simulating the atmospheric composition during the last decades: evaluation with long-term...
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Simulating the atmospheric composition during the last decades: Evaluation with long-term observational datasets and the impact of natural climate variabilityVolker Grewe, Martin Dameris, Jens Grenzhäuser
and Pieter ValksGerman Aerospace Center
ACCENT-GLOREAM, Paris, October, 2006
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Physik der Atmosphäre
Transport and Chemistry
NOx - Ozon Production
Ozone Production
(Chapman)Ozone Intrusion
ENSO
Solar Cycle
Air Quality
Emissions
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Physik der Atmosphäre
CCM E39/C (Stratosphere-troposphere)- Model description
Surface, aircraft, lightning
NOx Emissions [Tg N/a]
RadiationLong-waveShort-wave
Chemical Boundary Conditions
Atmosphere: CFCs, at 10 hPa: ClX, NOy,
Surface: CH4, CO
Chemistry (CHEM)Methane oxidationHeterogeneous Cl
reactionsPSC I, II, aerosolsDry/wet deposition
Photolysis
Feedback
O 3, H
2O, C
H 4, N
2O,
CFCs
Prognostic variables (vorticity, divergence, temperature, specific humidity, log-surface pressure, cloud water),
hydrological cycle, diffusion, gravity wave drag, transport of tracers,
soil model, boundary layer;sea surface temperatures.
T30, 39 layers, top layer centred at 10 hPaDynamics (ECHAM)
Hein et al., 2001
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Institutstag IPA 2006
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Physik der Atmosphäre
Transiente Model simulation - Boundary ConditionsQBO
Solar cycle and volcanoes
Dameris et al., 2005
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Physik der Atmosphäre
Transiente Model simulation - Boundary Conditions
Natural und anthropogenic NOx emissions:Source Reference Emissions: 1960 to 2000
Industry Benkovitz et al., 1996 12 - 33 TgN/aLightning Grewe et al., 2001 ~5 TgN/aAir traffic Schmitt und Brunner, 97 0.1 - 0.7 TgN/aSurface Traffic Matthes, 2003 3.6 - 9.9 TgN/aShips Corbett et al, 1999 1.2 - 3.2 TgN/a Biomass Burning Lee, pers. comm 6.3 - 7.2 TgN/a
Sea surface temperatures andice coverage:
Monthly means: UK Met Office Hadley Centre, hier: Beispiel für Juni 1985 (Rayner et al., 2003)
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Evolution of ozone column [DU]: 1960 - 2000
1960
2000
1980
1980
Ozone hole
Highvariability
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De-seasonalized anomalies of the ozone columns [%]
+ + + ++ - - --
QBO clearly visible
Global Trend:~20 DU
1960
2000
1980
1980
11y- Solar cycle recognizable, but
QBO, volcanoes, trendoverlaid
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2006
Institutstag IPA 2006
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E39/C vs. Observation: Anomalies of ozone column
E39/C
TOMS
Groundstations
(Bojkov and Fioletov, 1995; pers. com. Fioletov, 2004)
calm, stable winter situations
Beginning of 90s:
stronger ozone losses
Individual strong events
well represented
Institut für Physik der Atmosphäre
Validation of E39C results: Tropospheric Ozone
Mean annual cycle of ozone at 47°N, 11°E (1967-2000)
E39C
OBS
E39C minus OBS
Hohenpeißenberg
Too weak seasonal cycle
Cold bias too = high tropopause
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Validation of E39C results
Mean annual cycle of ozone at 40°N, 105°W (1979-2000)
E39C
OBS
E39C minus OBS
Boulder
Similar conclusion
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Validation of E39C results
47°N, 11°E; 300 hPa
47°N, 11°E; 500 hPa
47°N, 11°E; 700 hPa
47°N, 11°E; 850 hPa
OzonesondeE39C
OzonesondeE39C
OzonesondeE39C
OzonesondeE39C
Evolution of ozone anomalies at distinct levels [in ppbv] Hohenpeißenberg
Variability smaller: Sampling or real difference ?
Evolution not well reproduced: - very rough assumptions on emission data - no interannual variability of bb emissions
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Validation of E39C results
47°N, 11°E; 500 hPa
OzonesondeE39C
Evolution of ozone anomalies [in ppbv]
Some agreement:Coincidience orperiod where changes are controll by processes,which are better described
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Average tropospheric tropiocal O3-Column below 200 hPa 1996-2003
Generally higher ozone values !
General pattern in agreement:Minimum over PacificMaximum over Africa
GOME (TEMIS) E39/C
However, ozone maximum less pronounced:Biomass burning?
180°W
20°N
Eq.
180°E20°S
MAM
DJF
JJA
SON
15-40 DU 10-30 DU
Minimum South America
Maximum Africa
Minimum Pacific
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How can we understand the simulated trends and the observed differences ?
- Sensitivity studies (for selected periods)
e.g. rerun period without volcanic eruption (Pinatubo)
- Additional diagnostics
Tracer: Ozone origin (Regions in Stratosphere/ Troposphere)
Tracer: Ozone 'source') (biomass burning, Lightning, ...)
Mass fluxes
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Physik der Atmosphäre
Simulated ozone origin
Grewe, 2006
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Physik der Atmosphäre
Grewe, 2004
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Institutstag IPA 2006
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Physik der Atmosphäre
Ozone influx from the stratosphere to the troposphere
De-seasonalized
Monthly means
x
Estimate based on correlations with long-lived species: 475 Tg/year
(Murphey and Fahey, 1994) and with flux calculations:
NH: 252 Tg/a SH: 248 Tg/a(Olson et al., 2004)
Signal of solar cycleidentifyable
especially on SH
Large interannualvariability
No trends recognizable
+ - + - + - + - +
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2006
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Physik der Atmosphäre
De-seasonalized ozone changes in the tropical UT
Stratospheric ozone follows
influx from stratosphere, producing
±2% variability out of a
totale interannual var. of ±4%
Lightning ozone
correlated with Nino Index
variability: ±1-2%
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03.
2006
Institutstag IPA 2006
Institut für
Physik der Atmosphäre
Evolution of de-seasonalized ozone in NH lower troposphere (30N-90N; 500-1000 hPa)
Year-to-year variability strongly dominated by stratosphere (±5%) Trend in ozone (25% increase):- results from increase in NOx emissions (Industry and traffic)
- Trend reduction in 80s caused by lower emissions and lower stratospheric contribution.
~25%
~30%
-5%
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Conclusions - Outlook (I) Stratosphere well reproduced
Troposphere: Some similarities with observational data
Main Discrepancies: Too weak seasonal cycle:
- Too strong influence from stratosphere (chem lifetime)- Too much transport of upper troposphere tropical air- Too weak seasonal cycle of O3 perturbation
from anthropogenic emissions Less intense tropical ozone maximum
Solution: Rerun with revised emission data (RETRO)biomass burning + anthrop. emission dataincluding interannual and regional variability
Institut für Physik der Atmosphäre
Conclusions - Outlook (II)
Discrepancies: Less ozone in the upper troposphere:
- Problem of cold bias = too high tropopauseSolution: Lagrangian transport scheme
→ Realistic water vapor transport → 80% Reduction of Cold Bias (Stenke&Grewe, 2006)
Despite discrepancies Stratospheric ozone variability influences trend
(Trend reduction in 80s) Impact of stratospheric and tropospheric variability
(El Nino) quantified.
Institut für
Physik der Atmosphäre