intercontinental transport of pollution: policy implications daniel j. jacob no x emissions (2000)...
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INTERCONTINENTAL TRANSPORT OF POLLUTION:INTERCONTINENTAL TRANSPORT OF POLLUTION:POLICY IMPLICATIONSPOLICY IMPLICATIONS
Daniel J. Jacob
NOx emissions (2000)
with Rynda Hudman, Colette Heald, Duncan Fairlie, Rokjin Park, Solene Turquety,
Arlene Fiore (now at GFDL), Qinbin Li (now at JPL)
and support from EPRI, EPA, NOAA, NASA
OZONE AND PARTICULATE MATTER (PM): OZONE AND PARTICULATE MATTER (PM): TOP TWO AIR POLLUTANTS IN THE U.S. TOP TWO AIR POLLUTANTS IN THE U.S.
# millions of people living in areas exceeding national ambient air quality standards (NAAQS) [EPA, 2002]
124 ppbv (1-hour)
84 ppbv (8-hour)
Carbon monoxide (CO)Lead
Nitrogen dioxide
Ozone (O3)
Particles < 10 m (PM10)
Particles < 2.5 m (PM2.5)
Sulfur dioxide(SO2)
Any pollutant
50 g m-3 (annual)
0 50 100 150
15 g m-3 (annual)
millions
MECHANISMS FOR INTERCONTINENTAL TRANSPORT MECHANISMS FOR INTERCONTINENTAL TRANSPORT BETWEEN NORTHERN MIDLATITUDE CONTINENTSBETWEEN NORTHERN MIDLATITUDE CONTINENTS
Asia N. America Europe
Boundary layer
Free troposphere
lifting subsidence
boundary layer advection
Tropopause
HEMISPHERIC POLLUTION BACKGROUND
“Direct”intercontinental
transport
Mixing
• Direct intercontinental transport: fast (~1 week) transport from source to receptor continent; either by boundary layer advection or by lifting to lower free troposphere followed by subsidence
• Hemispheric pollution: pollution mixes in free troposphere, affecting free tropospheric background, in turn affecting surface concentrations by subsidence
2 km
ENVIRONMENTAL IMPACTS OF ATMOSPHERIC OZONEENVIRONMENTAL IMPACTS OF ATMOSPHERIC OZONE
NOx = NO + NO2: nitrogen oxide radicalsVOC (volatile organic compounds) = light hydrocarbons and substituted organic compounds
UV shield
Greenhousegas
Primary sourceof OH radicals
Smog
GLOBAL BUDGET OF TROPOSPHERIC OZONEGLOBAL BUDGET OF TROPOSPHERIC OZONE
O3
O2 h
O3
OH HO2
h, H2O
Deposition
NO
H2O2
CO, VOC
NO2
h
STRATOSPHERE
TROPOSPHERE
8-18 km
Chem prod in troposphere
4300
1600
Chem loss in troposphere
4000
1700
Transport from stratosphere
400
400
Deposition 700
300
Tg O3 yr-1 present natural
NOx, CO, methane, nonmethane VOC (NMVOC) emissions
Ozone lifetime: ~ days in boundary layer~1 mo in free troposphere
Inventory (Tg):360 230
Limiting ozone precursors: Global - NOx and methaneRegional – NOx and NMVOCs
Mickley et al. [1999]
O3
TROPOSPHERIC OZONE BACKGROUNDTROPOSPHERIC OZONE BACKGROUND
stratosphere
Latitude over NW PacificLongitude
Chinacoast
Californiacoast
Airborne lidar observations from TRACE-P aircraft mission over N. Pacific in spring 2001 [Browell et al., 2003]
20-70 ppbv ozone background, increases with altitude and latitude
OZONE BACKGROUND IS AN IMPORTANT INCREMENT OZONE BACKGROUND IS AN IMPORTANT INCREMENT TOWARD EXCEEDANCE OF AIR QUALITY STANDARDS (AQS)TOWARD EXCEEDANCE OF AIR QUALITY STANDARDS (AQS)
0 20 40 60 80 100 120 ppbv
Europe AQS seasonal 8-h avg
U.S. AQS8-h avg.
