Freie Universität Berlin

Understanding past temperature changes- Update of modeling results -

Ulrike Langematz

Freie Universität Berlin

GRIPS ozone perturbation studies CCMVal ongoing activities CCMVal future plans

Freie Universität Berlin

How much of the observed stratospheric thermal and dynamical changes can be attributed to stratospheric ozone changes?

GRIPS ozone perturbation studies

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 (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

Annual and global mean temperature change due to observed O3 trend

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

GCM Ozone Perturbation Studies

SSU 1979-2003

Freie Universität BerlinFreie Universität Berlin

Shine et al., 2003

Models using Height-Resolved Observed Ozone Trends Dataset

Annual mean temperature change at 50 hPa

?

GCM Ozone Perturbation Studies

Freie Universität Berlin

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?

GCM Ozone Perturbation Studies

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

GCM Ozone Perturbation Studies

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)

GCM Ozone Perturbation Studies

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 runs using R&W and L- ozone trends (Steven Pawson) UMCAM (Peter Braesicke)

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 BerlinFreie Universität Berlin

Annual mean temperature change (K/decade)

FUB

KU NIES

WACCM MRI

GRIPS Task 3c

SSU-satellite data, 1979-03

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 Berlin

Summary

GCM ozone perturbation experiments:

- show consistent response to ozone perturbations- 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

GRIPS Task 3c

Freie Universität Berlin

Phase 1: Analysis of existing, uncoordinated CCM simulations of the period 1980-1999

different CCMs ! different experimental setups !

Validation of model results by comparison with observations

Goal: Definition of model deficits and suggestions for improvements

Quality and consistency of observational datasets?

CCMVal ongoing activities

CCMVal: CCM Validation activity for SPARC

Funded by EC-project SCOUT-O3 (Stratosphere-Climate Links With Emphasis On The UTLS)

Freie Universität Berlin

Previous CCM studies

Annual and global mean temperature change

Shine et al., 2003

Coupled chemistry models

CCMVal ongoing activities

Freie Universität Berlin

SCOUT-O3:Participating Chemistry-Climate Models (CCMs)

Acronym Resolution Experiments

EC39T30 (3.75°x3.75°)

L39 (10 hPa, 30 km)

1980-1999

(CFC, GHG, sol, volc, nud-QBO, AMIP-SST)

FUBCMAM CHEMT21 (5.6°x5.6°)

L34 (0.0068 hPa, 83 km)

1980-1999

([CFC], GHG, AMIP-SST)

MAECHAM4CHEMT30 (3.75°x3.75°)

L39 (0.01 hPa, 80 km)

1980-1999

(CFC, GHG, sol, volc, nud-QBO, AMIP-SST)

UMETRAC3.75º x 2.5º

L64 (0.01 hPa, 80 km)

1980-1999

(CFC, GHG, QBO, AMIP-SST)

UMUCAM3.75º x 2.5º

L58 (0.1 hPa, 63 km)

„1990“

(AMIP-SST)

UMSLIMCAT3.75º x 2.5º

L58 (0.1 hPa, 63 km)

1980-1999

(CFC, GHG, QBO, AMIP-SST)

SOCOL

LMD

UiO

U Aquila

Freie Universität Berlin

to do:

CCMVal ongoing activities

update Shine et al. CCM figure for CCMval models

Freie Universität Berlin

Some results from tropical analyses

CCMVal ongoing activities

Performed within SCOUT-O3 (Workpackage 1.9) at FUB

Temperature

Freie Universität Berlin

Temperature trends 1980-1999

Identical forcings in both CCMsSimilar model formulation

Top at 10 hPa (30 km)High vert. res. in UTLS

Top at 0.01 hPa (80 km)Coarser vert. Res. in UTLS

Tropopause Temperature

–

–

–

–

–

Freie Universität Berlin

Temperature trend at 70 hPa

Freie Universität Berlin

still to be done:

Global, annual mean temperature trend from CCMVal CCMs (Shine et al. 2003 figure)

CCMVal ongoing activities

appropriate observational data set ?

linear vs. multiple regression analysis ?

Freie Universität Berlin

CCMVal future plans

Coordinated reference and scenario CCM simulations for UNEP/WMO2006 Ozone Assessement

Reference simulation for 1980-2050

Identical forcings (provided on CCMVal webpage)

Analyse temperature change in these runs