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Tropospheric ozone and its precursors over the United States: Sources and intercontinental influence. Rynda Hudman Postdoctoral Fellow University of California, Berkeley. Lawrence Livermore National Lab June 17, 2010. = NO x. Alt (km). - PowerPoint PPT Presentation
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Tropospheric ozone and its precursors over the United States:
Sources and intercontinental influence
Rynda Hudman Postdoctoral Fellow
University of California, Berkeley
Lawrence Livermore National Lab June 17, 2010
CONTINENT 2 OCEANCONTINENT 1
INTERCONTINENTAL INFLUENCE OF OZONE (1) primary constituent of smog in surface air [NRC, 1991]
(2) 3rd most important greenhouse gas [IPCC, 2007]
OH HO2
CO, VOCs
NONO2
h
Hemispheric Pollution
Direct Intercontinental Transport(1 week)
Air quality
Greenhouse gas
4
8
2
Alt (km)
10
6
Air quality
O3= NOx
NOx HAS OTHER WIDESPREAD CONSEQUENCES
NO
NO2 HNO3
• Acidification of soils and waterways
• Eutrophication of waterways
• Forest die-back
• impacts carbon sequestration
• Secondary organic aerosol formation
• Impacts GHG lifetimes through its effect on OH
hrs - 1 day
SOURCES OF NOx
Fossil Fuel
ANTHROPOGENIC SOURCESBIOGENIC SOURCES
FF: 21-28 TgN/yrBB: 6-12 Tg N/yr
Lightning: 1-6 TgN/yr
*Numbers from IPCC [2007]
Biomass Burning
Natural Soils: 5-8 TgN/yr
Agr: 0.5-2 TgN/yr
• Can we better constrain the magnitude of these sources?
• Can we go beyond previous work and understand the physical processes governing biogenic sources?
AgricultureNatural Soils
OUTLINE
Do we understand nitrogen transformations in the atmosphere?
Can we constrain magnitude and processes governing N sources over North America?
•Anthropogenic •Lightning•Soils•Biomass Burning
What are the impacts on hemispheric ozone and air quality?
UNITED STATES OCEANASIA
SOURCES
1. TRANSPACIFIC TRANSPORT OF ASIAN POLLUTION AND IMPACT ON U.S. AIR QUALITY
CHEMICAL EVOLUTION AIR QUALITY IMPACTS
NO
NO2 HNO3 (soluble)
PAN (insoluble, thermally unstable)
NOy
NOAA ITCT-2k2: APRIL – MAY 2002Monterey, CA
Flight path: Sampled several Asian pollution plumes
May 5th
May 17th
5-7 km
High CO
Moderate Ozone
2-4 km
High CO
High Ozone
Primarily Anthropogenic, but very different pathways
Hudman et al., [2004]
TWO FOSSIL FUEL POLLUTION PLUMES OF ASIAN ORIGIN
High PAN
PAN NOx HNO3
LARGE PAN DRIVEN OZONE PRODUCTION
Observational Estimate:
17 ppbv ozone produced from 320 pptv PAN
Ozone production per unit NOx ~ 50
~50% of ozone produced from PAN decomposition
Hudman et al., [2004]
PAN DRIVEN OZONE PRODUCTION IN SUBSIDING TROPOSPHERIC POLLUTION PLUMES
Observations: 38 ± 7 ppb (unfiltered), GEOS-Chem model: 39 ± 5 ppb 41 ± 5 ppb (filtered against local influence)
[Goldstein et al.,2004]
Model vs observations at Trinidad Head (April – May 2002)
WHY WERE NO PLUMES SEEN AT THE SURFACE?
Analogy to dust: X10 dilution as plume entrained to boundary layer 20 ppbv ozone enhancement 2 ppbv enhancement at the surface
Likely very different at mountain sites, due to greater exposure to FT!
