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Atmospheric transport and ozone chemistry

Lecture SS 2008

Mark Weber S4350 Tel. -2362 weber@uni-bremen.de

Lecture material of today: www.iup.uni-bremen.de/~weber/vorlesung_ss08

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Introduction (today)

Atmospheric dynamics

Radiative transfer, heating, and vertical transport

Trace gases

General middle atmospheric chemistry

Ozone chemistry and catalytic cycles

Heterogeneous chemistry, stratospheric particles, and the ozone hole

The tropical tropopause

Solar (decadal) variability and dynamical coupling

Greenhouse gasses and climate-chemistry interaction

Lecture schedule

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Andrews, D. G., J. R. Holton, and C.B. Leovy, Middle Atmosphere Dynamics, Academic Press, Orlando, 1990.

Holton, J. R., An Introduction to Dynamic Meteorology, 3rd ed., Academic Press, San Diego, 1992.

Brasseur G., et al., Atmospheric Chemistry and Global Change, Oxford University Press, Oxford, 1999.

Seinfeld, J. H., Pandis, S. N., Atmospheric Chemistry and Physics – From Air Pollution to Climate Change, John Wiley & Sons, New York, 1998.

Wayne, R. P., Chemistry of Atmospheres, 3rd Ed., Clarendon Press, Oxford, 2003.

Brasseur, G., and Solomon, S., Aeronomy of the Middle Atmosphere, 3rd ed., Springer, Dordrecht, 2005.

Literature

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student presentations about WMO ozone assessment 2006

Summary of selected chapters/sections from WMO Scientific Assessment of Ozone Depletion 2006

15 minute presentations at the end of the semester

http://www.wmo.ch/web/arep/reports/ozone_2006/ozone_asst_report.html

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WMO ozone assessment and Montreal Protocol

www.iup.uni-bremen.de/~weber/WMO2006/

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WMO ozone assessment and Montreal Protocol

www.iup.uni-bremen.de/~weber/WMO2006/

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Important issues in the assessment

•ozone recovery expected from leveling off of stratospheric chlorine (Montreal Protocol and ammendments), but role of stratospheric bromine/shortlived substances may become more important

•How does climate change affect the ozone layer (Antarctic ozone hole anomaly in 2002? changes in atmpospheric transport and chemistry?)

Preface WMO O3 Assessment 2006:

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Student presentations

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student presentations about WMO ozone assessment 2006

•Select a topic or subsection until May 8 after personal consultation in my office•Presentation shall be brief, just

– summarise important findings (scientific summary in the beginnning of each chapter) supported by figures from the chapters

– discuss open scientific questions

– no more than 8-10 viewgraphs per presentations!

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IPCC Report 2007

•IPCC assessment– climate impacts from changes in greenhouse gases, note: O3 is (but a minor) greenhouse

gas– major focus: (surface) temperature, hydrological cycle (precipitation, ice sheets)

•IPCC (Intergovernmental Panel on Climate Change)•Fourth Assessment published in February 2007

http://ipcc-wg1.ucar.edu/wg1/wg1-report.html

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I.Introduction

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Climate and chemistry

Brasseur et al., 1999

Only parts are covered in this lecture

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Climate and chemistry

Brasseur et al., 1999

Only parts are covered in this lecture

Introduction:

• Stratosphere-troposphere exchange

• Distribution and variability of stratospheric ozone

• Climate change

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Troposphere-stratosphere coupling

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Stratospheric circulation and strat-trop exchange

after Holton et al. 1995

planetary wave driving by momentum and heat flux transfer from the troposhere

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Chemistry & transport of short-lived species

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Stratospheric chemistry

Brasseur et al., 1999

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Tropospheric chemistry

Up to 50% of free tropospheric ozone may be from the stratosphere Free troposphere ranges from abt. 2 km (above planetary boundary layer)

to the tropopause

Brasseur et al., 1999

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Annual cycle in total ozone

GOME / ERS II: derives total ozone columns (TOZ) from absorption signals in the backscattered UV solar radiation

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wave driventransport

Photochem. summer decay

Photochem. summer decay

ozone hole (chemical ozone loss)

Annual cycle in total ozone

Transport (dynamics) and chemistry leads to seasonal ozone variability in tropics, middle and high latitudes

Lati

tude

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The global picture: middle atmosphere dynamics

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The global picture: middle atmosphere dynamics

ozone production by photochemistry

downward transport of ozone, photochemically stable

photochemical decayozone hole, chemical

ozone loss

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Inter-annual ozone variability

63°N-90°N

63°S-90°S

Northern polar latitudes spring

Southern polar latitudes spring

‚ozone hole‘: TOZ < 200 DU

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Inter-annual ozone variability

63°N-90°N

63°S-90°S

chemical ozone loss

inter-hemispheric differences in transport

inter-annual variability in ozone chemistry & transportin each hemisphere

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Ozone hole and polar vortex, southern hemisphere

GOME total ozone above Antarctica 1996-2002 Low inter-annual ozone variability in SH winter/spring

cold Antarctic stratospheric winters with low ozone („hole“) and large polar vortex every year

exception 2002, rather warm with higher ozone, but 2003 and 2004 are cold again like before (not shown)

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Ozone hole and polar vortex, southern hemisphere

GOME/SCIAMACHY October total ozone above Antarctica 1996-2006 Low inter-annual ozone variability in SH winter/spring

cold Antarctic stratospheric winters with low ozone („hole“) and large polar vortex every year

exception 2002, rather warm with higher ozone.

