Emerging issues in air quality
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Transcript of Emerging issues in air quality
Emerging issues in air quality
Daniel J. Jacob
with Lin Zhang, Raluca Ellis, Fabien Paulot, Eloise Marais, Qiaoqiao Wang, Kevin Wecht, Alex Turner, Helen Amos, Hannah Horowitz
and Anne Perring, Joshua Schwartz, David Fahey (NOAA), Cui Ge, Jun Wang (U. Nebraska), David Streets (Argonne)
Support from BP, NASA, NSF
4th-highest annual maximum of daily 8-h average ozone,2008-2010
Current standard: 75 ppbProposed standard: 60-70 ppb
Long-term surface ozone trendTrend in 95th percentile, June-August 1990-2010
Cooper et al. [2012]
• Decrease in eastern US driven by NOx emission controls;• Increase or flat in Intermountain West
4th-highest annual maximum for daily 8-h average ozone,2008-2010
Intermountain West: The next ozone frontier!
High elevation, arid terrain → high ozone background
Current standard: 75 ppbProposed standard: 60-70 ppb
High background and stratospheric intrusionsin Intermountain West
• Most surface ozone in Intermountain West originates from outside N America
• Highest ozone events (>80 ppb) due to stratospheric filaments, cannot be reproduced in models (stretched-flow numerical diffusion)
• Have to be careful with definition of stratospheric influence
2007
Zhang et al., in prep.
S
T
O3 producedin stratosphere
Two definitions ofstratospheric influence on tropospheric ozone:
O3 transportedfrom stratosphere
tropopause
Ozone at Gothic, Colorado (2,900m)
ObservedGEOS-Chem N Am background
Strat (transported)
Strat (produced)
Wildfire plumes alone do not drive high-ozone events
• No evidence of high-ozone events from fire plumes unless mixed with pollution
• Models generate excessive ozone because they don’t account for emissions of highly reactive VOCs that lock up NOx as PAN in the plume – a difficult problem!
• Fires can still contribute to background ozone through PAN decomposition
Glacier NP, 2007: model has high O3 in fire plumes, observations show none
Organic aerosol (OC) correlates with western US fires but not ozone
OC (IMPROVE)Ozone (CASTNet)
2006-2008
Zhang et al., in prep.
Observed GEOS-Chem wildfires
N deposition at US national parks: critical load exceedances
Ellis et al. [2013]
More deposition is expected to originate from ammonia in future
Critical loads are 3-5 kg N ha-1 a-1
depending on ecosystem
2006 2050
NOx
NH3
Present and future (RCP)US emissions
Future exceedances driven byammonia emissions
Ellis et al. [submitted]
2006
2050RCP2.6
Optimizing NH3 emissions by adjoint inversion of 2005-2008 NH4
+ wet deposition flux dataNADP data (circles) and GEOS-Chem model after adjoint inversion
April:fertilizer
July:livestock
kgN ha-1 month-1
Error correlation between NH4+ wet deposition flux (F) and precipitation (P)
obtained by GEOS-Chem simulations with GEOS-4 vs. GEOS-5 meteorology:
PGEOS5/PGEOS4
FG
EO
S5/
FG
EO
S4 0.6 power dependence
Paulot et al. [submitted]
Optimized ammonia emissions …and new MASAGE bottom-up ammonia emission inventory
US EU E Asia x 0.5
crops
livestock
other anthronatural
2.7 2.9 8.4
2.8 3.1 8.4 (China)
Paulot et al. [submitted]
N deposition from agriculture is a global pollution problem
Annual mean agricultural ammonia emissions from MASAGE (2005-2008)
63% are from countries outside the US, European Union, and China
Paulot et al. [submitted]
Contribution of US food export to PM (NH4NO3) air pollution
MASAGE NH3 emissions from food export
wheat
PM due to food export (GEOS-Chem)
annual
Economic implications by state ($ per capita):
Paulot et al., in prep
beef
corn
Next frontier for air pollution: NigeriaOMI formaldehyde2005-2009
MISR SCIA
aerosol (AOD) NO2 HCHO glyoxal methane
• Population: 270 million (+2.6% a-1)• GDP: $273 billion (+7% a-1) – oil!• Most natural gas is flared• >80% of domestic energy from biofuel, waste
LagosPortHarcourt
An unusual mix of very high VOCs, low NOx –What will happen as infrastructure develops?
Marais et al., in prep.
gasflaring!