OCEAN
2. CONSTRAINING ANTHROPOGENIC SOURCES OF NOx
GEOS-CHEM SIMULATION• Lightning, Soils
• NEI 99 FF Emiss
•Daily biomass burning inventory
ICARTT Campaign
July-August 2004
Full mapping of Eastern U.S. and North Atlantic
LARGE DISCREPENCY IN SURFACE NOx and CO Mean comparison along the flight tracks
Measurements: CO (J. Holloway), NOx (T. Ryerson)Hudman et al. [2007]
BL bias in CO and NOx
Observed Simulated Improved Simulation
DC-8 Midwest
Model / Observed NOx (0-2 km)
Hudman et al. [2007]
[ratio]
Large overestimate powerplant/industry dominated Midwest and in the South
50% reduction in power and industry source due to SIP Call [Frost et al., 2006]
ICARTT OBSERVATIONS CONFIRM LARGE DECREASE SINCE 1999 IN INDUSTRY/POWER SOURCE
Measurements (WP-3D, DC-8): T. Ryerson (NO2), Ron Cohen/Tim Bertram (NO2)
Measurments: J. Holloway, G. Sachse, A. Goldstein
BOTH AIRCRAFT AND SURFACE DATA CO EMISSIONS ARE 2.5 TIMES TOO HIGHERROR IN OTHER SPECIES
Air
craf
t (0
-1.5
km
) OBSERVED SIMULATED (NEI99) SIMULATED (anthro CO reduced by 60%)
Measurments:
J. Holloway, G. Sachse
Ch
ebo
gu
e P
oin
t (s
urf
ace)
Measurments: A. Goldstein
Hudman et al. [2008]
OZONE REDUCTIONS RESULTING FROM DECREASE IN NOx EMISSIONS
Hudman et al. [2009]Bias reduces previous model of 5- 15 ppbv
3. LIGHTNING SOURCES OF NOx
Large UT NOx bias
Ozone FT bias 5-10 ppbv
Hudman et al. [2007]NO: W. Brune, NO2: R. Cohen/T Bertram
UT NOx (8 – 12 km)
GEOS-Chem X4 DC-8
UT NOx OBSERVATIONS POINT TO A LARGER THAN EXPECTED LIGHTNING NOx SOURCE
[ppbv]
Lightning parameterization in model (flashes/km2/s):
Land: ~CTH4.9 ,
Ocean: ~CTH1.73
CTH= Cloud Top Height
Price and Rind [1992]
FLASH RATES WELL SIMULATED IN SOUTH POINTING TO A LARGER YIELD/FLASH AT NORTHERN MIDLATITUDES
GEOS-Chem
NLDN
Flash Comparison (flashes/km2/s)
0.22 0.33
OZONE COMPARISON INTEX-NA SOUTHEAST U.S. Increasing lightning yield X4 to 500 mol/flash has ~10 ppbv effect on
ozone
NO2O3
Hudman et al. [2007]…suggests great sensitivity of ozone to climate change
Observed Simulated Improved Simulation
2004 was not an anomalous lightning year
Hudman et al. [2009]
SUMMERTIME NORTH AMERICAN OZONE ENHANCEMENTS
Biomass Lightning Anthropogenic
Simulated Observed All
North American
Source
NOx
Emission (Tg N)
Hemispheric ozone
enhancement (Tg, %)
Lightning 0.28 9.1 (5.1%)
Biomass burning
0.322.0(1.1%)
Fossil fuel 0.72 10.9 (6.2 %)
All 1.32 21.9 (12.3 %)
NA Enhancement to Hemispheric Ozone
ICARTT DC-8~ Equal contributions for lightning and anthropogenic emissions in free troposphere and to NH burden
Can use to develop radiative forcing estimates
North America
Subsidence Over E Pacific
PANNOxHNO3
strong O3
X10 Dilution
Asian Plume
Asia
Europe
INFLOW
KEY RESULTS
NOx stationary sources 22%
Anthropogenic CO 60%
4
2
6
8
Alt (km)
10
O3 (ppbv)
SOURCES AND EXPORT
BB NA FF Lightning
NOx/flash4X larger than previously thought!
