temperature and circulation changes in the stratosphere - summary of previous workand outlook -
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Temperature and circulation changes in the stratosphere - Summary of previous workand outlook -. Ulrike Langematz. How much of the observed stratospheric thermal and dynamical changes can be attributed to stratospheric ozone changes?. Models for ozone change studies. - PowerPoint PPT PresentationTRANSCRIPT
Freie Universität Berlin
Temperature and circulation changes in the stratosphere
- Summary of previous workand outlook -
Ulrike Langematz
Freie Universität Berlin
How much of the observed stratospheric thermal and dynamical changes can be attributed to
stratospheric ozone changes?
Freie Universität Berlin
Models for ozone change studies
GCMs: Atmospheric General Circulation Models, integrated with prescribed ozone perturbations
• from observations (Langematz, 2000; Rosier and Shine, 2000; Ramaswamy and Schwarzkopf, 2003; Langematz et al., 2003)
• from offline-CTM calculations (Posters of Stolarski et al.; Schwarzkopf et al.)
GCMs with parametrized chemistry (calculated ozone change) (Rind et al., 1998; Shindell et al., 2001)
CCMs: Chemistry Climate Models with interactive chemistry modules (calculated ozone change)
(Austin, 2002; Manzini et al., 2003)
Freie Universität Berlin
GCM Ozone perturbations studies
Experimental design
20 year time slice experiments with modified O3 and CO2 in FUB-CMAM
„Change“ ≙ statistical, mean difference 2000 minus 1980
Freie Universität BerlinFreie Universität Berlin
(WMO, 1998)
Observed O3 trends 1979-1997
Ozone perturbations: Observed trends 1980-2000Constructed O3 trends for GCM
(Langematz, 2000)
annual mean
Two zonal mean ozone trend datasets available:
• Randel and Wu, 2000 • Langematz, 2000
Freie Universität Berlin
• Rosier and Shine, 2000• Langematz, 2000, Langematz et al., 2003• Ramaswamy and Schwarzkopf, 2003 Schwarzkopf and Ramaswamy, 2003
Shine et al., 2003
MA-GCM studies of the period 1980-2000 with prescribed ozone profile changes:
GCM Ozone perturbations studies I
Freie Universität Berlin
Annual and global mean temperature change due to observed O3 trend
Previous studies
Freie Universität Berlin
Shine et al., 2003
Models using Height-Resolved Observed Ozone Trends Dataset
– 1.25 to – 2.3 K/dec
– 0.25 to – 0.45 K/dec
Freie Universität BerlinFreie Universität Berlin
Shine et al., 2003
Models using Height-Resolved Observed Ozone Trends Dataset
Annual mean temperature change at 50 hPa
Previous studies
?
Freie Universität Berlin
Previous studies
GCM integrations with prescribed ozone changes
• do not reproduce the observed upper stratosphere cooling.
• do reproduce the weak middle atmosphere cooling.
• do not reproduce the lower stratosphere global mean cooling.
• do not reproduce the lower stratosphere mid-latitude cooling.
Main results
Missing processes? GHG? H2O?
Missing feedback? CCMs?
Freie Universität Berlin
Previous studies
Lower/middle stratosphere
Annual and global mean temperature change
Shine et al., 2003
Coupled chemistry models
Freie Universität Berlin
2 Goals:
Model assessment Model improvement
If model agreement Climate change assessment
GRIPS Task 3c
Coordinated GCM experiments of the period 1980-2000 with
prescribed observed ozone changes
GRIPS: GCM Realitiy Intercomparison Project for SPARC (Coordinators: Steven Pawson and Kunihiko Kodera)
Extension of Shine et al., 2003, with focus on dynamics
Freie Universität Berlin
The GRIPS 3c task
Perform two 20 year equilibrium GCM integrations• 1980 control-run • 2000 „ozone change“ run
Only difference between runs: prescribed ozone distribution for radiation code
• 1980: 1980 ozone climatology (zonal & monthly mean)• 2000: 1980 ozone climatology +observed trends 1980-2000
Ozone climatology and trends available from• Langematz (2000) • Randel and Wu (2000)
