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!
