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Diagnosing the sensitivity of O 3 air quality to climate change over the United States. Moeko Yoshitomi ([email protected]), Daniel J. Jacob, Loretta J. Mickley, Philippe Le Sager, Julia M. Sygiel, Shiliang Wu Department of Earth & Planetary Sciences Harvard University. - PowerPoint PPT Presentation
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Diagnosing the sensitivity ofO3 air quality
to climate changeover the United States
Moeko Yoshitomi ([email protected]),Daniel J. Jacob, Loretta J. Mickley,
Philippe Le Sager, Julia M. Sygiel, Shiliang Wu
Department of Earth & Planetary SciencesHarvard University
presented at GCAP Phase 2 Science Team MeetingHarvard University, MA, US
October 12th, 2007
[2] CMU CTM
Projecting Future O3 Air Quality in the US
[1] Harvard CTM[Wu et al., 2007]
Δ(2050s - present) in simulated summer daily 8-hr max O3 levels
[Racherla and Adams, 2006]
O3 [ppb]
・ Many regions show substantial future O3 increases (1-5 ppb) due to climate change・ Spatial patterns of climate-induced increases in O3 is different
- where the highest O3 is predicted - how much O3 increases at a maximum
[2] CMU CTM
Projecting Future O3 Air Quality in the US
[1] Harvard CTM[Wu et al., 2007]
Δ(2050s - present) in simulated summer daily 8-hr max O3 levels
[Racherla and Adams, 2006]
O3 [ppb]
Key issue: modeling of the fate of isoprene emissions over the SE
isopreneemission
Higher isoprene emissions in SE ⇒ O3 ↑ or ↓???
[10e-8 g C/m2/s] [g/s]
Isoprenek298=1.3x10-17
RONO2
(isoprene nitrate)
OH RO2
NO
Isoprene
NO2
k298=1.0x10-10
O3 ↑
O3 Products O3 ↓
Deposition
Uncertain NOx-Isoprene-O3 Chemistry
NO
O3 ↓
There is a controversial competition on isoprene effects on O3
branch ratio??branch ratio??
NOx recycled ??NOx recycled ??
Hourly surface O3 concentrations from AIRS/EPA and daily maximum temperatures from NCDC, for JJA 1980-1998, which is gridded at 4x5
Observations
[1] GCAP run at 4x5 resolution = GEOS-Chem + calculated GISS GCM meteorology (JJA 1999-2001)[2] GEOS-4 run at 2x2.5 resolution = GEOS-Chem + assimilated GEOS4/GMAO meteorology (JJA 1999-2001)
Model Simulations
Major Questions from Previous GCAP Research
1. Can we apply observed O3-temperature relationship to validate chemical models used to investigate the sensitivity of surface O3 to climate change?2. Is the O3-temperature relationship sensitive to assumptions about the fate of isoprene nitrate?
Understanding the Relationship of Surface O3 and Temperature
Reduced-major-axis (RMA) linear regression: to allow for errors in both x and y coordinates
Data Sets
・ Daily maximum of 8-hr running average O3 concentrations (MDA8)・ Daily maximum temperature
Regression Analysis on O3 and T
Approach
[For Question 1 & 2] Analyze the relationship in a gridbox-scale[For Question 2] Analyze the relationship in a regional scale (Northeast: 7 boxes, Southeast: 9 boxes, Midwest, Northwest, Southwest, Central, Mid-Atlantic)
From RMA linear regression
・ Sensitivity of O3 to temperature varies across the US・ The NE shows stronger O3/T correlation than the SE
Observed Correlation between O3 and T
-10 5 0 5 10
Correlation CoefficientSlope dO3/dT
-1 -.5 0 .5 1
From RMA linear regression
・ Sensitivity of O3 to temperature varies across the US・ The NE shows stronger O3/T correlation than the SE
Observed Correlation between O3 and T
-10 5 0 5 10
Correlation CoefficientSlope dO3/dT
-1 -.5 0 .5 1
SE NE
O3 and Temperature Observed by AIRS
Temperature has an inter-annual variability - 19-yr mean/1988 mean/1992 mean; NE: 300.53/302.14/298.79 [K],
SE: 305.92/306.10/305.26 [K]
280 300 320 280 300 320
280 300 320 T max [K]
280 300 320 T max [K]
150
100
50
0
150
100
50
0
150
100
50
0
MD
A8
[ppb
]
150
100
50
0
O3 and Temperature Simulated by GCAP
280 300 320
150
100
50
0
MD
A8
[ppb
]
280 300 320 T max [K]
150
100
50
0
280 300 320
150
100
50
0 280 300 320
150
100
50
0
MD
A8
[ppb
]
NE has stronger O3/T correlation than SE - GCAP O3/T correlations are slightly stronger in both NE and SE than
observed O3/T correlations
The GCAP results do not vary too much year-to-year
GCAP Model Captures Correlation Trends
-1 -.5 0 .5 1
1980-1998 obs 1999-2001 GCAP
1999-2001 GEOS4
・ GEOS4 does not show the difference between NE and SE that obs.
and GCAP model show
・ Sensitivity of O3 to temperature varies across the US in both obs. and models・ Both the observations and GCAP show stronger correlation in the NE than the SE
GCAP Captures the Variation in dO3/dT SlopeSlope of dO3/dT from RMA linear regression
-10 5 0 5 10
1980-1998 obs 1999-2001 GCAP
1999-2001 GEOS4
・ Cool Gulf of Mexico air with low-level O3 gives higher slopes in the SE; nothing to do with local chemistry・ GEOS4 does not show the difference between NE and SE that GCAP shows
[Short-term work]・ Explore reasons for the differences in O3-T correlation between obs. and models
- meteorology issue (e.g., difference between GCAP and GEOS4) - missing chemistry (e.g., isoprene sensitivity analysis)
・ Interpret whether the NE-SE contrast reflects transport or chemistry
[Long-term work]・ Estimate the sensitivity of ozone pollution to future global change with our GCAP model for each SRES scenario
・ Investigate effects of 2000-2050 changes in global anthropogenic emissions and in general circulation to the intercontinental transport of air pollutants to the US
My Future Work
GCAP Phase 2 Science Team meetingat Maxwell Dworkin 223
GCAP Phase 2 Science Team meetingat Maxwell Dworkin 223
GCAP Phase 2 Science Team meetingat Maxwell Dworkin 223
GCAP Phase 2 Science Team meetingat Maxwell Dworkin 223