U.S. AQS1-h avg.
Surface background at northern
midlatitudes
Japan AQS 8-h avg.
preindustrial present
OZONE BACKGROUND AT NORTHERN MID-LATITUDES OZONE BACKGROUND AT NORTHERN MID-LATITUDES HAS A LARGE ANTHROPOGENIC COMPONENTHAS A LARGE ANTHROPOGENIC COMPONENT
Observations at mountain sites in Europe [Marenco et al., 1994]
Preindustrialmodel ranges
Model overestimates of 19th century observations could reflect model errors in natural ozone sources (lightning, stratosphere)…or calibration errors in the data
GEOS-CHEMGEOS-CHEM GLOBAL 3-D MODEL GLOBAL 3-D MODELOF ATMOSPHERIC TRANSPORT AND CHEMISTRYOF ATMOSPHERIC TRANSPORT AND CHEMISTRY
• Developed by Harvard Atmospheric Chemistry Modeling Group, used by 17 research groups in N. America and Europe; ~100 publications.
http://www-as.harvard.edu/chemistry/trop/geos
• driven by GEOS assimilated meteorological observations from NASA Global Modeling and Assimilation Office (GMAO); native resolution 1ox1o
• applied to simulations of ozone, aerosols (PM), CO2, methane, mercury, hydrogen,…
• nested with EPA CMAQ regional model for studies of intercontinental transport
Results presented today are from coupled ozone-aerosol simulation with 2ox2.5o resolution, 48 vertical levels
MEAN SURFACE OZONE ENHANCEMENTS FROM ANTHROPOGENIC MEAN SURFACE OZONE ENHANCEMENTS FROM ANTHROPOGENIC
NONOxx AND NMVOC EMISSIONS IN DIFFERENT CONTINENTS AND NMVOC EMISSIONS IN DIFFERENT CONTINENTS
GEOS-CHEMmodel, July 1997
North America
Europe
Asia
Li et al. [2002]
as determined from sensitivity simulations with these sources shut off
2-6 ppbvmeanenhancementsover U.S.
Fiore et al. [2002];Li et al. [2002]
tropical air
Subsidence of Asian pollution+ local production
stagnation
RANGE OF RANGE OF INTERCONTINENTAL INTERCONTINENTAL OZONE POLLUTION OZONE POLLUTION
ENHANCEMENTSENHANCEMENTSAT SURFACE SITES AT SURFACE SITES (GEOS-CHEM model)(GEOS-CHEM model)
over U.S.
over Europe
effect is maximum for ozone concentrations in mid-range (40-70 ppbv)
EFFECT OF NORTH AMERICAN SOURCESEFFECT OF NORTH AMERICAN SOURCESON EXCEEDANCES OF EUROPEAN AIR QUALITY ON EXCEEDANCES OF EUROPEAN AIR QUALITY
STANDARD (55 ppbv, 8-h average)STANDARD (55 ppbv, 8-h average)GEOS-CHEM modelresults, summer 1997
Number of exceedance days(out of 92)
# of exceedance days thatwould not have beenin absence of N.American emissions
Li et al. [2002]
NOAA/ITCT-2K2 AIRCRAFT CAMPAIGN IN APRIL-MAY 2002 NOAA/ITCT-2K2 AIRCRAFT CAMPAIGN IN APRIL-MAY 2002 Monterey, CAMonterey, CA
High-ozone Asian pollution plumes observed in lower free troposphere but not at surface (Trinidad Head);strong stratospheric influence (Trinidad Head sondes)
CO
O3
PAN
HNO3
May 5 plume at 6 km:High CO and PAN,no O3 enhancement
