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Temperature and circulation changes in the stratosphere - Summary of previous workand outlook -

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.

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Temperature and circulation changes in the stratosphere - Summary of previous workand outlook -

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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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