Zhang et al., ACP 2014

22 Pages·2015·3.35 MB·English

by  Lin Zhang

Sources contributing to North American
background ozone in the western US
Lin Zhang
(Peking University)
With Daniel J. Jacob, and the Harvard Atmospheric Chemistry
Modeling Group
Session 3: Modeling of long-range ozone transport: implications for
western air districts and the US overall
Transboundary Ozone Pollution Conference
April 1, 2015
2
Long-range transport of ozone pollution to the western US
Springtime ozone profile
at Trinidad Head, CA
Stratosphere
Lightning
Transport of
anthropogenic
pollution
Wildfires
Local human activities
Black: measurements (baseline)
Green: model results
Red: North American background
(~5 ppbv lower than model)
(McDonald-Buller et al.,
AE 2011) Annual 4th highest North American background ozone for 2006-2008
3
TES and AIRS observations of a transpacific plume
TES GEOS-Chem AIRS CO columns
A
B
A
B
2006
(Zhang et
al., ACP
2008)
Ozone production in transpacific plumes
Mean for the INTEX-B period (April 17-May 15, 2006)
Enhanced gross ozone production from Asian emissions at 800 hPa
Differences of gross ozone production rates from the standard simulation and a sensitivity simulation
L
Sea level pressure
and 800 hPa winds
overplotted
H
 Direct transport of Asian ozone produced in the boundary layer and
continuous ozone formation over the Pacific (decomposition of PAN)
 Splitting of transpacific plumes over the northeast Pacific
(Zhang et al., ACP 2008)
Impact of rising Asian emissions on surface ozone
Data from Dan Jaffe (Univ. of Washington) 2006 surface Asian O enhancements
3
O measurements at Mt. Bachelor
3
(44oN, 122oW, 2.7 km, in central Oregon)
54 ± 10
53 ± 8
9.4 ± 2.5
O increase from 2000 to 2006
3
 Asian emissions increase surface ozone in the western US by 5-8 ppbv.
 Doubling Asian emissions from 2000 to 2006 increases surface ozone by 1-
2 ppbv in the west US.
(Zhang et al., ACP 2008)
Multiple model estimates of intercontinental ozone influences
Receptor = NA
21 chemical transport models

reported to TF HTAP (Task
Force on Hemispheric Transport
of Air Pollution)
±50% ranges among the

models
Receptor = EU Receptor = EA
(Fiore et al., JGR 2009)
GEOS-Chem ozone simulation at the western CASTNet sites
GEOS-Chem with the GEOS-5 native 1/2o x 2/3o resolution over North America and
adjacent oceans (140o-40oW, 10o-70oN), and 2ox2.5o resolution over rest of world.
Daily 8-h max ozone time series in spring - summer 2006
CASTNet ozone Numbers inset are the means and annual 4th highest values (in parentheses)
monitoring sites
(cid:9)
NA anthro.
10-22 ppbv
11-16 ppbv
Intercontinental
transport plus
anthro. CH
4
(cid:9)
8
(Zhang et al. AE 2011)
GEOS-Chem simulated vs. observed ozone exceedances
at the western sites
 Has some success at individual sites but fails to capture the exceedances
for the 65 and 70 ppbv thresholds in spring.
9
(Zhang et al. AE 2011)
Influences of lightning NO emissions on surface ozone
x
Lightning NO emissions constrained by NLDN
x
(cid:9)
Simulated ozone enhancements from
lightning emissions for summer 2007
Measurements GEOS-Chem (Zhang 2011)
GEOS-Chem (Zhang 2014) Δ lightning (cid:9)
 Using the NLDN data largely corrects
ozone overestimates over the Southwest
US in summer.
 6-8 ppbv ozone on average from lightning
with moderate variability.
(Zhang et al., ACP 2014)