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Stratospheric Temperature Changes: Ozone Impact Study

This study explores the attribution of stratospheric thermal and dynamical changes to ozone alterations using various models. It examines ozone perturbations, GCM and CCM studies, and assesses temperature variations due to observed ozone trends. The research aims to enhance climate change assessments and model improvements.

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Stratospheric Temperature Changes: Ozone Impact Study

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  1. Temperature and circulation changes in the stratosphere - Summary of previous workand outlook - Ulrike Langematz

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

  3. 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)

  4. 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

  5. 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)

  6. GCM Ozone perturbations studies I MA-GCM studies of the period 1980-2000 with prescribed ozone profile changes: • Rosier and Shine, 2000 • Langematz, 2000, Langematz et al., 2003 • Ramaswamy and Schwarzkopf, 2003 • Schwarzkopf and Ramaswamy, 2003 Shine et al., 2003

  7. Previous studies Freie Universität Berlin Annual and global mean temperature change due to observed O3 trend Models using Height-Resolved Observed Ozone Trends Dataset – 1.25 to – 2.3 K/dec – 0.25 to – 0.45 K/dec Shine et al., 2003

  8. Previous studies ? Freie Universität Berlin Annual mean temperature change at 50 hPa Models using Height-Resolved Observed Ozone Trends Dataset Shine et al., 2003

  9. Previous 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. Previous studies Coupled chemistry models Shine et al., 2003  Lower/middle stratosphere Annual and global mean temperature change

  11.  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

  12. 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)

  13. 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 model experiments using R&W and L- ozone trends UM model

  14. GRIPS Task 3c WACCM NIES MRI KU FUB Freie Universität Berlin Annual and global mean temperature change (K/decade) altitude [km]

  15. 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

  16. 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

  17. GRIPS Task 3c SW heating rate change [K/d/dec] WACCM NIES MRI KU FUB Ozone change [%/decade] R&W-O3 L-O3 NH summer (JJA) change, 30°N Temperature [K/dec] To do: temperature change per ozone change, in progress

  18. 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!

  19. 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.

  20. GRIPS Task 3c KU NIES WACCM MRI Freie Universität Berlin Temperature change in DJF (K/decade) FUB

  21. u [m/s/decade] weaker residual circulation D [m/s/day/decade] DJF change in zonal wind, wave forcing, and residual circulation, 1980-2000 FUB-CMAM (with prescribed O3 change) v* [m/s/decade] stronger polar night jet latitude w* [mm/s/decade] weaker wave driving Orange (yellow): 99% (95%) stat. significance. latitude Langematz et al., 2003 Stratospheric ozone change causes dynamical changes.

  22. GRIPS Task 3c KU FUB MRI Change in wave forcing in NH winter (DJF) [m/s/day/decade]

  23. GRIPS Task 3c KU FUB NI MRI Change in residual vertical velocity in NH winter (DJF) [mm/s/decade]

  24. GRIPS Task 3c Freie Universität Berlin Zonal wind change in DJF (m/s/decade) KU NIES FUB WACCM MRI Models do not show a consistent dynamical response.

  25. GRIPS Task 3c NIES FUB MRI Freie Universität Berlin Change in polar vortex strength in NH spring (dam/decade) Trend 1979-2000 FUB-data March 90‘s-70‘s (1991-2000)-(1971-1980) FUB-data

  26. GRIPS Task 3c 100hPa transient 100hPa equilibrium Equilibrium vs. transient response in WACCM Temperature, annual mean, [K/decade]

  27. 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

  28. 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

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