Summary 9 Flight days

Jul: 07/24, 07/30, 07/31 Aug: 08/10, 08/23 Sep: 09/04, 09/06, 09/08, 09/13

The number of flights varies between the days, ranging from 3 on 07/24 to 8 on 08/23 Approval from local control tower Prevailing weather condition (cloudy, windy conditions) Instrument malfunctions

Variables measured Air temperature (oC) Relative humidity (%) Potential temperature (oC) Dew point (oC) Specific humidity Ozone concentration (ppbv) Water mixing ratio (gm/Kg) Wind speed (m/s) Wind direction (degree) Pressure (mb) Height (m)

Variables measured

Results: 08/23/07

Local TimeMixing Layer Height (m)

Avg Ozone in Mixing Layer (ppb)

Ground Level ozone (ppb)

1000 350 48.415 44.881100 450 53.05174 50.911200 690 67.87171 69.561300 730 72.19892 75.251400 >800 77.48235 78.221500 >800 76.00413 74.221600 >800 78.15511 74.571700 >800 74.36625 75.01

Results: 09/08/07

Results: 09/08/07

Mixing Layer Height (m)

Avg Ozone in Mixing Layer (ppb)

Ground Level ozone (ppb)

1000 165 23 251100 265 35 311200 345 49 461300 425 65 611400 605 89 761700 605 90 89

Results: 08/10/07

Temperature profile: 08/10/07

0

100

200

300

400

500

600

700

800

900

15 17 19 21 23 25 27 29 31 33 35

Temperature (oC)

Heig

ht

(m) 0950

1038

1142

1235

1350

1630

Ozone profile : 08/10/07

0

100

200

300

400

500

600

700

800

900

30 40 50 60 70 80 90

Ozone (ppb)

Heig

ht

(m) 0950

1038

1142

1235

1350

1630

Final Remarks Our data highlights the roles of the boundary layer

evolution in the vertical transport of ozone More investigations are needed to fully address the the

impacts of downward mixing on surface ozone accumulation

Acknowledgements Funding for this study was provided by NSF through the

MRI Program and by the College of Social Sciences, California State University, Fresno