Export well constrained
effects on O3 & OPE
SUMMERSPRING
3. SPACE BASED CONSTRAINTS ON SOIL NOx
Most of what we know about processes responsible for soil NOx emissions is based on point measurements.
ATMOSPHERE
BIOSPHERE
NO is a low-yield product of nitrifying bacteria
N2O(g), N2(g), NO(g)
[Meixner and Yang, 2006]
Processes not well understood, HUGE spatial variability, but best correlation soil moisture (precip), T, N avail.
WHERE TO EXPECT LARGE NITRIC OXIDE EMISSIONS: Fertilized fields and monsoon regions
Pulsing : Release of soil NO following rain event, due N-buildup & reactivation of water-stressed bacteria
• Monsoon:
1. SW U.S./Mexico
2. Africa/ITCZ
3. Southeast Asia
• Fertilized Fields:
1. United States
2. Europe
LARGE SOIL NOx SOURCE INFERRED FROM SATELLITES
Regional Distribution of soil NOx
[Jaeglé et al., PNAS, 2005]
GLOBAL: 8.9 Tg N/yrMIDLATITUDES: 3.9 Tg N/yr
We examine interannual variability in soil NO emissions and our understanding of pulsing behavior over the Agricultural Great Plains
OMI NO2 Column Aug 4, 2004
• 2600 km swath width providing daily global coverage
•1:45 pm equatorial overpass time
•14 x 24 km pixel size at nadir
OZONE MONITORING INSTRUMENT (OMI) HAS MUCH FINER SCALE RESOLUTION AND DAILY GLOBAL COVERAGE
[Bertram et al., GRL, 2005]
SOIL NOx “EVENTS” pulsing over freshly fertilized Montana fields after rain event
[Bertram et al., GRL, 2005]
We extend this work to include U.S.:daily NARR Temp & Precip MODIS LandtypeFertilizer emissions [Ramankutty]
ENOx 2005-2008
Hudman et al. [2010]
CAN SOIL NOx EMISSIONS BE ROUTINELY VIEWED FROM SPACE?
MODELED SOIL NOx EMISSIONS Dry, warm conditions anomalously high modeled June 2006 soil emissions
Hudman et al. [2010]
SOIL EMISSION CONTRIBUTION TO NO2 COLUMN
June 2006
SOIL COLUMN / TOTAL COLUMN SOIL S.D. / COLUMN S.D.
SOIL COLUMN = TOTAL COLUMN – NO SOIL COLUMN
GEOS-Chem global CTM (2x2.5)
Hudman et al. [2010]
We should be able to see anomalies in soil NOx and day-to-day variability over Great Plains
OMI NO2 JUNE INTERANNUAL VARIABILITY FOLLOWS PREDICTED SOIL NOx
OMI June 2006 AnomalySoil NO model June 2006
June 2006 had lower than average lightning emissions, suggesting this was not a factor here
Hudman et al. [2010]
OMI NO2 JUNE INTERANNUAL VARIABILITY FOLLOWS SOIL NOx
2005 20072006
Hudman et al. [2010]
Suggests fertilizer induced emissions of soil NOx governs monthly variability in NO2 column over Great Plains… what about pulsing?
PULSING OVER EASTERN SOUTH DAKOTA
Pulsing event reaches 4x1015 molec cm2,
~ 2 ppbv assuming 1km well mixed BL
Hudman et al. [2010]
We can use OMI to test understanding pulsing triggers
North America Asia
Europe
KEY RESULTS
• Space-based observations can offer constraints on soil NOx
•Large scale behavior consistent with models.
•Observed interannual anomaly is similar to model predictions.
•Mechanistic details of pulses bear some resemblance, learning about the process of soil NOx emissions remains a challenge.
•Because large scale features are well represented ozone air quality
MEAN MAXIMUM 8-HR OZONE ENHANCEMENT DUE TO SOIL NOx
Ozone enhancement due to soil NOx emission doubles from 3 6ppbv, with events up to 16 ppbv!
