Introduction to Environmental Earth ScienceIntroduction to Environmental Earth Science

Stratospheric Ozone DepletionStratospheric Ozone Depletion

July 24, 2007July 24, 2007

Environmental ScienceEnvironmental Science

Fumio Fumio HasebeHasebe

Stratospheric Ozone DepletionStratospheric Ozone Depletion

1.1. The Ozone LayerThe Ozone Layer

Structure of the AtmosphereStructure of the Atmosphere

Stratospheric OzoneStratospheric Ozone

Stratospheric Ozone TransportStratospheric Ozone Transport

2.2. Antarctic Ozone HoleAntarctic Ozone Hole

Mechanism of Ozone HoleMechanism of Ozone Hole

Long-term changesLong-term changes

Temperature ProfileTemperature Profile

US Standard Atmosphere

Troposphere Troposphere vs vs StratosphereStratosphere

Composite Section of Temperature & WindComposite Section of Temperature & Wind

Ozone & Temperature ProfilesOzone & Temperature Profiles

Ozone Layer

Ozone Layer

Troposphere

Troposphere

Stratosphere

Stratosphere

Absorption of Solar RadiationAbsorption of Solar Radiation

UV-B

Skin CancerSkin Cancer Terrestrial EvolutionTerrestrial Evolution

!! Outgassing Outgassing to form secondary atmosphere & oceanto form secondary atmosphere & ocean

!! Absorption of volcanic gas by the oceanAbsorption of volcanic gas by the ocean

!! Neutralization of the ocean by Neutralization of the ocean by crustal crustal metalsmetals

!! Absorption of COAbsorption of CO22 by the ocean by the ocean

!! Formation of life in the oceanFormation of life in the ocean

–– Fixing of carbon (shell --> limestone)Fixing of carbon (shell --> limestone)

–– Release of oxygen (photosynthesis)Release of oxygen (photosynthesis)

!! Formation of the ozone layerFormation of the ozone layer

–– Shield from UV-B (protection for life)Shield from UV-B (protection for life)

!! Expansion of biosphere to land surfaceExpansion of biosphere to land surface

Balance among atmosphere-ocean-biosphereBalance among atmosphere-ocean-biosphere

Positive feedbackPositive feedback

Classical TheoryClassical Theory

!! Ozone synthesis by atomic & molecular oxygenOzone synthesis by atomic & molecular oxygen

!! Energy transform from radiation to heatEnergy transform from radiation to heat

Chapman Reactions

Dominant Processes for OzoneDominant Processes for Ozone

Upper Stratosphere:

Lower Stratosphere:

Atmospheric Transport

Ozone and the General CirculationOzone and the General Circulation

Seasonal Variation of Total OzoneSeasonal Variation of Total Ozone

Min

Max

Max

Min

Ozone Destroying ReactionsOzone Destroying Reactions Ozone Destroying ReactionsOzone Destroying Reactions

Hydrogen Oxides

Nitrogen Oxides

Chlorine Oxides

Watson et al. (1986)

Anthropogenic Ozone DestructionAnthropogenic Ozone Destruction

Nature, 249, 1974

Chlorofluorocarbon (CFC)Chlorofluorocarbon (CFC)Chlorofluorocarbon (CFC)Chlorofluorocarbon (CFC)

Farman et al.(1985)

Evidence of Antarctic Ozone LossEvidence of Antarctic Ozone Loss

Total Ozone Potential Vorticity

Polar Vortex

Dynamical Field of the Ozone HoleDynamical Field of the Ozone Hole Vertical Ozone ProfilesVertical Ozone Profiles

Ozone Loss

Characteristic FeaturesCharacteristic Features

!! Ozone hole boundary corresponding to polar vortex edgeOzone hole boundary corresponding to polar vortex edge

!! ClO ClO accumulation in the vortex prior to ozone hole formationaccumulation in the vortex prior to ozone hole formation

ozone

loss

accumulation

boundary

Anderson et al. (1991)

accumulation

!! Cooling of polar night lower stratosphereCooling of polar night lower stratosphere

!! Formation of polar night jet/polar vortexFormation of polar night jet/polar vortex

!! Condensation of polar stratospheric cloud (PSC)Condensation of polar stratospheric cloud (PSC)

!! Photodissociation Photodissociation to release to release Cl Cl on sunlight returnon sunlight return

!! Chlorine-catalyzed OChlorine-catalyzed O33 destruction destruction

!! Heterogeneous reactions on the PSC surfaceHeterogeneous reactions on the PSC surface

Why So Much Why So Much ClO ClO in Ozone Hole?in Ozone Hole? Polar Ozone Depletion in SpringPolar Ozone Depletion in Spring

WMO

(2007)

Polar Ozone Depletion in SpringPolar Ozone Depletion in Spring

WMO

(2007)

Stability of the Polar VortexStability of the Polar Vortex

Yoden et al. (2002)

SummarySummary

!! Structure of the AtmosphereStructure of the Atmosphere–– Troposphere and StratosphereTroposphere and Stratosphere

–– Stratospheric Ozone LayerStratospheric Ozone Layer

!! Stratospheric OzoneStratospheric Ozone–– Absorption of Solar UV RadiationAbsorption of Solar UV Radiation

–– Protection of Life on EarthProtection of Life on Earth

–– Classical Ozone ChemistryClassical Ozone Chemistry

–– Dynamical Control in the Lower StratosphereDynamical Control in the Lower Stratosphere

!! Catalytic Ozone DestructionCatalytic Ozone Destruction–– Hydrogen, Nitrogen, Chlorine OxidesHydrogen, Nitrogen, Chlorine Oxides

–– Accumulation of Chlorine Reservoir Released from CFCAccumulation of Chlorine Reservoir Released from CFC

!! Discovery of the Antarctic Ozone HoleDiscovery of the Antarctic Ozone Hole–– Unexpected Huge Ozone Loss in the Antarctic SpringUnexpected Huge Ozone Loss in the Antarctic Spring

!! Mechanism of Ozone HoleMechanism of Ozone Hole–– Formation of PSC in the Cold Polar VortexFormation of PSC in the Cold Polar Vortex

–– Activation of Chlorine by Heterogeneous ReactionsActivation of Chlorine by Heterogeneous Reactions

!! Long-Term ChangesLong-Term Changes–– Long Lasting Monitoring is RequiredLong Lasting Monitoring is Required