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Tropospheric O 3 budget of the South Atlantic region. B. Sauvage, R. V. Martin, A. van Donkelaar, I. Folkins, X.Liu, P. Palmer, V. Thouret , A. M. Thompson, P. Bernath & K. Chance. Picture: METEOSAT Oct 2000. Outstanding scientific issue in the Tropics. - PowerPoint PPT Presentation
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Picture: METEOSAT Oct 2000
Tropospheric OTropospheric O33 budget budget
of the of the
South Atlantic regionSouth Atlantic region
B. Sauvage,
R. V. Martin, A. van Donkelaar, I. Folkins, X.Liu, P. Palmer, V. Thouret , A. M. Thompson,
P. Bernath & K. Chance
Outstanding scientific issue in the TropicsOutstanding scientific issue in the Tropics
GOME Seasonal Tropospheric O3 Columns 2000DJF
MAM
JJA
SON
Topic: O3 maximum zonal wave-one (from Fishman et al. 1987… to Wang et al 2006)
Scientific interest:
year-round pattern observed since the 80’s. Situated in MT-UT O3 critical for radiative effect Key role on the oxidizing power of the atmosphere O3 maximum attributed to various anthropogenic and natural sources + dynamics
Goal:
What controls O3 maximum?
(Sources / regions)
data from Liu et al 2005DU
MethodologyMethodology
What controls
the O3 maximum?
High estimation emissions uncertainty
Global chemical transport model GEOS-Chem “Original” simulation
1
Constraint & Evaluation
In-situ & satellite observations
Lightning: spatial distribution scaled to OTD-LIS
Soils: a posteriori inventory of NOx from GOME (Jaeglé et al., 2005)
Biomass burning: top-down constraint on NOx & VOCs from GOME
2
Quantification (sources / regions)
O3 maximum
3Constrained
“standard” simulation
Space-based constraint on emissionsSpace-based constraint on emissions
NO
h
O3
NO2
HNO3Lifetime hoursVOC
OHHCHOh
hoursCO
hours
PBL
NOx VOC
Free Troposphere
NO NO2
O3, HO2
hv
HNO3
NOx lifetime ~ week
O3
lifetime ~ month
O3
lifetime ~ days
Tropospheric NO2 column ~ ENOx
Tropospheric HCHO column ~ EVOC GOME: 320x40 km2
OTD-LIS Lightning flash rates
Effect of satellite constraint in simulated tropospheric column O3Effect of satellite constraint in simulated tropospheric column O3
Δ Tropospheric O3 Columns “constrained” – “original ” simulationsDJF
MAM
JJA
SON
ΔDU
Large influence from lightning and biomass burning constraint
Space-based constraint on Space-based constraint on lightninglightning NO NOxx emissionsemissions
OTD-LIS flashes (1995-2004) local seasonal rescaling of lightning emissions
-Regional differences / oceanic emissions
-Same intensity: 5 Tg N yr-1
109 molec N cm-2 s-1
Original constrained with OTD/LIS
Modeled lightning NOx emissions (DJF)
In-situ OIn-situ O33, data used to evaluate the simulation, data used to evaluate the simulation
1.MOZAIC airborne program (Marenco et al., 1998; Thouret et al. 1998): 1994-2004 landing and taking off phase
2.SHADOZ ozone sonde network (Thompson et al., 2003a; 2003b): 1998-2004
More than 9000 vertical profiles of OMore than 9000 vertical profiles of O33 over the Tropics 30 over the Tropics 30°°N-30N-30°°SS
Highlights of simulation evaluation: sensitivity to Highlights of simulation evaluation: sensitivity to lightninglightning
Rescaling improve middle-upper tropospheric O3 from 5-15 ppbv
Main influence over subsident zone; South America; Middle East; East
Sensitivity to lightning intensity:7Tg N/yr too high; 3Tg N/yr too low; 5±2Tg N/yr gives overall agreement.
