Volker Grewe, Martin Dameris, Jens Grenzhäuser and Pieter Valks German Aerospace Center

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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2006

Institutstag IPA 2006

Institut für

Physik der Atmosphäre

Transport and Chemistry

NOx - Ozon Production

Ozone Production

(Chapman)Ozone Intrusion

ENSO

Solar Cycle

Air Quality

Emissions

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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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Transiente Model simulation - Boundary ConditionsQBO

Solar cycle and volcanoes

Dameris et al., 2005

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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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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


Validation of E39C results

Mean annual cycle of ozone at 40°N, 105°W (1979-2000)

E39C

OBS

E39C minus OBS

Boulder

Similar conclusion



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



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


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


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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Simulated ozone origin

Grewe, 2006

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Grewe, 2004

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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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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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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%


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


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


Volker Grewe, Martin Dameris, Jens Grenzhäuser and Pieter Valks German Aerospace Center

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