1. INTERCONTINENTAL TRANSPORT OF TROPOSPHERIC OZONE AND PRECURSORS AT NORTHERN MIDLATITUDES: IMPLICATIONS FOR SURFACE AIR QUALITY AND GLOBAL CHANGE
Daniel J. Jacob, Arlene M. Fiore, Qinbin Li, Randall V. Martin, Loretta J. Mickley, Paul I. Palmer, Rokjin Park

2. OZONE TREND AT EUROPEAN MOUNTAIN SITES, 1870-1990
Marenco et al. [1994]
Preindustrial
ozone models }

3. radiative forcing from tropospheric ozone is less well constrained than implied by IPCC 2001 report (and could be greatly underestimated)
Global simulation of late 19th century ozone observations with the GISS GCM
Standard model:
DF = 0.44 W m-2
“Adjusted” model
(lightning and soil NOx decreased,
biogenic hydrocarbons increased):
DF = 0.80 W m-2
[Mickley et al., 2001]

4. GLOBAL MEAN TEMPERATURE CHANGE SINCE 1750 DRIVEN BY MODEL TROPOSPHERIC OZONE CHANGE
and compared to temperature changes from equal radiative forcings (0.45 W m-2) by uniformly mixed ozone and CO2 (GISS GCM 2’)
Compared to an equivalent CO2 radiative forcing,
tropospheric ozone gives less tropospheric warming and more stratospheric cooling
CO2
Uniform
ozone
Ozone
Loretta Mickley,
In preparation

5. SURFACE OZONE IN U.S. INCLUDES A ppbv BACKGROUND THAT HAS INCREASED BY ~3 ppbv OVER THE PAST 20 YEARS
8-h daily maximum ozone probability distribution at rural U.S. sites
[Lin et al., 2000]

6. THIS OZONE BACKGROUND IS A SIZABLE INCREMENT TOWARDS VIOLATION OF U. S
THIS OZONE BACKGROUND IS A SIZABLE INCREMENT TOWARDS VIOLATION OF U.S. AIR QUALITY STANDARDS (even more so in Europe!)
Europe
(8-h avg.)
Europe
(seasonal)
U.S.
(8-h avg.)
U.S.
(1-h avg.)
ppbv
preindustrial
present
background

7. Simulated increase in mean U. S
Simulated increase in mean U.S. surface ozone (ppbv) from tripling of Asian emissions (1985 to 2015) with other emissions held constant
Enough to offset the benefits of 25% reductions in domestic emissions!
Jacob et al. [1999]

8. GEOS-CHEM global model of tropospheric chemistry (www-as. harvard
GEOS-CHEM global model of tropospheric chemistry (www-as.harvard.edu/chemistry/trop/geos)
assimilated meteorological data from NASA DAO,
1ox1o- 4ox5o horizontal resolution, layers in vertical
used by groups at Harvard, Duke, U. Washington, Rutgers, JPL, BNL, EPFL, Toulouse, Aquila; standard versions and benchmarks maintained at Harvard
RECENT AND CURRENT APPLICATIONS:
Tropospheric ozone : global budget, Asian outflow, U.S. air quality, Middle East, transatlantic transport, tropics (TOMS), interannual variability, trends
Carbon monoxide: global and regional budgets, interannual variability
Aerosols: sulfate-organics-dust-sea salt
Stratospheric ozone: coupling with troposphere
Carbon dioxide: source/sink information from correlations with chemical tracers
Organics: budgets of hydrocarbons, oxygenated organics, nitriles, methyl halides
Satellite retrievals, inversions, chemical data assimilation: CO, CO2, ozone, formaldehyde, NO2
Chemical forecasting: TRACE-P

9. SUMMER 1995 AFTERNOON OZONE IN SURFACE AIR
Fiore et al. [2001]
AIRS observations
GEOS-CHEM
(r2 = 0.4, bias=3 ppbv)
“Background ozone” produced outside the North American boundary layer
contributes ppbv to mean surface air concentrations in the model

10. OZONE BACKGROUND OVER U. S
OZONE BACKGROUND OVER U.S. IS GENERALLY DEPLETED DURING REGIONAL POLLUTION EPISODES due to deposition and chemical loss under stagnant conditions
Observed (J.W. Munger)
model (GEOS-CHEM)
model background
O3 vs. (NOy-NOx)
At Harvard Forest,
Massachusetts
Background
(clean conditions)
Background
(pollution episodes)
Fiore et al. [2001]
Pollution coordinate

