Ozone in the Central Valley of California

Transcription

1 Ozone in the Central Valley of California Thomas A. Cahill, Professor, Atmospheric Sciences and Physics, and Head, DELTA Group University of California, Davis Presentation at the Symposium, Unique Valley; Unique Solutions San Joaquin Valley AQMD, Sept. 29, 2004

2 Statement of the Problem:

3 Statement of the Problem: Ozone in the Central Valley frequently violates state and federal 1 hr (0.12 ppm) and 8 hr (0.085 ppm) standards

4 Statement of the Problem: Ozone in the Central Valley frequently violates state and federal 1 hr (0.12 ppm) and 8 hr (0.085 ppm) standards But.

5 Statement of the Problem: Ozone in the Central Valley frequently violates state and federal 1 hr (0.12 ppm) and 8 hr (0.085 ppm) standards But. Ozone peak values do not vary strongly from rural Shasta County to impacted Kern County

6 Statement of the Problem: Ozone in the Central Valley frequently violates state and federal 1 hr (0.12 ppm) and 8 hr (0.085 ppm) standards But. Ozone peak values do not vary strongly from rural Shasta County to impacted Kern County Most ozone precursors in the Central Valley (and upwind Bay Area) have decreased sharply in the past decade, but

7 Statement of the Problem: Ozone in the Central Valley frequently violates state and federal 1 hr (0.12 ppm) and 8 hr (0.085 ppm) standards But. Ozone peak values do not vary strongly from rural Shasta County to impacted Kern County Most ozone precursors in the Central Valley (and upwind Bay Area) have decreased sharply in the past decade, but Ozone peak values in the Central Valley have changed little in the same period.

8 Statement of the Problem: Ozone in the Central Valley frequently violates state and federal 1 hr (0.12 ppm) and 8 hr (0.085 ppm) standards But. Ozone peak values do not vary strongly from rural Shasta County to impacted Kern County Most ozone precursors in the Central Valley (and upwind Bay Area) have decreased sharply in the past decade, but Ozone peak values in the Central Valley have changed little in the same period. Conclusion: We are deficient in our knowledge of sources and mechanisms for ozone formation in the Central Valley of California

9 Ozone Trends in Fresno

10 NOx Emissions by County Fresno Kern Santa Clara Contra Costa Sacramento Tons/day Year

11 Hypotheses to Explain Fresno Ozone Values 1. The ppm global ozone background is enhanced by Central Valley conditions 2. There are additional ground level local and transported sources of ozone and its precursors, and 3. There is high altitude transport to Fresno of ozone and its precursors from upwind sources

12 Ozone Trends in the Central Valley 8 hr Average - Average 4th highest day Yreka Redding Red Bluff Chico Sacr Fresno Visalia Bakersfield CA standard ppm Valley natural background? EPA standard 0.02 Est. Global ozone

13 Redding

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15 Topic 1. Background Ozone There are many millions of people upwind of Fresno, few upwind of Redding There are significant natural sources of ROGs (isoprene) from oak trees enhanced by agriculture, There are natural and agricultural area wide sources of NO x from soil outgassing, Extreme valley temperatures enhance these emission processes and conversion to ozone. Propose: Valley ozone background ~ 0.07 ppm

16 Topic 2. Local Ozone Most ozone precursors in the Valley and Bay Area have decreased, 1980 present Ozone peaks at Fresno and the San Joaquin Valley did not track that reduction Other major areas in California did track those historical reductions Recently, stationary sources of ROGs and NO x, local and Bay Area, have stabilized and even risen slightly

17 Yield - a proposed metric for how well we are doing

18 Yield - a proposed metric for how well we are doing Linear roll back assumes proportional improvement between the sources and ambient concentrations Yield = % reduction pollutant/ % reduction source x 100 % For linear roll back, the assumed yield is 100%. In the San Joaquin Valley, the yield approaches.. Zero! 0%! Null! Nada! Lame! Bummer

19 Ozone decline vs. precursor decline, circa Yield in ozone reduction vs. precursor reduction

20 Ozone decline vs. precursor decline, circa Yield in ozone reduction vs. precursor reduction Los Angeles 1 hr ozone Los Angeles % 8 hr ozone Los Angeles % 82% yield ROG % 51% (averaging NOx % over ROG Bay Area and NOx) 1 hr ozone Alameda % 8 hr ozone Alameda % 52% yield NOx % 43% ROG % San Joaquin Valley 1 hr ozone Fresno % 8 hr ozone Fresno % 5% yield ROG % 44% NOx %

21 Ozone decline vs. precursor decline, circa (with ppm background removed from 8 hr values) Los Angeles 1 hr ozone Los Angeles % 8 hr ozone Los Angeles % ROG 0.45 vs. 51% 108% NOx 0.52 Bay Area 1 hr ozone Alameda % 8 hr ozone Alameda % 98% NOx 0.63 vs. 44% ROG 0.50 San Joaquin Valley 1 hr ozone Fresno % 8 hr ozone Fresno % 9% ROG 0.45 vs. 44% NOx 0.67