In-situ
constrained
GOME Model originalModel constrained
Better agreement during biomass burning season
1015 molec cm-2
Better spatial correlations between GOME and model NO2 columns R2 > 0.86
Space-based constraint on Space-based constraint on biomass burningbiomass burning emissions emissions
GOME NO2 regional top-down constraint of biomass burning NOx emissions
data from Martin et al. 2002
Tropics: 4.8TgN/yr 5.8TgN/yr
DJF
MAM
JJA
SON
Better spatial correlations between GOME and model HCHO columns R2> 0.7
Space-based constraint on Space-based constraint on biomass burningbiomass burning emissions emissions
data from Chance et al. 2000
Better agreement during biomass burning season
GOME HCHO top-down constraint of biomass burning VOC emissions
HCHO and alkenes emissions increased x 2GOME GEOS-Chem constrained GEOS-Chem original
Highlights of simulation evaluation: sensitivity to biomass burningHighlights of simulation evaluation: sensitivity to biomass burning
Top-down improves lower tropospheric O3 from 5-20 ppbv during biomass burning season
Main influence over Africa DJF-JJA; India MAM
Use of constrained simulation Quantify (sources/regions) influencing O3 maximum
What controls the O3 maximum?What controls the O3 maximum?
O3 maximum
?
O3 budget / Sensitivity to sourcesO3 budget / Sensitivity to sourcesSensitivity to decreasing NOx emissions by 1% and 100% for each source
ΔDU
-Lightning downwind; largest influence over the Tropics & South Atlantic
>36% >7% >9%DJF
MAM
JJA
SON
-Surface sources local; half of the lightning NOx influence (but similar source strength)
-Lightning Ozone Production Efficiency = 3 times OPE of each surface source-Tropical background 30%
O3 budget Sensitivity to regionsO3 budget Sensitivity to regions
ΔDU
Sensitivity to decreasing NOx emissions by 1% over regions
>20% >15% >6%DJF
MAM
JJA
SON
The zonal-wave oneThe zonal-wave one
Vertical-zonal seasonal cross section of O3 and O3 flux
DJF MAM
JJA SON
subsidenceAfricaS. America
Dynamical description / annual meanDynamical description / annual mean
O3 ppb NOx ppb
3/O3 buildup during transport and subsidence over South Atlantic high area
Zonal transport
1/Surface emissions of O3 precursors
S. Am. Africa
2/Injection of NOx into the MT-UT with lightning emissions and uplift into ITCZ
Modeled
SHADOZ+ MOZAIC
O3 (ppbv)
4/ Meridional transport
Meridional transport
AFRICAATLANTICS N
O3 (ppbv)
ConclusionsConclusions1/ Spatial distribution of lightning scaled to reproduce OTD-LIS seasonal mean Improve MT-UT O3 by 5 to 15 ppbv
2/ Top-down constraint on emission inventories of NOx from soil and biomass burning, of VOCs from biomass burning improve LT O3 by 5 to 20 ppbv
Lightning source of 5 Tg±2Tg best reproduces versus in-situ MOZAIC & SHADOZ
>6%
>20%
> 21% > 36%
EAST
AFRICA
South America
O3 maximum is driven by convergence and sustained largely by lightning NOx emissions, which present larger OPE
>15%
Surface NOx sources STE ~ 6%(500 Tg/yr)
Picture: METEOSAT Oct 2000
Thanks for attention!Thanks for attention!
Comparison of convective schemesComparison of convective schemes
ITCZO3 min/ CO max/ RH max
GEOS-3 presents weak convective outflow
GEOS-4 low clouds altitude & optical thickness
Weak incidence over the Atlantic
ITCZ
ITCZ
Flight altitude mean over Africa, 300-200hPa, JJA seasonCO RH
O3
CO lower estimated in LT / CO; emissions increased by 2 weak or negative impact on modeled versus in-situ
CO & Relative humidity evaluationCO & Relative humidity evaluation
Space-based constraint on emissionsSpace-based constraint on emissions
Different intensity of NOx emissions:
Biomass burning: 4.8TgN/yr 5.8TgN/yr / Soils 3.5TgN/yr 4.5TgN/yr (Tropics). Larger influence over Africa and India.
109 molec
N.cm-2.s-1
Seasonal NOx biomass burning emissions (DJF)
Original Standard