11. RANGE OF ASIAN/EUROPEAN POLLUTION SURFACE OZONE ENHANCEMENTS OVER THE U.S. IN SUMMER as determined from a simulation with these emissions shut off
Subsidence of Asian pollution
+ local production
Max Asian/European pollution enhancements
(up to 14 ppbv) occur at intermediate ozone levels (50-70 ppbv)
stagnation
tropical
air
MAJOR CONCERN
IF OZONE STANDARD
WERE TO DECREASE!
Fiore et al. [2001]

12. NORTH AMERICAN OZONE OUTFLOW IN SURFACE AIR (GEOS-CHEM model results for 1997)
APRIL H L
JULY H
Li et al. [2001]

13. ORIGIN OF SURFACE OZONE AT BERMUDA IN SPRING
(S. Oltmans)
Production over U.S. is the dominant source of ozone at Bermuda; stratosphere contributes less than 5 ppbv
Li et al. [2001]

14. OZONE DATA AT MACE HEAD, IRELAND
Model vs. observed
stats,
Time series, Mar-Aug 1997
Observed
[Simmonds]
GEOS-CHEM
model
N.America pollution
events in model
Li et al. [2001]

15. EFFECT OF NORTH AMERICAN SOURCES ON VIOLATIONS OF EUROPEAN AIR QUALITY STANDARD (55 ppbv, 8-h average)
GEOS-CHEM model
results, summer 1997
Number of
violation days
(out of 92)
# of violation days that
would not have been
in absence of
N.American emissions
Li et al. [2001]

16. FORECASTING TRANSATLANTIC TRANSPORT OF NORTH AMERICAN POLLUTION TO EUROPE WITH THE NORTH ATLANTIC OSCILLATION (NAO) INDEX
NAO index = normalized surface P anomaly between Iceland and Azores
NAO Index
North American ozone pollution enhancement
At Mace Head, Ireland (GEOS-CHEM model)
r = 0.57
Li et al.
[2001]
Greenhouse warming a NAO index shift a change in transatlantic
transport of pollution

17. SURFACE OZONE ENHANCEMENTS CAUSED BY ANTHROPOGENIC EMISSIONS FROM DIFFERENT CONTINENTS
GEOS-CHEM
model, July 1997
North America
Europe
Asia
Li et al. [2001]

18. INTERCONTINENTAL TRANSPORT: CONCENTRATIONS, FLUXES, BUDGETS
QUANTIFYING INTERCONTINENTAL TRANSPORT THROUGH INTEGRATION OF OBSERVATIONS AND MODELS
SATELLITE OBSERVATIONS
Global and continuous but
few species, low resolution
Source/sink
inventories
3-D CHEMICAL
TRACER MODELS
SURFACE OBSERVATIONS
high resolution but spatially limited
Assimilated
meteorological
data
AIRCRAFT OBSERVATIONS
High resolution, targeted flights
provide critical snapshots
for model testing
Chemical
and aerosol
processes
INTERCONTINENTAL TRANSPORT:
CONCENTRATIONS, FLUXES, BUDGETS

19. INTERCONTINENTAL TRANSPORT EXPERIMENT – NORTH AMERICA (INTEX-NA)
A NASA Global Tropospheric Experiment (GTE) mission
OBJECTIVES:
To quantify the North American import and export of
(1) atmospheric oxidants and their precursors, (2) aerosols and their precursors, (3) long-lived greenhouse gases
To relate this import/export to surface sources/sinks and to continental boundary layer chemistry
TWO AIRCRAFT: NASA DC-8 and P-3
TWO PHASES:
Summer 2004:
active photochemistry, biosphere
aerosol radiative forcing
carbon uptake
Spring 2006:
maximum Asian inflow
contrast with summer

20. INTEX NOMINAL FLIGHT TRACKS FOR PHASE A (SUMMER)RL BG WL AZ DR BR NO HI
DC-8
P-3B
Ozonesonde sites

21. ATMOSPHERIC COLUMNS OF NO2 AND FORMALDEHYDE (HCHO) MEASURED FROM GOME BY SOLAR BACKSCATTER ALLOW MAPPING OF NOx AND HYDROCARBON EMISSIONS
GOME SATELLITE
INSTRUMENT
Tropospheric NO2 column ~ ENOx
Tropospheric HCHO column ~ ENMHC
~ 2 km
hn (420 nm)
BOUNDARY
LAYER
hn (340 nm)
NO2 NO
HCHO CO OH
hours
O3, RO2
hours
NMHC
1 day
HNO3
Emission
Deposition
Emission
NITROGEN OXIDES (NOx)
NON-METHANE HYDROCARBONS

