OZONESONDE MEASUREMENTS AT OZONE NON-ATTAINMENT AREA

1
OZONESONDE MEASUREMENTS AT OZONE NON-ATTAINMENT
AREA

• Segun Ogunjemiyo and Samuel Omolayo
• Presented at CMAS 2009, Chapel Hill, NC
• Environmental Research Laboratory, Department of
  Geography
• California State University, Fresno, CA 93740
• Email sogunjemiyo_at_csufresno.edu

2
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

3
Why care about ground level ozone?

• 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

4
Ozone accumulation at the surface

• 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-destructi
  on balance include
• local sources and sinks of ozone and ozone
  precursors
• horizontal and vertical transport

(Neu et al., 1994 Kleinman et al., 1994 Fast et
al., 2002 Lin et al., 2004 and 2006).
5
Vertical transport of ozone

• 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

6
Boundary Layer Depth and Structure
SourceStull,1990
7
Ozone profiles and boundary layer
8
General consensus

• 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

9
OZONESONDE MEASUREMENTS

• Goals
• to provide insight into the vertical transport of
  ozone
• to generate data for improving air quality
  forecast for the study region

10
Study Site North East Fresno
Clovis/N. Villa
11
Ozone Non-Attainment Areas

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

• 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 Californias population
• Two largest metropolitan area are Fresno and
  Bakersfield

12
10 Most Ozone-Polluted Cities 2007
Metropolitan Statistical Areas
1 Los Angeles-Long Beach-Riverside, CA
2 Bakersfield, CA
3 Visalia-Porterville, CA
4 Fresno-Madera, CA
5 Houston-Baytown-Huntsville, TX
6 Merced, CA
7 Dallas-Fort Worth, TX
8 Sacramento--Arden-Arcade--Truckee, CA-NV
9 Baton Rouge-Pierre Part, LA
10 New York-Newark-Bridgeport, NY-NJ-CT-PA
http//lungaction.org/reports/sota07_cities.html
13
San Joaquin Valley ozone trend
14
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
15
Exceedances of 8-hour Ozone NAAQS (0.075 ppm) in
Fresno
16
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

17
Factors that make the San Joaquin Valley
vulnerable to air pollution

• Topography
• The Sierra Nevada and Coastal ranges trap
  airborne pollutants near the Valley floor. 
• Climate
• The Valleys hot summer temperatures aid in the
  formation of harmful smog.
• Growing population
• As population levels increase, so does air
  pollution. More cars and more activities
  contribute to poor air quality.

18
The Tethersonde/Ozondesonde System
19
Tethersonde
20
Tethered ozonesonde
21
Tethered ozonesonde

• 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

Connecting the current sensor to the interface
card
22
Ozonesonde - Instrument Calibration/Conditioning
23
Electric Winch
Major Winch components
24
Balloon inflation
25
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

26
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)

27
Variables measured
28
Results 08/23/07
29
Local Time Mixing Layer Height (m) Avg Ozone in Mixing Layer (ppb) Ground Level ozone (ppb)
1000 350 48.415 44.88
1100 450 53.05174 50.91
1200 690 67.87171 69.56
1300 730 72.19892 75.25
1400 gt800 77.48235 78.22
1500 gt800 76.00413 74.22
1600 gt800 78.15511 74.57
1700 gt800 74.36625 75.01

30
Results 09/08/07
31
Results 09/08/07
Mixing Layer Height (m) Avg Ozone in Mixing Layer (ppb) Ground Level ozone (ppb)
1000 165 23 25
1100 265 35 31
1200 345 49 46
1300 425 65 61
1400 605 89 76
1700 605 90 89
32
Results 08/10/07
33
(No Transcript)
34
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

35
Acknowledgements

• Funding for this study was provided by NSF
  through the MRI Program and by the College of
  Social Sciences, California State University,
  Fresno