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Tropospheric Circulation Changes in Response to a
Stratospheric Zonal Ozone Anomaly - Model Results
Dieter H.W. Peters, A. Schneidereit, Ch. Zülicke, I. Kirchner*
Leibniz IAP, Kühlungsborn, U Rostock
* Institute of Meteorology, FU Berlin
Predictability ANd Dynamics
Of Weather Systems
in the Atlantic-European Sector
VARNAER
is a DFG funded project
in the frame of
the PANDOWAE group
www.pandowae.de
SNAP-Reading-25.4.2013
European
Windstorms
Severe
Convection
Mediterranean
Cyclones
Tropical
Cyclones
PANDOWAE
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Outline
- Motivation
=>
open questions
- Methodology =>+ perform two 40-year runs with ECHAM5-MA,
forced with AMIP SSTs, from 1960-1999,
+ further diagnosis of
quasi-stationary waves,
SSW events, NAM variance,
predictability : NAM(p) => AO,
poleward RWB events of typ P2
- Model results=> for control run with ZSO3 (O3SYM)
for anomaly run with both ZSO3+ASO3* (O3ASYM)
- Summary
SNAP-Reading-25.4.2013
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Motivation
Open questions:
• Which surface and tropospheric influences are induced by
the zonally asymmetric ozone in the stratosphere?
+ showing results for a sensitivity study, extension of
former similar studies (Kirchner & Peters, 2002; …)
• How does zonally asymmetric ozone change the dynamical
coupling of atmospheric layers?
+ discussion of mechanism
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Sensitivity study with ECHAM5
-
Methods I
Model configuration:
+ performed two AGCM - ECHAM5-MA runs (for T42, L39, Htop  80km)
(Roeckner et al. 2002, Manzini et al. 2006)
+ runtime interval is 40 years forced with same AMIP SST from 1960 until 1999
but different ozone fields are used:
- O3SYM: control run with mean zonally symmetric ozone of the 1990s
- O3ASYM: anomaly run with added zonally asymmetric ozone O3* field
based on ERA-40 ozone fields of the 1960 – 1999 period
including months to months and inter-annual variability
Remarks:
+ implemented O3* field only north of 30° N and between 500 and 1 hPa layer
+ no trend in zonally symmetric ozone field was considered
+ due to fixed O3* field any transport of ozone was excluded
+ aim is to isolate the heating effects of zonally asymmetric ozone
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Structure evolution of decadal zonally asymmetric O3*
Mean O3* at 20 hPa
1990s
1960s
+ wave-1 structure in zonally asymmetric ozone
+ increase and decadal variability in ozone amplitude
SNAP-Reading-25.4.2013
ERA-40
Winter (DJF)
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Quasi-stationary wave change for January – Result I
Difference O3ASYM – O3SYM
+ westward shift of the vortex by about 60 degree
+ significant (95 %) in the middle and lower
stratosphere for O3* anomaly run in January
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Sensitivity study with ECHAM5 – SSW – Result II
+ number of major SSW events without final
O3SYM
O3ASYM
+ significant increase of major SSW events in 1980/90s for O3ASYM run
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Mean inter-annual NAM variance – Result III
O3SYM control run
O3ASYM anomaly run
ERA-INTERIM
+ comparable low-pass variance structure in
ECHAM5 model runs and ERA-Interim
+ significant change (green line, 95 % conf.) in
the upper stratosphere for O3* anomaly run
SNAP-Reading-25.4.2013
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Prediction of AO by NAM (p) – Result IV
+ less NAM predictability in model runs in comparison to ERA INTERIM reanalysis
+ improvement of predictability by zonally asymmetric ozone O3* (anomaly run) in the
middle stratosphere
+ significant increase in early winter and midwinter as known from observation
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Sensitivity study with ECHAM5 – AO – Result V
ERA-Interim
O3SYM
O3ASYM
+ AO+ minimum in mid-1980s, followed by an increase for O3ASYM run
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Sensitivity study with ECHAM5
RWB –P2
+ anticyclonic Rossby wave breaking of poleward type P2
difference
O3SYM
for mean winter (DJF) O3ASYM
+ significant change of P2-RWB events over western Europe in O3ASYM during
1980-1999 period due to stronger diffluence of the background field
+ explanation was given by Peters & Waugh (1995 JAS)
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Summary & conclusion
- model study
+ found significant changes of stationary wave, of intra-seasonal and
interannual variability in the stratosphere which are induced by
zonally asymmetric ozone in the stratosphere
+ further: showed a significant increase of the predictability of surface
AO by NAM (p) in midwinter
+ furthermore: identified significant more poleward Rossby wave
breaking events over the NA-EU-region in upper troposphere
+ conclude that zonally asymmetric ozone heating caused a significant
change in the stratospheric and tropospheric circulation, especially it
changed the structure of RWB events over the NA-EU region
+ zonally asymmetric ozone should be considered in the CMIP6
SNAP-Reading-25.4.2013
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© dhwpe
Thanks for attention!