May 17 subsidingplume at 2.5 km:High CO and O3,PAN NOxHNO3
Hudman et al. [2004]
Observations by D. Parrish, J. Roberts, T. Ryesrson (NOAA/AL)
CONCEPTUAL PICTURE OF OZONE PRODUCTIONCONCEPTUAL PICTURE OF OZONE PRODUCTIONIN TRANSPACIFIC ASIAN POLLUTION PLUMESIN TRANSPACIFIC ASIAN POLLUTION PLUMES
NOx
HNO3
PANAsianboundarylayer(OPE ~ 5)
PAN, weak O3
Warm conveyor belt; 5-10% export of NOy mainly as PAN
strong O3
Subsidence Over E Pacific
OPE 60-80PAN NOxHNO3
U.S.boundarylayer very weak O3
10x dilution(Asian dust data)
E. Asia Pacific United States
Hudman et al. [2004]
Stratosphericdownwelling
GEOS-CHEM ozone production efficiency (2-4 km)
SURFACE OZONE AT TRINIDAD HEAD, CALIFORNIA SURFACE OZONE AT TRINIDAD HEAD, CALIFORNIA DURING ITCT-2K2DURING ITCT-2K2
May 17
Neither observations nor models show much variability; Asian pollution enhancement (6 ± 2 ppbv in GEOS-CHEM) is significant but undetectable
Goldstein et al. [2004]
CALIFORNIA MOUNTAIN SITES ARE PARTICULARLY CALIFORNIA MOUNTAIN SITES ARE PARTICULARLY SENSITIVE TO ASIAN OZONE POLLUTIONSENSITIVE TO ASIAN OZONE POLLUTION
…because there is less dilution…because there is less dilutionObserved 8-h ozone at Sequoia National Park (1800 m) in May 2002
vs. corresponding simulated (GEOS-CHEM) Asian pollution ozone enhancement
Asian enhancements are 6-10 ppbvduring NAAQS exceedances;unlike at surface sites, Asian pollution influence is not minimum under high-ozone conditions!
May 17 obs. Asian plume event in red
Hudman et al. [2004]
IMPORTANCE OF METHANE FOR THE IMPORTANCE OF METHANE FOR THE TROPOSPHERIC OZONE BACKGROUNDTROPOSPHERIC OZONE BACKGROUND
240
250
260
270
280
290
300
310
320
3301995 base case
50% methane
50% NOx
50% NMVOCs
50%NOx+NMVOCs50% CO
50% all
natural
Fiore et al., [2002b]
Sensitivity of global tropospheric ozone inventory (Tg) in GEOS-CHEM to 50% global reductions in anthropogenic emissions: NOx and methane have the greatest impacts
Anthropogenic methane causes another 4- 6 ppbv enhancement in surface ozone over U.S.
OBSERVATIONS OF INTERCONTINENTAL TRANSPORTOBSERVATIONS OF INTERCONTINENTAL TRANSPORTDURING ICARTT AIRCRAFT CAMPAIGN (Jul-Aug 2004)DURING ICARTT AIRCRAFT CAMPAIGN (Jul-Aug 2004)
AIRS satellite observations GEOS-CHEM near real time simulation
Asianpollution
U.S. pollution
Alaskan fires
Wallace McMillan (UMBC) Solene Turquety (Harvard)
Carbon monoxide (CO) columns on July 18
ASIAN POLLUTION PLUME OFF CALIFORNIAASIAN POLLUTION PLUME OFF CALIFORNIAsampled by NASA aircraft on July 1, 2004
GEOS forecast Asian CO (9 km) AIRS satellite CO data
Asianpollution
S. Pawson (NASA), W. McMillan (UMBC), M/ Avery (NASA), S.Turquety (Harvard). L. Jaegle (UW)
ASIAN POLLUTION PLUME ASIAN POLLUTION PLUME OVER EASTERN U.S.OVER EASTERN U.S.
