10th Annual CMAS Conference
24-26th October, 2011
Evaluation of effects of stratospheric
ozone to surface background ozone
Yun Fat Lam, Joshua Fu, Yang Gao*
Daniel J. Jacob**
Carey Jang and Pat Dolwick***
*The University of Tennessee, Knoxville
**Harvard University
***Office Air Quality Planning and Standards (OAQPS), USEPA
Oct 26, 2011
GEOS-Chem v8-02-03 configurations
• Domain:
Global simulation
• Horizontal Grid Spacing:
2 ° x 2.5°
• Horizontal Coordinate:
Lat x Lon
• Vertical Grid Spacing:
48 layers
• Simulation Period:
• Meteorological Input:
2006 - 2008
Assimilated meteorological
data from NASA GEOS-5
Emissions as shown below:
Observation comparison in US - ozone
• Ozone Network:
CASTNET
• Site Selection:
12 sites from Western US and
12 sites from Eastern US
• Summary Statistics: Western US (Avg. elevation: 2400 m)
Eastern US (Avg. elevation: 500 m)
MDA8 ozone in the Western US
MDA8 ozone in the Eastern US
MDA8 ozone (both Eastern and Western
sites)
It is a seasonal average value from March to September
Model - Observed
10.0
2007
2008
5.0
0.0
-5.0
Pinedale, WY
Horton Station, VA
-10.0
-15.0
Connecticut Hill, NY
Arendtsville, PA
Prince Edward, VA
Laurel Hill, PA
Parsons, WV
Horton Station, VA
Cranberry, NC
Cedar Creek, WV
Great Smoky NP, TN
Georgia Station, GA
Sand Mountain, AL
Rock Mtn NP, CO
Gentennial, WY
Eastern US
Mesa Verde NP, CO
Chiricahua NM, AZ
Pinedale, WY
CanyonLands NP, UT
Petrified Forest, AZ
Yellowstone NP, WY
Western US
Grand Canyon NP, AZ
-20.0
Great Basin NP, NV
Average of MDA8 Ozone Error (ppbv)
2006
Great Smoky NP, TN Yellowstone NP, WY
The resolution used in the GEOS-Chem simulation is not fine enough to
capture the MDA8 ozone at the bottom of the ridges.
If not counting those sites, the bias range is ~ ± 5 ppbv
MDA8 ozone (both Eastern and Western sites)
The GEOS-Chem under predicts the MDA8 ozone by 3.0 to 6.0 pbbv due
to the coarse grid resolution.
The interannual variation of MDA8 ozone is about 3.0 to 5.0 ppbv.
The Western US has a higher interannual variation (5.0 ppbv) than the
Eastern US (3.0 ppbv).
Study of US background ozone - 2006
• Confirmation of
Intercontinental transport of
air pollutants
• Enhancement of background
pollutants concentrations
•
Focus on Maximum Daily
Average 8-hr (MDA8) ozone
MDA8 ozone in the Western US
At the high elevation, 14.0 ppbv of overall MDA8 ozone is contributed by
anthropogenic emissions (about 25%). The average background is 40.0 ppbv.
MDA8 ozone in the Eastern US
At the low elevation, 25.0 ppbv of overall MDA8 ozone is contributed by
anthropogenic emissions (about 50%). The average background is 24.0 ppbv.
Background ozone in the spring
The background ozone at the elevated areas is much higher than in the low
areas (differences in the transport of stratospheric ozone). Additional 8.0 to 11.0
ppbv is observed in the Western background.
Background ozone in the summer
In the summer, the background ozone is increased by 3.0 ppbv in the Western
US due to the increase in temperature, while it decreased by 5.0 ppbv in the
Eastern US.
The contribution from anthropogenic emissions can reach as hig as 38.0 ppbv
predicted in the Northeastern US (see the blue plot) in summer.
Overall background ozone
1)
2)
The emission impacts from Canada and
Mexico only showed localized impacts.
The impact from Asia shows a
regional/continental impact
(3 – 5 ppbv increase in MDA8 ozone).
Development of GEOS-Chem to CMAQ
Initial and boundary conditions module
(Geo2CMAQ)
• First version – 2005 to 2006
(version 1.1-1.2)
–
Chemical Mapping Table for CB-IV and SPARC-99
Mechanisms (EPA, 2003)
–
Horizontal Interpolations between gridded models
–
Vertical Interpolation between layers
–
Added Chemical Mapping Table for CB-05 and
AE3 species
• Second version – 2008 (version 2.1)
–
Added tropopause determining algorithm to remove
stratospheric effects from GEOS-Chem (AE4)
• Newest version – 2010 (version 2.2)
–
–
Add new mapping table for CB05-AE5.
Restructure to accept output from GEOS-Chem v802-01.
Systematic flowchart of GEOS2CMAQ
(a) IC
Lam and Fu [2010]
Examples of CMAQ IC
and BC files (2006 July 01
at 0:00 GMT at surface)
Summary
•
The interannual variation in MDA8 ozone is about 3.0
to 5.0 ppbv among those three years.
•
The Western US shows a much higher background
ozone than the Eastern US, which is highly related to
the ozone transport from stratosphere.
•
The impact from Asia emissions is regional or
continental. The average impact is about 3 – 5 ppbv.
•
The emission impacts from Canada and Mexico only
showed localized impacts.
Thanks!
Questions?
This research was supported by USEPA and an allocation of advanced
computing resources provided by the National Science Foundation. The
computations were performed on Kraken at the National Institute for
Computational Sciences (http://www.nics.tennessee.edu/).