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Understanding past temperature changes - Update of modeling results -

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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Understanding past temperature changes - Update of modeling results -

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  1. Understanding past temperature changes - Update of modeling results - Ulrike Langematz

  2. GRIPS ozone perturbation studies • CCMVal ongoing activities • CCMVal future plans

  3. GRIPS ozone perturbation studies How much of the observed stratospheric thermal and dynamical changes can be attributed to stratospheric ozone changes?

  4. 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, ….)

  5. 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

  6. 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)

  7. 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

  8. 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

  9. 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?

  10. 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

  11. 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)

  12. 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)

  13. 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

  14. 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

  15. GRIPS Task 3c KU NIES SSU-satellite data, 1979-03 WACCM MRI Freie Universität Berlin Annual mean temperature change(K/decade) FUB

  16. 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!

  17. 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.

  18. 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

  19. 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)

  20. CCMVal ongoing activities Coupled chemistry models Shine et al., 2003 • Previous CCM studies Annual and global mean temperature change

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

  22. CCMVal ongoing activities to do: update Shine et al. CCM figure for CCMval models

  23. CCMVal ongoing activities • Some results from tropical analyses • Performed within SCOUT-O3 (Workpackage 1.9) at FUB

  24. Temperature

  25. 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

  26. Tropopause Temperature – – – – –

  27. Temperature trend at 70 hPa

  28. 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 ?

  29. 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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