langematz u 20150707_1700_upmc_jussieu_-_amphi_astier
TRANSCRIPT
Future stratospheric ozone
in a changing climate
Ulrike Langematz,
Stefanie Meul, Erik Romanowsky, Anne Kubin,
Janna Abalichin, Sophie Oberländer-Hayn
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from CCMVal2 Chemistry-Climate Model projections
Annual global mean total ozone 1960-2100
Ulrike Langematz, CFCC15, Paris, 7 July 2015
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Arctic (March) 2026 (2023-2031)
Antarctica (October) 2051 (2046-2057)
NH mid-latitudes 2021 (2017-2026)
Expected return of total ozone to 1980 levels
Polar spring ozone
Ulrike Langematz, CFCC15, Paris, 7 July 2015
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courtesy Mark Weber, Uni Bremen
Gome-2
Total Ozone
Arctic Ozone 2011
• Unprecedented Arctic ozone loss in
March 2011
• Comparable to Antarctic ozone hole
• Due to
• persistent cold lower stratosphere
from early winter into spring
- early onset of denitrification
- long-lasting chlorine activation
• large VPSC
e.g., Manney et al., 2011
Is there a risk that extreme Arctic ‚ozone-hole-like‘ events will
become more frequent in a future with climate change?
Ulrike Langematz, CFCC15, Paris, 7 July 2015
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Tropical ozone
Ozone Cly at 50 hPa
Will future tropical ozone recover, and how is it affected by
climate change?
Ulrike Langematz, CFCC15, Paris, 7 July 2015
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• ECHAM/MESSy Atmospheric Chemistry model (EMAC) (Jöckel et al., 2006)
• ECHAM5 atmospheric model (Röckner et al., 2006)
• Interactive chemistry model MECCA (Sander et al., 2005)
• Improved shortwave radiation scheme FUBRad (Kunze et al., 2012)
• Resolution: T42 (2.8°x2.8°), L39 or L47 or L90 (top at 0.01 hPa, 80 km)
The Model
• Transient, 1960-2100,
• ODSs: Obs + A1WMO (2007),
• GHGs: SRES A1b, RCP 4.5, RCP 6.0, RCP 8.5
• Time slices (> 40 years)
• 1865, 1960, 2000, 2045, 2095
• Different individual and combined ODS and GHG forcings
Simulations
Ulrike Langematz, CFCC15, Paris, 7 July 2015
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• What is the effect of increasing GHG concentrations on the
Arctic polar lower stratosphere?
• How will the meteorological conditions in the Arctic lower
stratosphere change with rising GHGs?
• How will they affect ozone?
Radiative cooling More PSCs More ozone loss
Less ozone loss Dynamical forcing Arctic warming
or ?
Arctic ozone
Ulrike Langematz, CFCC15, Paris, 7 July 2015
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1960-2099, K/decade
March
Stratospheric cooling due to GHG increases?
• Cooling in early winter, but no significant change in mid-winter and spring
• Cooling due to GHG increase
January/February November/December
Langematz et al., JGR, 2014
Ulrike Langematz, CFCC15, Paris, 7 July 2015
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Arctic minimum temperatures
+0.13 ± 0.06K/dec
• Significant future decrease in Arctic minimum temperature only in early
winter
REF, November/December
-0.18 ± 0.03 K/dec
REF, March
TNAT TNAT
Ulrike Langematz, CFCC15, Paris, 7 July 2015
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Seasonal evolution of Arctic minimum temperatures
multiyear mean Tmin north of 40°N
ODSs led to
lower Tmin in late
winter.
Future increased
GHGs will lead to
lower Tmin in early
winter.
lower stratosphere
Ulrike Langematz, CFCC15, Paris, 7 July 2015
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Arctic polar vortex persistence Zonal wind transition, 65°N, 50 hPa
summer ➙ winter winter ➙ summer
• No effect of ozone depletion/recovery on Arctic vortex spring persistence
• Enhanced future Arctic vortex duration due to earlier build-up in autumn due to GHGs
Ulrike Langematz, CFCC15, Paris, 7 July 2015
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Dynamical forcing of the stratosphere 100 hPa eddy heat flux
2000
2095
2045 Enhanced planetary
wave forcing from
troposphere in mid-
winter due to GHG
increase-
Ulrike Langematz, CFCC15, Paris, 7 July 2015
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Potential PSC area with T < TNAT 50 hPa, 40°-90°N
Enhanced PSC formation potential in early winter due to GHGs
2045
2000
1865 2095
Ulrike Langematz, CFCC15, Paris, 7 July 2015
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Accumulated potential PSC area fraction 50 hPa, 40°-90°N
Strong increase by ODS in late winter
Strong increase by GHG in early winter
Maximum accumulated VPSC in 2045
Ulrike Langematz, CFCC15, Paris, 7 July 2015
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What is the effect on Arctic total ozone?
VPSC
Rex et al., 2006
Maximum VPSC with
climate change during
1st half of 21st century
Ulrike Langematz, CFCC15, Paris, 7 July 2015
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RE
F
Arctic total ozone in March
CFC⇗ CFC⇘
GHG ⇧
2017
Ulrike Langematz, CFCC15, Paris, 7 July 2015
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Tropical ozone
Meul et al., ACP, 2014
Projected change in annual mean ozone from 2000 to 2095
Tropical ozone loss in lower stratosphere due to transport by enhanced tropical
upwelling and subsequent changes in ozone production and destruction.
Ulrike Langematz, CFCC15, Paris, 7 July 2015
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WMO 2014: Tropical ozone
Figure ADM 3-3,
Scientific Assessment of ozone
depletion: 2014, WMO
“The projected future evolution of tropical total column ozone is strongly dependent
on future abundances of CO2, N2O, and CH4 (e.g., as in Representative
Concentration Pathways (RCPs)), and is particularly sensitive to changes in the
tropical upwelling and changes in tropospheric ozone. ……”
Ulrike Langematz, CFCC15, Paris, 7 July 2015
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Tropical ozone in EMAC-CCM
Meul et al., to be submitted, 2015
Tota
l colu
mn
U
ppe
r str
ato
sphere
Low
er
str
ato
sphere
T
roposp
here
ODS decline
GHG cooling CH4 increase in
RCP8.5
BDC increase
RCP 4.5 RCP 6.0 RCP 8.5
Ulrike Langematz, CFCC15, Paris, 7 July 2015
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Conclusions
Funded by DFG
• Future global and polar ozone will recover to 1980 values due to the
decline of ODSs as a result of the Montreal protocol.
• However, the future evolution of stratospheric ozone is considerably
affected by climate change:
Arctic:
• GHG induced cooling of the Arctic early winter stratosphere enhances the
probability of PSC formation and ozone loss until the middle of the 21st century.
Stronger wave forcing compensates radiative cooling in Arctic spring.
• No tendency to future Arctic ozone holes, but individual events seem possible.
Tropics:
• Future tropical ozone will not recover in the lower stratosphere due to an
increase of the BDC, modified by changes in ozone chemistry.
• Future evolution of tropical ozone strongly depends on future GHG abundances
(CO2, CH4, and N2O).
Thank you! Ulrike Langematz, CFCC15, Paris, 7 July 2015