Freie Universität BerlinFreie Universität Berlin
GRIPS Task 3c
New models
CCSR/NIES AGCM • Version 5.7b • T42 L55 (0-83 km)
• O3: climatology and trends: L(2000)
WACCM • NCAR CCM3 + TIME-GCM (Sassi et al. 2002) • T63 L66 (0-140 km)
• O3: climatology and trends: R&W (2000)
Kyushu University GCM • T21L37 (0-83 km) (Miyahara et al., 1995) • O3: climatology and trends: L(2000)
MRI/JMA98 Model • T42 L45 (0-83 km) (Shibata et al., 1999) • O3: AMIP climatology, R&W (2000) trends
New in 2005:
NASA-GSFC: 2 sets of model experiments using R&W and L- ozone trendsUM model
Freie Universität BerlinFreie Universität Berlin
Annual and global mean temperature change(K/decade)
GRIPS Task 3c
WACCMNIESMRIKUFUB
altit
ude
[km
]
Freie Universität Berlin
WACCMNIESMRIKUFUB
Freie Universität Berlin
Annual and global mean temperature change(K/decade)
GRIPS Task 3c
–0.9 to –1.5 K/dec
– 0.25 to – 0.48 K/dec
altit
ude
[km
]
Freie Universität BerlinFreie Universität Berlin
Annual mean temperature change (K/decade)
SSU-satellite data, 1979-97
Scaife et al., 2000
FUB
KU NIES
WACCM MRI
GRIPS Task 3c
Freie Universität Berlin
NH summer (JJA) change, 30°N
GRIPS Task 3c
WACCMNIESMRIKUFUB
SW heating rate change [K/d/dec]Temperature [K/dec]
L-O3R&W-O3
Ozone change [%/decade]
To do: temperature change per ozone change, in progress
Freie Universität Berlin
Lower stratosphere temperature change in NH mid-latitudesK/decade
Freie Universität Berlin
FUB-analyses 1979-2000
• Models do not show uniform response. Model deficit? • No model is able to reproduce mid-latitude temperature decrease. No ozone effect!
FUB
KU NIES
WACCM MRI
GRIPS Task 3c
Freie Universität BerlinFreie Universität Berlin
NCEP-data: 1979-2000
Lower stratosphere temperature change at high latitudes(K/decade)
FUB
KU
WACCM
NIES
MRI
• Models show different cooling due to SH spring ozone depletion. Radiation code? Ozone?• No model reproduces observed NH polar spring cooling. No ozone effect.
GRIPS Task 3c
Freie Universität BerlinFreie Universität Berlin
Temperature change in DJF(K/decade)
FUB
NIESKU
WACCM MRI
GRIPS Task 3c
Freie Universität Berlin
DJF change in zonal wind, wave forcing, and residual circulation, 1980-2000
Orange (yellow): 99% (95%) stat. significance.
v* [m/s/decade]
w* [mm/s/decade]D [m/s/day/decade]
u [m/s/decade]
latitude
latitudeweaker residual circulation
stronger polarnight jet
weaker wave driving
Langematz et al., 2003
FUB-CMAM (with prescribed O3 change)
Stratospheric ozone change causes dynamical changes.
Freie Universität Berlin
Change in wave forcing in NH winter (DJF)[m/s/day/decade]
GRIPS Task 3c
FUB
KU
MRI
Freie Universität Berlin
Change in residual vertical velocity in NH winter (DJF)[mm/s/decade]
GRIPS Task 3c
FUB KU
MRI NI
Freie Universität BerlinFreie Universität Berlin
Zonal wind change in DJF(m/s/decade)
FUB
KU NIES
WACCM MRI
GRIPS Task 3c
Models do not show a consistent dynamical response.
Freie Universität BerlinFreie Universität Berlin
Change in polar vortex strength in NH spring (dam/decade)
NIES
MRI
GRIPS Task 3c
Trend 1979-2000
90‘s-70‘s(1991-2000)-(1971-1980)
FUB-data
FUB-data
FUB
March
Freie Universität Berlin
Equilibrium vs. transient response in WACCMTemperature, annual mean, [K/decade]
100hPaequilibrium
transient 100hPa
GRIPS Task 3c
Freie Universität Berlin
Summary
GCM ozone perturbation experiments:
- show global stratospheric cooling due to ozone depletion
- do not explain polar lower stratosphere cooling in NH spring
- do not explain mid-latitude cooling in lower stratosphere
No uniform dynamical signal
Work in progress
Freie Universität Berlin
More work planned in 2005
Assessment of trends in the tropical UTLS
(part of EU-SCOUT-O3 project)
Includes
trends from observations
trends from CCM simulations (with SPARC-CCMval activity)
To validate past CCM runs and coming runs with new scenarios
Work is in progress at FUB