sampled by NASA aircraft on July 15
Observed O3 = 20-40 ppbv, CO = 20 ppbvGEOS-CHEM O3 = 5-10 ppbv, CO = 10-20 ppbv
High Halon-1211 in plume confirms Asian origin
0
1
2
3
4
5
6
7
8
13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00 21:00
H-1
21
1 (
pp
tv)
0
5000
10000
15000
20000
25000
30000
35000
40000
Alt
itu
de
(ft
)
GEOS forecast Asian CO (9 km)
Observed O3 (ppbv)
Observed CO (ppbv)
POLICY-RELEVANT OZONE BACKGROUND (PRB) POLICY-RELEVANT OZONE BACKGROUND (PRB) USED FOR SETTING OF U.S. NAAQSUSED FOR SETTING OF U.S. NAAQS
NAAQS(8-h avg.)
0 20 40 60 80 ppbv
Naturalbackground
Present –daybackground at
northern midlatitudes
PRB is defined as the ozone concentration that would be present in absence of North American anthropogenic emissions
PRB used for present NAAQS
Risk increment
Frequent observations at remote U.S.sites attributed by Lefohn et al. [2001] to natural background…and used to
argue that NAAQS is unattainable
Can natural background indeed be so high as to make current standard unattainable?
Ozone time series at CASTNet sites used by Lefohn et al. [2001]Ozone time series at CASTNet sites used by Lefohn et al. [2001]
At low-elevation sites: background = 20-35 ppbv, natural = 10-25 ppbv
Fiore et al. [2003]
+
* Observations (1-5 pm average)
Background (no anthrop. emissions in N. America, present methane)
Natural (no anthrop. emissions globally, preindustrial methane)
Model: Base (2001)
Stratospheric influence
Occurrences of high valuesreflect either regional pollutionor a high-altitude site
BACKGROUND OZONE IS DEPLETED IN POLLUTION EPISODESBACKGROUND OZONE IS DEPLETED IN POLLUTION EPISODES
CASTNet sitesModelBackgroundNaturalStratospheric
+
*
Background on polluted days is 20-25 ppbv, below current PRB of 40 ppbv Current NAAQS underestimates health risks and is in fact too high
Ozo
ne
(pp
bv)
Cumulative Probability
RegionalPollution
Daily mean afternoon O3 at 58 U.S. CASTNet sites
June-July-August
Fiore et al. [2003]
ATMOSPHERIC PARTICULATE MATTER (AEROSOLS)ATMOSPHERIC PARTICULATE MATTER (AEROSOLS)
Soil dustSea salt
Aerosol: dispersed condensed matter suspended in a gasSize range: 0.001 m (molecular cluster) to 100 m (small raindrop)
SO2, NOx,NH3, VOCs
Most important components of the atmospheric aerosol:-Sulfate- nitrate-ammonium-Organic carbon (OC), elemental carbon (EC)-Soil dust-Sea salt
AIRCRAFT OBSERVATIONS IN ASIAN WARM CONVEYOR BELT (WCB) AIRCRAFT OBSERVATIONS IN ASIAN WARM CONVEYOR BELT (WCB) OUTFLOW ILLUSTRATE SCAVENGING OF AEROSOLS OUTFLOW ILLUSTRATE SCAVENGING OF AEROSOLS
DURING LIFTING TO FREE TROPOSPHEREDURING LIFTING TO FREE TROPOSPHERE
LongitudeData from E.V. Browell
boundary layer outflow
WCB outflow
Ozone:WCBoutflow
Aerosolsscavengedfrom WCBoutflow
TRACE-P campaign, spring 2001
GEOS-CHEM SIMULATION OF TRACE-P OBSERVATIONSGEOS-CHEM SIMULATION OF TRACE-P OBSERVATIONS
BC underestimated by factor of 2 because emissions [Bond et al.] are too low
Park et al. [2004b]
P3B DATA over NW Pacific (30 – 45oN, 120 – 140oE)
Scavenging from Asian outflow is 80-90% efficient for sulfate and BC, ~100% for nitrate
Black carbon(BC)
DUST STORMS PROVIDE VISIBLE EVIDENCEDUST STORMS PROVIDE VISIBLE EVIDENCEOF INTERCONTINENTAL TRANSPORT OF AEROSOLS OF INTERCONTINENTAL TRANSPORT OF AEROSOLS
GlenCanyon, AZ
Clear day April 16, 2001: Asian dust!