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Ozone variability in northern hemisphere

63°N-90°N

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Ozone variability

High inter-annual ozone variability in winter/spring NHCold (stratospheric) Arctic winters with low ozone:

1996, 1997, 2000, (2003), 2005Warm Arctic winters with high ozone

1998, 1999, 2001, 2002, 2004

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Polar stratospheric temperature anomalies

Correlation of stratospheric temperatures and polar ozone, e.g. low temperatures and low ozone

analysis datasatellite dataradiosondes

Note: here are anomalies shown (differences to long-term mean)

Polar stratospheric T are lower in SH winter than in NH winter (about 15 K)

50 hPa/ ca. 18 km altitude

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15-23 km8-15 km 23-30 km

Ozone minihole„dynamics“

ozone inside polar vortex„dynamics and chemistry“

Eichmann et al. 1999

Height resolved ozone from GOME

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Transport and changes in chemical composition

Transport and chemical composition: subtropical streamer (high tropopause) in NH mid latitudes

low ozone above Europe (mini-hole)

Geopotential height in dekameter at 300 hPa (ca. 9 km altitude)

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Tropospheric weather patterns and stratospheric ozone

North Atlantic Oscillation (NAO) is the normalised (surface) pressure difference between Lisbon (Portugal) and Stykkisholmur (Island) for the winter months December-March

Connection between tropospheric weather patterns (surface) and stratospheric ozone (~22 km altitude)

90% of ozone in stratosphere total ozone mainly stratospheric ozone

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Climate change: evolution of greenhouse gases

Note today:

[CO2] 380 ppmv

[CH4] 1700 ppbv

IPCC 2001

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Climate change: evolution of greenhouse gases

Note today:

[CO2] 380 ppmv

[CH4] 1700 ppbv

Mouna Loa Hawaii

Ahrens 1999

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Climate change: evolution of greenhouse gases

Note today:

[CO2] 380 ppmv

[CH4] 1700 ppbv

Buchwitz et al., 2007

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Can we learn from the past?

Note today:

[CO2] 380 ppmv

[CH4] 1700 ppbv

Age in kyears

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Surface temperature from the past to the future

Mann et al, 1998

Mann et al., 1998: temperature proxy dataECHO-G1: climate model result

Cubash

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Relationship between climate elements

energy budget

temperature

wind, cloud, precipitation,atmospheric waves &

circulation

atm

os

ph

ere

solar radiationheat flux from

ocean

topography,

geography

soil composition,

vegetation, albedo

human activities, natural emission,volcanism

Impact ontrace gaseschemistrytransport

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Atmospheric scales

turbulence, lightning, tornadoes

< 100 kmmicro

mountain winds, foehn, hurricanes

~100 kmregional

sea wind circulation, frontal systems,gravity waves

<1000 kmmesoscale

cyclonic wavesplanetary waves

global, > 1000kmSynoptic

phenomenasscaleterminology

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Atmospheric scales

turbulence, lightning, tornadoes

< 100 kmmicro

mountain winds, foehn, hurricanes

~100 kmregional

sea wind circulation, frontal systems,gravity waves

<1000 kmmesoscale

cyclonic wavesplanetary waves

global, > 1000kmSynoptic

phenomenasscaleterminology

troposphere

stratosphere

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Atmospheric space and time scales

Glossary: planetarische Wellen=planetary scale waves, Wolken Cluster=cloud cluster, kleinräumige Turbulenz= small scale turbulence, Schwerewellen=gravity waves, Schallwellen=sound waves, kleinräumig=micro scale, grossräumig=synoptic

tim

e s

cale

spatial scale

Warn

eke 1

99

7

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Chemical time scales

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Chemical composition and global change

What causes the large chemical ozone depletion in SH spring?

High stratospheric chlorine (halogen) loading from CFC emissions

Cold temperatures inside the polar vortex

However, past and future stratospheric temperatures depend on climate changes

Globalwarming

emissions

deforrestation

pytoplanctondestruction

troposphericozone formation

stratospheric ozone depletion

modification of tropospheric chemistry

CFCs

equivalent effective stratospheric chlorine

(EESC)