1015 molecules cm-2
Multimodel intercomparison and comparison to
observations
Multimodel intercomparisons and comparisons to observations
Koch et al. [2009], Schwarz et al. [2010]
ARCTAS (Arctic spring)
BC, ng kg-1 BC, ng kg-1
TC4 (Costa Rica, summer)
ObservedModels
• Models differ by order of magnitude between themselves and with observations
• Large overestimates of observations over oceans,
upper troposphere
• Discrepancy must be driven by model errors in scavenging
Large model errors for black carbon (BC) aerosol in remote airP
ress
ure
, h
Pa
obsmodels60-80N
obsmodels20S-20N
Pre
ssu
re,
hP
a
HIPPO over Pacific (Jan)
BC, ng kg-1 BC, ng kg-1
Ensemble of AeroCom models
Global BC simulation in GEOS-ChemSource (2009): 4.9 Tg a-1 fuel + 1.6 Tg a-1 open fires Lifetime: 4.2 days
NMB= -27%
NMB= -12%
NMB= 6.6%
Observations (circles) and model (background)
surfacenetworks
AERONETBC AAOD
NMB= -32%
Aircraft profiles in continental/outflow regionsHIPPO(US)
Arctic(ARCTAS)
Asian outflow(A-FORCR)
US(HIPPO)
observedmodel
Successful simulation in source regions and outflow
Wan
g e
t al
., i
n p
rep
HIPPO BC curtains across the Central Pacific, 2009-2011
• Minima in deep tropics• Model doesn’t capture
low tail, is also too high at N mid-latitudes; median bias is factor of 2, mean column bias is +48%
Wang et al., in prep
Observations by Perring et al. (in prep.)
Observed Model PDF
PD
F, (
mg
m-3 S
TP
)-1
BC top-of-atmosphere direct radiative forcing (DRF)
EmissionTg C a-1
Global load(mg m-2)[% above 5 km]
BC AAODx100
Forcing efficiency(W m-2/AAOD)
Direct radiative forcing (W m-2)
This work 6.5 0.15 [8.7%] 0.17 88 0.15 (0.13-0.26)
AeroCom [2006]
7.8 ±0.4 0.28 ± 0.08[21±11%]
0.22±0.10 168 ± 53 0.34 ± 0.07
Chung et al. [2012]
0.77 84 0.65
Bond et al. [2013]
17 0.55 0.60 147 0.88
• In our work, BC above 5 km contributes 30% of global DRF and BC over the oceans contributes 24%; these contributions would be higher in other models with less efficient scavenging.
• We find that BC radiative forcing is much less than previously estimated; need to better understand BC in free/remote troposphere!
Wang et al., in prep
Constraints on US methane emissions from SCIAMACHY data
1700 1800ppb
SCIA CH4 column mixing ratio, Jul-Aug 2004
• Adjoint inversion with EDGAR v4.2 (anthropogenic), Kaplan (wetlands) as priors• Focus on INTEX-A mission period to validate SCIAMACHY data and inversion
0.5 1.51.0
Adjoint inversion scaling factors
Wecht et al. [in prep]Livestock Oil & Gas Waste Coal Mining Other
0
5
10
15Total US anthropogenic emissions (Tg a-1) EDGAR v4.2 26.6
EPA 28.3
This work 32.7
Methane from GOSAT: preliminary adjoint inversion
GOSAT data for CalNex period (May-Jul 10) Scaling factors to EDGAR inventory
• GOSAT data show consistency with SCIAMACHY for constraining livestock and wetland sources, but also discrepancies
• The data are sparse; now applying a Gaussian Mixture Model to optimally reduce the state vector for the inversion
Turner et al. [in progress]
Can we monitor from space the evolving source from oil & gas?
Biogeochemical cycle of mercury
Hg(0) Hg(II)
particulate
Hg
burial
SEDIMENTS
uplift
volcanoeserosion
oxidation
Hg(0) Hg(II)reduction biological
uptake
ANTHROPOGENIC PERTURBATION:fuel combustion
mining
ATMOSPHERE
OCEAN/SOIL
VOLATILE WATER-SOLUBLE
(months)lifetime~6 months
History of global anthropogenic Hg emissions
Large past (legacy) contribution from N. American and European emissions; Asian dominance is a recent phenomenon
Streets et al. , 2011
Global source contributions to Hg in present-day surface ocean
• Human activity has increased 7x the Hg content of the surface ocean
• Half of this human influence is from
pre-1950 emissions
• N America, Europe and Asia share similar responsibilities for anthropogenic Hg in present-day surface ocean
Amos et al., in press
EuropeAsia
N America
S America
former USSR
ROW
pre-1850natural
emissions
from biogeochemical box model constrained with GEOS-Chem fluxes
Disposal of Hg in commercial products:a missing component of the Hg biogeochemical cycle?
Global production of commercial Hg peaked in 1970
Horowitz et al., in prep
• Commercial Hg enters environment upon use or disposal; much larger source than inadvertent emission
• Could explain observed atmospheric decrease of Hg(0) over past two decades
Environmental release from commercial products dwarfs current emission estimates
TEMPO geostationary UV/Vis satellite instrumentselected in November 2012 for 2018/2019 launch
PI: Kelly Chance, Harvard-Smithsonian
• Monitoring of tropospheric ozone (2 levels), aerosols, NO2, SO2, formaldehyde, glyoxal with 1-hour temporal resolution, 4-km spatial resoution
• To be part of a geostationary constellation with other sensors observing Europe and East Asia
TEMPO Sentinel-4 GEMS
Next frontier in satellite observationsof atmospheric composition!