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Understanding past temperature changes - Update of modeling results -. Ulrike Langematz. GRIPS ozone perturbation studies CCMVal ongoing activities CCMVal future plans. GRIPS ozone perturbation studies.

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slide1

Understanding past temperature changes

- Update of modeling results -

Ulrike Langematz

slide2

GRIPS ozone perturbation studies

  • CCMVal ongoing activities
  • CCMVal future plans
slide3

GRIPS ozone perturbation studies

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

slide4

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, ….)

slide5

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

slide6

Constructed O3 trends for GCM

annual mean

(Langematz, 2000)

Two zonal mean ozone trend datasets available:

• Randel and Wu, 2000

• Langematz, 2000

Freie Universität Berlin

Ozone perturbations: Observed trends 1980-2000

Observed O3 trends 1979-1997

(WMO, 1998)

slide7

GCM Ozone Perturbation Studies

Freie Universität Berlin

Annual and global mean temperature change due to observed O3 trend

Models using Height-Resolved Observed Ozone Trends Dataset

SSU 1979-2003

– 1.25 to – 2.3 K/dec

– 0.25 to – 0.45 K/dec

Shine et al., 2003

slide8

GCM Ozone Perturbation Studies

?

Freie Universität Berlin

Annual mean temperature change at 50 hPa

Models using Height-Resolved Observed Ozone Trends Dataset

Shine et al., 2003

slide9

GCM Ozone Perturbation Studies

Main results

  • 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.

Missing processes? GHG? H2O?

Missing feedback?  CCMs?

slide10

GCM Ozone Perturbation Studies

  • 2Goals:
    • Model assessment Model improvement
    • If model agreement Climate change assessment

GRIPS Task 3c

  • GRIPS: GCM Realitiy Intercomparison Project for SPARC

(Coordinators: Steven Pawson and Kunihiko Kodera)

  • Coordinated GCM experiments of the period 1980-2000

with prescribed observed ozone changes

  • Extension of Shine et al., 2003, with focus on dynamics
slide11

GCM Ozone Perturbation Studies

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)
slide12

GRIPS Task 3c

Freie Universität Berlin

New models

  • Kyushu University GCM • T21L37 (0-83 km)

(Miyahara et al., 1995) • O3: climatology and trends: L(2000)

  • 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)

  • 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)
slide13

GRIPS Task 3c

WACCM

NIES

MRI

KU

FUB

Freie Universität Berlin

Annual and global mean temperature change

(K/decade)

–0.9 to –1.5 K/dec

altitude [km]

– 0.25 to – 0.48 K/dec

slide14

GRIPS Task 3c

KU

NIES

SSU-satellite data, 1979-97

Scaife et al., 2000

WACCM

MRI

Freie Universität Berlin

Annual mean temperature change(K/decade)

FUB

slide15

GRIPS Task 3c

KU

NIES

SSU-satellite data, 1979-03

WACCM

MRI

Freie Universität Berlin

Annual mean temperature change(K/decade)

FUB

slide16

GRIPS Task 3c

KU

NIES

FUB-analyses 1979-2000

FUB

WACCM

MRI

Freie Universität Berlin

Lower stratosphere temperature change in NH mid-latitudes

K/decade

  • Models do not show uniform response.  Model deficit?
  • No model is able to reproduce mid-latitude temperature decrease.  No ozone effect!
slide17

GRIPS Task 3c

KU

NIES

NCEP-data: 1979-2000

FUB

WACCM

MRI

Freie Universität Berlin

Lower stratosphere temperature change at high latitudes

(K/decade)

  • Models show different cooling due to SH spring ozone depletion.  Radiation code? Ozone?
  • No model reproduces observed NH polar spring cooling.  No ozone effect.
slide18

GRIPS Task 3c

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
slide19

CCMVal ongoing activities

  • CCMVal: CCM Validation activity for SPARC
  • 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
  • Quality and consistency of observational datasets?
  • Goal: Definition of model deficits and suggestions for

improvements

  • Funded by EC-project SCOUT-O3 (Stratosphere-Climate Links

With Emphasis On The UTLS)

slide20

CCMVal ongoing activities

Coupled chemistry models

Shine et al., 2003

  • Previous CCM studies

Annual and global mean temperature change

slide22

CCMVal ongoing activities

to do:

update Shine et al. CCM figure for

CCMval models

slide23

CCMVal ongoing activities

  • Some results from tropical analyses
  • Performed within SCOUT-O3 (Workpackage 1.9) at FUB
slide25

Temperature trends 1980-1999

Identical forcings in both CCMs

Similar 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

slide26

Tropopause Temperature

slide28

CCMVal ongoing activities

  • still to be done:

Global, annual mean temperature trend from CCMVal

CCMs (Shine et al. 2003 figure)

  • appropriate observational data set ?
  • linear vs. multiple regression analysis ?
slide29

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
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