22 Ozone (max hr) and Temperature at the Fresno 1st Street Super-site T max scaled = (Tmax F - 40)/500) Ozone peak hour Temp max (scaled) T max = 108 F) 0.1 ppm Month, 2002

23 Ozone (max hr) and Temperature at the Fresno 1st Street Super-site T max scaled = (Tmax F - 40)/500) Ozone peak hour Temp max (scaled) T max = 108 F) ppm Redding avg Month, 2002

24 Ozone (max hr) and Temperature at the Fresno 1st Street Super-site T max scaled = (Tmax F - 40)/500) Ozone peak hour Temp max (scaled) T max = 108 F) ppm Redding avg Month, 2002

25 Ozone (max hr) and Temperature at the Fresno 1st Street Super-site T max scaled = (Tmax F - 40)/500) Ozone peak hour Temp max (scaled) T max = 108 F) ppm Redding avg Month, 2002

26 0.2 Hourly ozone - July 10, 2002 High temperature, 108 F Gaseous pollutants at the Fresno 1st Street Super-Site Hourly Averages - worst ozone day of the year, Prior EPA 1 hr standard Ozone ppm 0.1 New EPA 8 hr standard 0.05 NO x 5 CO/10 NO2 x Hour

27 Topic 3. Transported Ozone Industrial plumes well known in work in the western US and elsewhere These plumes do not follow normal ground level chemistry due to their composition (often lack ROGs, ammonia, ) There are a major sources of ozone precursors in and near the Carquinez Strait, esp. NO x at circa 55 tons/day These sources use tall stacks to loft plumes to higher elevations They have not decreased much if at all in the past decade

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29 Nitric oxide and ozone (scaled), Fresno, 2002 Nitric Oxide and Ozone at Fresno, Summer, 2002 Nitric Oxide Ozone ppm Parts per million June July

30 Support for Carquinez Transport Very high ozone (circa 0.35 ppm) and precursor layers perched above the Sierra Nevada Carroll et al, UC Davis, 1990s National Park Service power plant studies, 1987 ff Refinery aerosol into the Lake Tahoe basin, summer and winter Cahill et al, USFS Watershed, 2000 Refinery aerosols at night on downslope winds, Yosemite NP Cahill et al, NPS Yosemite 2002

31 Summary of Ozone Extreme Days at Fresno The air mass came over the Bay Area at elevation circa 2000 m, and rose to elevated levels in the Sierra Nevada The air descended at night with NO and ROG (including prior day s tree emissions, too?) and via compressional heating and sunlight, reached extreme temperatures next day at Fresno. The air spent hardily any time on the valley floor

32 Ozone impact on the Sierra Nevada forests Extensive analysis of the impact of ozone on Ponderosa and Jeffery pines was included in two articles in the Sierra Nevada Ecosystem Project (SNEP) reports of the USDA 1997 A value of roughly 0.09 ppm was found to be the threshold for damage This level is routinely violated at Sequoia and Yosemite NP but rarely in the northern Sacramento Valley

33 Valley ozone transport into the Sierra Ozone Transect - Visalia to Sequoia NP July 3, 2002 (90th quartile-summer) Visalia Lower Kaweah Ash Mountain Lookout Point EPA 8 hr standard 0.08 ppm Time of Day

34 Hypotheses to Explain Fresno Ozone Values 1. The ppm global ozone background is enhanced by Central Valley conditions and area sources to ~ 0.06 to 0.07 ppm 2. There are standard ground level local and transported sources of ozone and its precursors, ~ 0.02 to 0.03 ppm 3. There is high altitude transport of NO to Fresno from Bay Area refineries and power plants, ~ 0.04 ppm

35 Needed Research Analysis of why ozone is so high Davis to Redding Role of natural sources, agricultural enhancement Direct aircraft plume tracing, Bay Area tall stack sources to Fresno Periodically, these plumes are seen by accident (Jim Pitts, Moss landing 1970s )

36 BAAQMD Actions, ARB Demands

37 BAAQMD Actions, ARB Demands This result is in accord with the California ARB Report Assessment of the Impacts of Transported Pollutants on Ozone Concentrations in California, March, 2001, finding overwhelming pollutant transport from the San Francisco Bay Area to the San Joaquin Valley and that (b) 1. require the adoption and implementation of best available retrofit and control technology, as defined in the Health and Safety Code section (pg. E-5). Bay Area AQMD mitigation efforts 1992 to Are these efforts enough?

38 Bakersfield Golden State Highway Kern County

39 Mystery site #1

40 Mystery Site #2

41 Mystery site #3

42 Mystery Site #4

43 Bakersfield Golden State Highway Kern County

44 How Did you Do? Mystery Site #1: Redding Mystery Site #2: Sacramento Mystery Site #3: Folsom Mystery Site #4: Placerville Conclusion: Big east-west gradient; small north south gradient high natural background