…and anthropogenic pollution is transported together with the dust
Colette Heald et al. (Harvard)
satellite data satellite data
ASIAN AEROSOL POLLUTION INFLUENCE ASIAN AEROSOL POLLUTION INFLUENCE OVER WESTERN U.S. OVER WESTERN U.S.
-*- AERONET__GEOS-CHEM __ Asian SO4
2-+NH4++NO3
-
__ Asian dust
Spring 2001
AERONET aerosol optical depth (AOD) measurements at Missoula, MT
Colette Heald et al. (Harvard)
AO
D
MEAN ASIAN POLLUTION INFLUENCES ON SURFACE MEAN ASIAN POLLUTION INFLUENCES ON SURFACE AEROSOL CONCENTRATIONSAEROSOL CONCENTRATIONS
Annual means determined from a GEOS-CHEM 2001 sensitivity simulation with Asian anthropogenic sources shut off
Park et al. [2004a]
SO42-
NO3-
NH4+
g m-3
Enhancements are low relative to air quality standard (15 g m-3)
EPA REGIONAL HAZE RULEEPA REGIONAL HAZE RULE
Requires linear improvement in visibility over 2004-2018 at federal class I areas (large national parks) toward a 2064 natural visibility endpoint
Visibility is a logarithmic function of aerosol extinction ~50% reduction in anthropogenic emissions required by 2018, sensitive to the definition of the 2064 endpoint
deciviews: dv = 10ln(bext/10), where bext is aerosol extinction
from EPA [2001]
VISIBILITY DEGRADATION STATISTICS IN THE UNITED VISIBILITY DEGRADATION STATISTICS IN THE UNITED STATES (2001): MODEL vs. OBSERVATIONSSTATES (2001): MODEL vs. OBSERVATIONS
Visibility decrease (deciviews: dv = 10ln(bext/10) )from sulfate, nitrate, and carbonaceous aerosols
R.J. Park (Harvard)
Observations (IMPROVE network) GEOS-CHEM
EPA “NATURAL DEFAULT CONCENTRATIONS” FOR THE EPA “NATURAL DEFAULT CONCENTRATIONS” FOR THE REGIONAL HAZE RULE ARE TOO LOWREGIONAL HAZE RULE ARE TOO LOW
00.20.40.60.8
11.21.41.61.8
Sulfate OrganicCarbon
2004 baseline
EPA natural default
Natural (our work)
Background (incl.transboundarypollution)
g m
-3
Western U.S.
…and don’t allow for large enhancement from transboundary pollution
Park et al. [2004a]
IMPLICATIONS FOR EMISSION REDUCTIONS IN PHASE 1 (2004-2018)IMPLICATIONS FOR EMISSION REDUCTIONS IN PHASE 1 (2004-2018) IMPLEMENTATION OF REGIONAL HAZE RULE IMPLEMENTATION OF REGIONAL HAZE RULE
Illustrative calculation for mean western U.S. conditions, assuming linear relationship between emissions and PM concentrations, and assuming constant anthropogenic sources from foreign countries between now and 2064
Desired trend in visibility
Required % decrease of U.S. anthropogenic emissions
Phase 1
30%
48%
Park et al. [2004]
WHERE ARE ASIAN EMISSIONS HEADED?WHERE ARE ASIAN EMISSIONS HEADED?It’s anyone’s guessIt’s anyone’s guess
Past trends and future projections of Chinese SO2 emissions [Streets et al., 2002]
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