22. CAN WE USE GOME TO ESTIMATE NOx EMISSIONS. TEST IN U. S
CAN WE USE GOME TO ESTIMATE NOx EMISSIONS? TEST IN U.S. WHERE GOOD A PRIORI EXISTS
Comparison of GOME retrieval (July 1996) to GEOS-CHEM model fields
using EPA emission inventory for NOx
GOME
GEOS-CHEM
(EPA emissions)
BIAS = +3%
R = 0.79
Martin et al. [2001]

23. GOME RETRIEVAL OF TROPOSPHERIC NO2 vs. GEOS-CHEM SIMULATION (July 1996)
Martin et al. [2001]
GEIA emissions
scaled to 1996

24. FORMALDEHYDE COLUMNS FROM GOME: July 1996 means
Palmer et al. [2001]
BIOGENIC ISOPRENE IS THE MAIN SOURCE OF HCHO IN U.S. IN SUMMER

25. GOME DETECTS THE ISOPRENE “VOLCANO” IN THE OZARKS
Palmer et al. [2001]

26. CORRELATION WITH SURFACE TEMPERATURE OF GOME HCHO COLUMNS OVER THE OZARKS
Temperature dependence
of isoprene emission (GEIA)
Palmer et al. [2001]

27. GOME GEIA (IGAC inventory) BEIS2 COMPARE TO…
MAPPING OF ISOPRENE EMISSIONS FOR JULY 1996 BY SCALING OF GOME FORMALDEHYDE COLUMNS [Palmer et al., 2001]
GOME
COMPARE TO…
GEIA (IGAC inventory)
BEIS2

28. ONGOING WORK AT HARVARD FOR PHASE I OF OAR/OAQPS CLIMATE CHANGE MODELING INITIATIVE (Arlene Fiore, Rokjin Park, Brendan Field, Daniel Jacob)
OBJECTIVES:
Determine the global impacts of future changes in anthropogenic emissions on
surface ozone in N. America, Europe, and Asia;
surface ozone background;
tropospheric oxidizing capacity;
radiative forcing (CH4 and O3).
Develop coupled ozone-aerosol simulation capability in GEOS-CHEM for nesting with CMAQ/Models-3
APPROACH:
Conduct global GEOS-CHEM simulations with
50% global reductions in emissions;
realistic future emission scenarios (Streets)
Implement GEOS aerosol simulation from Mian Chin (NASA/GSFC) into GEOS-CHEM model

29. IMPACTS OF 50% REDUCTIONS IN ANTHROPOGENIC EMISSIONS
Diagnostic
Standard
50% CH4
50% NOx
50% VOC
50% NOx & VOC
50% CO
50% All
Median U.S. summer
1-5 pm O3 (ppbv) 51 48 42 50 41 38
U.S. grid-square summer days
with 1-5 p.m. O3 >80 ppbv 37 17 26 27
with 1-5 p.m. O3 >60 ppbv
1190
704 96
1059 87
1085 29
Mean U.S. background O3 in summer (ppbv) 24 23 20
Global tropospheric O3 inventory (Tg)
321
294
300
317
297
269
Implied global CH4 concentration (ppbv)
1700
1000
1867
1685
1846
1643
1040
CH4 radiative forcing
(W m-2) --
-0.30
+0.06
-0.01
+0.05
-0.02
-0.28
O3 radiative forcing
-0.07
-0.06
-0.15
Wang & Jacob 1998: standard: 85 Tmol/yr Ox produced, OPE: 28, 3 Tmol/yr NOx (SAME)
Note additive effects of NOX & VOC runs
Simulations are for 7/94-12/95 (first 6 mos. for initialization) with 4ox5o resolution

30. NEXT STEP: NESTING OF GEOS-CHEM WITH MODELS-3 in collaboration with EPA/OAQPS and ORD
One-way nesting: use GEOS-CHEM global model fields as time-dependent boundary conditions for simulation of ozone, aerosols, and their precursors in Models-3
First application: Texas 2000 field campaign
Two-way nesting: develop better simulation of regional effects on global atmospheric chemistry including intercontinental transport and radiative forcing

31. SOME PRIORITY QUESTIONS FOR PHASE II OF OAR/OAQPS CLIMATE CHANGE MODELING INITIATIVE
How can we develop an integrated modeling framework to assess the effects of specific perturbations (e.g., anthropogenic emissions) on local surface air quality and global change in a consistent manner?
Development of nested aerosol-chemistry models
How can we design an observational strategy to evaluate model assessments of intercontinental transport?
Use models to define the observations needed to test them
How can we extract information from satellite observations on intercontinental transport of pollution?
Integration with in situ observations and models, development of inverse modeling tools
How can we better understand the climate forcings of ozone and aerosols?
Development of coupled aerosol-chemistry-climate models