Download PPT - Atmospheric Chemistry Modeling Group

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
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., [O3 ]/ T
• 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!
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
equilibrium
present-day ozone
climate
DF = 0.46 W m-2
Preindustrial ozone
DT = 0.3oC
Mickley et al. [2003]
Need: • 1950-2050 time-dependent GCM calculation
• At least a 5-year sample of any climate regime
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
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)
EOF 1:
East-west
r2 = 0.86
Slope = 1.0
EOF 2:
MidwestNortheast
r2 = 0.76
Slope = 1.0
EOF 3:
Southeast
r2 = 0.80
Slope = 1.0
MAQSIP (36 km2)
r2 = 0.60
Slope = 0.9
r2 = 0.57
Slope = 0.8
r2 = 0.68
Slope = 0.7
Fiore et al., in press, JGR
SAME FUNDAMENTAL SYNOPTIC PROCESSES DRIVE
OZONE VARIABILITY IN GLOBAL MODEL
EOFs for surface 1-5 pm ozone, Jun-Aug 1995
OBS (AIRS)
EOF 1:
East-west
r2 = 0.74
Slope = 1.2
EOF 2:
MidwestNortheast
GEOS-CHEM 2°x2.5°
r2 = 0.68
Slope = 1.0
r2 = 0.54
Slope = 0.8
r2 = 0.27
Slope = 1.0
EOF 3:
Southeast
r2 = 0.90
Slope = 1.0
r2 = 0.78
Slope = 1.0
Fiore et al., in press, JGR
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
TRANSATLANTIC TRANSPORT OF POLLUTION:
correlation 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
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-climate GCM for
more accurate simulation of regional air pollution in future climate.
PROJECT HERITAGE #1:
CHEMISTRY, AEROSOLS, AND CLIMATE:
TROPOSPHERIC UNIFIED SIMULATION (CACTUS)
NASA Interdisciplinary Science (IDS) investigation: Harvard (Jacob, Mickley), Caltech
(Seinfeld), GISS (Rind), UCI (Prather), CMU (Adams), GIT (Nenes)
Demissions
D land use
D climate forcing
Atmospheric
chemistry
CACTUS model
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
D chemistry
PROJECT HERITAGE #2:
INTERCONTINENTAL 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):
1. 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)
2. 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
PROJECT APPROACH
1. 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
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
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