the origin of stratospheric ozone in sensitivity studies with emac-fub

The origin of stratospheric ozone in sensitivity studies with EMAC-FUB

EGU – European Geosciences Union General Assembly 2011

Vienna

S. Meul1), S. Oberländer1), A. Kerschbaumer1), U. Langematz1), V. Grewe2)

1) FU Berlin 2) DLR, Oberpfaffenhofen

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Motivation

The ozone distribution is determined by local production, loss and transport

Analyses of the present-day chemical and dynamical mechanisms

Information of the O3 origin offer a new approach for studying the transport patterns and the chemistry

Study of the ‚drivers‘ of future ozone changes in the stratosphere

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Model setup

- version 1.7- horizontal resolution: 2.8°x2.8° (T42)

- vertical resolution: 39 levels (model top: 0.01 hPa)

- shortwave radiation parameterisation: FUBRad (EMAC-FUB) (Nissen et al., 2007)

- prescribed sea-surface-temperatures (SSTs) and sea-ice- concentrations (SIC) (modelled, MPI-OM)

- ozone origin diagnostic (Grewe, 2006)

• Chemistry-Climate Model ECHAM5/MESSy Atmospheric Chemistry

(EMAC) (Jöckel et al., 2006):

• Time-slice experiment (20 years) for the year 2000 (GHGs, ODSs, mean SSTs/SICs of the period 1995-2004, solar mean)

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This diagnostic tool allows the identification of the ozone origin at each grid point in the atmosphere (at each timestep)

• Method:

1. Definition of n ozone production (= origin) regions in the model domain (n=19)

tropopause

Ozone production regions

1000

10

1

0.03

Pre

ssu

re [

hP

a]

60°N60°S

lower mesosphere (LM)

upper stratosphere (US)

middle stratosphere (MS)

Method: The ozone origin diagnostic (V. Grewe, 2006; Garny et al., 2011 (submitted))

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Method: The ozone origin diagnostic (V. Grewe, 2006; Garny et al., 2011 (submitted))

This diagnostic tool allows the identification of the ozone origin at each grid point in the atmosphere (at each timestep)

• Method:

2. Implementation of an ozone tracer o3i for each region i (i=1,n)

) transported destroyed(destroyed

ozone is produced in region i marked with i (o3i)

production of o3i outside region i = 0 and

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January

[%]

Method: The ozone origin diagnostic

Contribution of the ozone origin tracer o3i to the full ozone field O3

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1. Part: Ozone budgets

- tropical lower stratosphere- northern polar middle stratosphere

Monthly ozone budget of the tropical lower stratosphere

• positive net production

• negative transport → ‚export‘

• O3 increase Feb-Aug: net production > export

• O3 decrease Oct-Jan: net production < export

transport = tendency – (production – loss)

net production

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μm

ol m

ol-1

mo

nth

-1

box-weighted mean

Monthly ozone budget of the northern polar middle stratosphere

• negative net production

• positive transport → ‚import‘

• O3 increase Sep-Mar: loss < import

• O3 decrease Apr-Aug: loss > import

transport = tendency – net production

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μm

ol m

ol-1

mo

nth

-1

box-weighted mean

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2. Part: The origin of ozone

- northern middle stratosphere- comparison of the polar middle

stratosphere in the NH and SH

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The origin of northern middle stratospheric ozone

O3 (black) and o3i

Polar Region (60°-90°N)Mid-latitudes (20°-60°N)

pp

mv

locally produced

Seasonal cycle of O3 driven by the locally produced ozone

Seasonal cycle of O3 as a combination of locally produced and ‚transported‘ ozone

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o3i /O3*100%

Polar Region (60°-90°N)

Sum of o3i minus locally produced O3

Mid-latitudes (20°-60°N)

The origin of northern middle stratospheric ozone

July: (70%) NMUS (23%) NPMS (3%)

January: (58%) NMUS (24%) TRMS (8%)

July: (67%) NPUS (20%) NMMS (12%)

January: NMMS (53%) NMUS (29%)

(8%)

%

winter: - larger abundance of mid-lat originating O3 in the NH - larger abundance of

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SH Polar Region (60°-90°S) NH Polar Region (60°-90°N)

pp

mv

Jan

winter: larger abundance of upper stratospheric polar O3 in SH

locally produced

Jul

Ozone hole

The origin of polar middle stratospheric ozone

stronger downward motion inside the vortexSH polar vortex edge less

permeable for meridional O3 transport + weaker meridional circulation

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Summary & Outlook- Analyses of the ozone budget and ozone origin in the present- day time-slice simulation with the CCM EMAC-FUB

- Studies of future changes in ozone transport and chemistry by comparing different sensitivity experiments

Future (2045) – Reference (2000)(annual mean)

ΔO

3 in

pp

bv/

dec

ade

Thank you!