Comparable to decreases from power plant legislation discussed earlier.
Hudman et al. [2010]
Hudman et al. , in prep.
4. BIOMASS BURNING & CLIMATE
North America
•What is the relationship between Area Burned and Meteorology/Moisture?
• We can drive these relationships into the future using GCM Future Area Burned
• Develop future ozone and aerosol precursor emission estimates
•Chemical transport model (driven by GCM winds) impacts on air quality
During ICARTT, we were able to put some estimates on NOx
emissions from fires…here we want to look at processes….
CANADIAN FIRE WEATHER INDEX MODEL
2/3 day 15 day 52 dayDrying time
Severity Rating
WEATHER
MOISTURE
FIRE DANGER
Jul 1 – Aug 15 2004 Anomaly
Strong Alaskan Ridge record fires
+60
500hPa GEOPOTENTIAL HEIGHT
Height of pressure level above mean sea level
Strong ridges are accompanied by warm and dry weather conditions at the sfc
(Hudman et al., in prep)
Regressions capture 74% of the variability in Canada and Alaska
Major predictors: 500 mb GPH (large scale stagnation) and drought indices
Hudman et al. , in prep.
REGRESSIONS CAPTURE VARIABILITY OF AREA BURNED
34% increase over Alaska, 8% (-34 to +118%) increase in Canada. Large regional variability.
2000-2050 change in area burned
RAIN VS. STAGNATION UNCERTAINTY IN RESPONSE
++ Rain500 GPH changes
Hudman et al., in prep
(Hudman et al., in prep)
CHANGE IN SURFACE OZONE ENHANCMENT JUL-AUG
Doubling of enhancement over Alaska, 1-2ppbv increase over populated Quebec cities and Midwest (20-40% increase)
A decrease of ozone toward the Arctic
PERCENT CHANGE IN SURFACE OC/EC JUL-AUG Preliminary Result
(Hudman et al., in prep)
[%]
Transport of Black Carbon aerosol to the Arctic decreases by 40%
KEY RESULTS
500 mb GPH anomaly & fuel moisture are most important variables
Large regional variability in the response, due to dependence on rainfall vs. stagnation (highly GCM dependent).
Present day ozone enhancements due to wildfire 3-10 ppbv over Canada and Alaska. Future fire increases range from -2 - +4 ppbv. Large decreases of BC toward the Arctic.
North America
WHAT HAVE WE LEARNED? FUTURE DIRECTIONS?
1. TRANSFORMATION: PAN decomposition represents a major and possibly dominant component of the ozone enhancement in transpacific Asian pollution plumes. Dilution limits surface impacts.
2. ANTHROPOGENIC: NOx reduction legislation has been successful 4-8 ppbv decrease in summertime ozone.
3. CO emissions are overestimated in current inventories impacts on other species estimates such as CO2
4. LIGHTNING: Lightning at midlatitudes produces X4 more NOx/flash than midlatitude/subtropical storms 10-15 ppbv ozone, comparable to anthropogenic emissions
5. SOIL: Soil NOx emissions are highly dependent on temperature and precipitation, impacts on ozone ~6 ppbv (events reaching 16 ppbv), comparable to #2 above.
6. BIOMASS BURNING: Future fire activity likely depends on fuel moisture and atmospheric stability, both of which are highly variable in GCM projections.
ACKNOWLEDGEMENTS
Thanks for your attention!
Advisors: Ron Cohen, Daniel Jacob, Jennifer Logan, Loretta Mickley, Students and postdocs: Lee Murray, Dominick Spracklen, Ashley Russell, Luke Valin, Solene Turquety, Shiliang Wu, Dylan Millet, Agency: Mike Flannigan (CFS), Alan Cantin (CFS), Alice Gilliland (EPA)
FUNDING: EPA, NASA, NOAA, NSF PhD Fellowship, AMS Graduate Fellowship
ITCT-2K2 & ICARTT, Science TeamsAURA Science Team