Application of a unified aerosol-chemistry-climate GCM to understand the effects of changing climate and global anthropogenic emissions on U.S. air quality

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Application of a unified aerosol-chemistry-climate
GCM to understand the effects of changing
climate and global anthropogenic emissions on
U.S. air quality
How will a changing climate affect surface
concentrations of O3 and PM in the United States?

• PI Daniel J. Jacob, Harvard University
• Co-Is Joshua S. Fu, Univ. of Tennessee
• Loretta J. Mickley, Harvard University
• David Rind, GISS
• John H. Seinfeld, Caltech
• David J. Streets, Argonne

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GCMs are the necessary tools to predict the
response of air quality to future climate change

• Past model studies of the effects of climate
  change on AQ have focused on partial-derivative
  perturbations to meteorological variables, e.g.,
• But the perturbations to different
  meteorological variables are inherently
  correlated, and the most important perturbation
  for AQ is likely to be the change in circulation.
  Only a GCM can make predictions of the effects
  of climate change on AQ (partial-derivative
  studies are useful as diagnostic)
• GCMs have never been applied to investigate the
  effects of climate change on air pollution
  meteorology. We are in uncharted territory!

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MAJOR CHALLENGE IN APPLYING GCM TO 2000-2050 AQ
TRENDS separating climate change from
interannual variability in weather
Illustration change in global surface T in GISS
GCM climate equilibrium simulations with present
vs. preindustrial tropospheric ozone
present-day ozone
DF 0.46 W m-2
Preindustrial ozone
Mickley et al. 2003

• 1950-2050 time-dependent GCM calculation
• At least a 5-year sample of any climate regime

Need
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Interannual variability is even more of a problem
at regional scales
GISS GCM equilibrium Jun-Aug DT due to change in
tropospheric ozone over past century (DF 0.46 W
m-2)
GCM interannual variability Jun-Aug DT, Dcloud,
Dprecip over N. Mexico
DT (mean 1.4oC)
Dlowcloud (mean 2)
Dprecip (mean -0.5 mm/h)
How many years of simulation are needed? TBD, but
get guidance from present-day AQ statistics
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CHARACTERIZING AQ CLIMATOLOGY WITH NORMAL MODES
(PRINCIPAL COMPONENTS OR EOFs)
EOFs for surface 1-5 pm ozone in eastern U.S.,
Jun-Aug 1995
OBS (AIRS)
MAQSIP (36 km2)
EOF 1 East-west
r2 0.60 Slope 0.9
r2 0.86 Slope 1.0
r2 0.57 Slope 0.8
EOF 2 Midwest- Northeast
r2 0.76 Slope 1.0
r2 0.68 Slope 0.7
EOF 3 Southeast
r2 0.80 Slope 1.0
Fiore et al., in press, JGR
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SAME FUNDAMENTAL SYNOPTIC PROCESSES DRIVE OZONE
VARIABILITY IN GLOBAL MODEL
EOFs for surface 1-5 pm ozone, Jun-Aug 1995
OBS (AIRS)
GEOS-CHEM 2x2.5
EOF 1 East-west
r2 0.68 Slope 1.0
r2 0.74 Slope 1.2
EOF 2 Midwest- Northeast
r2 0.54 Slope 0.8
r2 0.27 Slope 1.0
r2 0.78 Slope 1.0
EOF 3 Southeast
r2 0.90 Slope 1.0
Fiore et al., in press, JGR
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INTERCONTINENTAL TRANSPORT OF POLLUTION
Asian influence likely to increase in future
what will be the effect of climate change?
Surface ozone enhancements from anthropogenic
emissions in northern midlatitudes continents
(GEOS-CHEM, JJA 1997)
North America
Europe
Asia
Li et al., JGR 2002
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TRANSATLANTIC TRANSPORT OF POLLUTIONcorrelation
with North Atlantic Oscillation Index
NAOI normalized surface pressure anomaly between
Iceland and Azores
North American ozone pollution enhancement at
Mace Head, Ireland (GEOS-CHEM)
North Atlantic Oscillation (NAO) Index
r 0.57
Greenhouse warming a NAO index shift a change in
transatlantic

transport of pollution
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PROJECT OBJECTIVES

• To quantify the effect of expected 2000-2050
  climate change on AQ in the U.S., independent of
  changes in anthropogenic emissions
• To quantify the combined effect of 2000-2050
  changes in climate and anthropogenic emissions on
  AQ in the U.S.
• To examine how climate change will affect
  intercontinental transport of pollution to the
  U.S.
• To define the normal modes (EOFs) of ozone and PM
  over the U.S., and examine whether the effect of
  climate change can be expressed as a perturbation
  to the structure and frequency of these modes
• To nest CMAQ within a unified aerosol-chemistry-cl
  imate GCM for more accurate simulation of
  regional air pollution in future climate.

