Langematz u 20150707_1700_upmc_jussieu_-_amphi_astier

Future stratospheric ozone

in a changing climate

Ulrike Langematz,

Stefanie Meul, Erik Romanowsky, Anne Kubin,

Janna Abalichin, Sophie Oberländer-Hayn

2

from CCMVal2 Chemistry-Climate Model projections

Annual global mean total ozone 1960-2100

Ulrike Langematz, CFCC15, Paris, 7 July 2015

3

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


4

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?


5

Tropical ozone

Ozone Cly at 50 hPa

Will future tropical ozone recover, and how is it affected by

climate change?


6

• 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


7

• 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


8

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


9

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


10

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


11

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


12

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-


13

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


14

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


15

What is the effect on Arctic total ozone?

VPSC

Rex et al., 2006

Maximum VPSC with

climate change during

1st half of 21st century


16

RE

F

Arctic total ozone in March

CFC⇗ CFC⇘

GHG ⇧

2017


17

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.


18

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. ……”


19

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


20

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

Langematz u 20150707_1700_upmc_jussieu_-_amphi_astier

Science

Transcript of Langematz u 20150707_1700_upmc_jussieu_-_amphi_astier