Ozonkonsentrasjon som funksjon av høyde og breddegrad (jfr. Fig 10.1 i boka)

Transkript

1 Ozonkonsentrasjon som funksjon av høyde og breddegrad (jfr. Fig 10.1 i boka) Størst produksjon i øvre stratosfære i tropene Høyest konsentrasjon lavere ned ved polene Fordeling skyldes Brewer-Dobson sirkulasjon i stratosfæren

2 One DU is ozone molecules per square centimetre Eller 0.01 mm ren ozon ved STP

3 Ozonproduksjon i stratosfæren, λ < 242nm

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5 Vertikalfordeling av ozonmolekyler og atomært oksygen

6 CHAPMAN MECHANISM vs. OBSERVATION shape determined by k 1 n O2-3 Chapman mechanism reproduces shape, but is too high by factor 2-3 e missing sink!

7 Hvor høyt er blandingsforholdet av vanndamp i troposfæren?

8 Endringer i vanndamp i stratosfæren

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10 Time height plot of monthly-mean, zonalmean equatorial zonal wind (u) in m/s between about 20 and 35 km (22 mi) altitude above sea level over a ten-year period. Positive values denote westerly winds and the contour line is at 0 m/s. QBO: quasi-biennial oscillation is a quasiperiodic oscillation of the equatorial zonal wind between easterlies and westerlies in the tropical stratosphere with a mean period of 28 to 29 months.

11 NITROUS OXIDE IN THE STRATOSPHERE from CLAES satellite instrument

12 Nitrogen oxide (NO x )radicals (NO x = NO + NO 2 ) Initiation N 2 O + O( 1 D) 2NO Propagation NO + O 3 NO 2 + O 2 NO + O 3 NO 2 + O 2 NO 2 + h NO + O NO 2 + O NO + O 2 O + O 2 + M O 3 + M O 3 loss rate: Null cycle Net O 3 + O 2O 2 d[o 3] 2 k[no 2][O] dt Termination Recycling NO 2 + OH + M HNO 3 + M HNO 3 + h NO 2 + OH NO 2 + O 3 NO 3 + O 2 HNO 3 + OH NO 3 + H 2 O NO 3 + NO 2 + M N 2 O 5 + M NO 3 + h NO 2 + O N 2 O 5 + H 2 O 2HNO 3 N 2 O 5 + h NO 2 + NO 3

13 ATMOSPHERIC CYCLING OF NOx AND NOy

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16 Ozone loss catalyzed by chlorine (ClO x = Cl + ClO) radicals Initiation: Cl radical generation from non-radical precursors (e.g., CFC-12) CF 2 Cl 2 + h g CF 2 Cl + Cl λ<346 nm Propagation: Cl + O 3 g ClO + O 2 ClO + O g Cl + O 2 Net: O 3 + O g 2O 2 O 3 loss rate: d[o 3] 2 k[clo][o] dt Termination: Recycling (gas-phase): Cl + CH 4 g HCl + CH 3 HCl + OH gcl + H 2 O ClO + NO 2 + M g ClNO 3 + M ClNO 3 + h gcl + NO 3

17 Tilsvarende katalystisk ozonnebrytning med brom (Br og BrO)

18 Halogener

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20 Pyle, J. A., S. Solomon, D. Wuebbles, and S. Zvenigorodsky Ozone depletion and chlorine loading potentials. Chapter 6 in Scientific assessment of ozone depletion: World Meteorological Organization Global Ozone Research and Monitoring Project--Report no. 25. Geneva: World Meteorological Organization.

21 STRATOSPHERIC OZONE BUDGET FOR MIDLATITUDES CONSTRAINED FROM 1980s SPACE SHUTTLE OBSERVATIONS Gas-phase chemistry only

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24 ATMOSPHERIC CYCLING OF ClOx AND Cly

25 CHLORINE PARTITIONING IN STRATOSPHERE

26 Ozonhullet nå (6. september 2013)

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30 Kilde: NASA ozonewatch

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33 Perlemorskyer en form for polare stratosfæriske skyer. Ikke uvanlig over Oslo om vinteren.

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35 Trend i ozonkolonnen 60S-60N

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38 Temperaturer i stratosfæren

39 PSC-er i Antarktis 2012

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44 NASA AURA satellitten : Microwave Limb Sounder (MLS) MLS makes measurements of atmospheric composition, temperature, humidity and cloud ice that are needed to (1) track stability of the stratospheric ozone layer, (2) help improve predictions of climate change and variability, and (3) help improve understanding of global air quality. MLS observes thermal microwave emission from Earth's 'limb' (the edge of the atmosphere) viewing forward along the Aura spacecraft flight direction, scanning its view from the ground to ~90 km every ~25 seconds. Aura is in a near-polar 705 km altitude orbit. As Earth rotates underneath it, the Aura orbit stays fixed relative to the sun; to give daily global coverage with ~13 orbits per day. Aura is part of NASA's A-train group of Earth observing satellites. These satellites fly in formation with the different satellites making measurements within a short time of each other. The MLS measurements are made globally day and night. A feature of the MLS technique is that its measurements can be obtained in the presence of ice clouds and aerosol that prevent measurements by shorterwavelength infrared, visible and ultraviolet techniques.

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48 Ozon i Arktis

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50 Manney et al., Nature, 2012

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52 Hva har skjedd og hva skjer videre med utslippene? Løsningen av ozonproblemet Økt utslipp av HFC viktige drivhusgasser GWP 100 HFC-134a:1400 GWP 100 HFC-152: 124