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PROJECT HERITAGE 1 CHEMISTRY, AEROSOLS, AND
CLIMATETROPOSPHERIC UNIFIED SIMULATION (CACTUS)
NASA Interdisciplinary Science (IDS)
investigation Harvard (Jacob, Mickley), Caltech
(Seinfeld), GISS (Rind), UCI (Prather), CMU
(Adams), GIT (Nenes)
CACTUS model
Atmospheric chemistry

• emissions
• land use
• climate forcing

GISS GCM
Aerosol microphysics
Current version of CACTUS model incorporates
coupled ozone-PM chemistry in GISS GCM (4ox5o, 9
layers) Liao et al., JGR 2003. PM microphysics
developed separately (Adams and Seinfeld, JGR, in
press).

• D climate
• chemistry

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PROJECT HERITAGE 2INTERCONTINENTAL TRANSPORT
OF AIR POLLUTION (ICAP)
EPA/OAQPS and EPA/ORD project among others
Harvard (Jacob), Argonne (Streets), U. Houston
(Byun)

• Phase I (2002-2003) apply GEOS-CHEM CTM to
  simulate effects of future changes in emissions
  on U.S. ozone AQ with present climate
• Key result double dividend of methane control
  for climate stabilization and air quality Fiore
  et al., GRL 2002
• Phase II (2003-2004)
• Develop coupled ozone-PM-mercury simulation in
  GEOS-CHEM to serve as outer nest for CMAQ
• Ozone-PM coupling completed Martin et al., JGR
  2003 Park et al., JGR in press, mercury in
  development
• GEOS-CHEM/CMAQ coupling in development (with D.
  Buyn)
• Conduct preliminary investigation of effects of
  climate change on air pollution meteorology using
  9-layer GISS GCM simulations of CO and soot
  tracers
• 1950-2050 simulation is in progress

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PROJECT APPROACH

• Conduct 1950-2050 climate change simulations in
  CACTUS GCM
• GISS GCM w/4ox5o horiz resolution, 23 layers in
  vertical, q-flux ocean
• Chemical tracers (CO and soot) transported in
  model
• IPCC scenarios A1 and B1
• Analysis
• Trends in air pollution meteorological variables
  (T, humidity, PBL height, clouds)
• Trends in ventilation, circulation, scavenging
  using chemical tracers as diagnostics
• Assessment of n of simulation years needed for
  climate statistics

• 2. Conduct global ozone-PM simulations for
  present, 2030, and 2050 climates
• Use CACTUS GCM or GEOS-CHEM CTM (driven by GISS
  GCM meteorology) for n-year coupled ozone-PM
  simulations for the three climates.
• Conduct simulations with (1) present-day
  emissions, (2) modified climate-dependent natural
  emissions, (3) modified anthropogenic emissions
• Analysis
• Evaluate present-day simulation with
  observations, including EOFs for ozone and PM
• Diagnose changes in ozone and PM through
  statistical analysis including EOFs
• Diagnose changes in intercontinental transport
  of pollution

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PROJECT APPROACH (cont.)

• 3. Interface CACTUS GCM (or GEOS-CHEM CTM) with
  CMAQ for improved simulation of regional
  pollution including episodes
• Build model interface including GISS g MM5
  meteorology
• Conduct a 1-year simulation for 2050 climate
  over scale of continental U.S. (36 km2
  resolution) choose polluted year
• Analysis
• Diagnose regional pollution episodes and
  ozone/PM concentration statistics

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PROJECT TEAM AND RESPONSIBILITIES

• Harvard (Jacob/Mickley) project leadership, GCM
  and ozone-PM simulations, EOF analysis
• Caltech (Seinfeld) integration of PM simulation
  into updated CACTUS model, analysis of PM results
• GISS (Rind) GCM support, analysis of
  climate-driven changes in air pollution
  meteorology
• Argonne (Streets) global and U.S. inventories of
  ozone and PM precursors, primary PM
• Tennessee (Fu) interface of CACTUS with CMAQ,
  CMAQ simulation for 2050 climate