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Effect of Stratospheric Water Vapor Change on Ozone Layer and Climate

Effect of Stratospheric Water Vapor Change on Ozone Layer and Climate. 1,2. 2. Wenshou Tian Martyn P. Chipperfield 1 Collage of the Atmospheric Science Lanzhou University, Lanzhou, Gansu, China 2 Institute for Atmospheric Science,

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Effect of Stratospheric Water Vapor Change on Ozone Layer and Climate

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  1. Effect of Stratospheric Water Vapor Change on Ozone Layer and Climate 1,2 2 Wenshou Tian Martyn P. Chipperfield 1 Collage of the Atmospheric Science Lanzhou University, Lanzhou, Gansu, China 2 Institute for Atmospheric Science, School of the Earth and Environment, University of Leeds, UK Acknowledgments. Dr. Peter Braesicke from Cambridge University; Dr Alan Iwi and Dr J. Kettleborough from RAL, Dr Jeff Cole from University of Reading; Dr. Jason Lader at Leeds University

  2. Observations Modelling Climate is Changing ! • The average global • temperature is likely • to rise 1.1 to 6.4 K • by 2100. • Correspondingly, the • sea level may rise 16 • to 120 cm (Joel Smith, • 2001) • Severe ozone loss begins • to be observed in Arctic • frequently (e.g. Rex et al, • 2004 GRL). Arctic ozone • hole may appear in the • near future? ‘The Day after Tomorrow’ Not believe or believe but no action. Believe and do something.

  3. Ozone Layer: What Does It Mean to Us • Effects of the reduction of ozone • The ultraviolet radiation reaching the ground • increases about 2% for each 1% decrease in the atmospheric ozone. • 2. The UV with wavelength equaling 0.26um attacks DNA or reproductive molecules in all living systems. • 3. EPA estimated that a 1% drop in the global ozone could cause 20,000 additional skin cancers in the US annually.

  4. Where are we? • The amendments to the Montreal protocal have resulted a decrease in stratospheric halogen loading. Consequently, ozone is expected to start to recover. Recover point?

  5. Evolution of Ozone Hole From web page: http://www.theozonehole.com

  6. Stratospheric Water Vapour Is Increasing Oltmans, S., et al (2000, GRL)

  7. Role of H2O in Stratospheric ozone depletion Global warming will increase tropospheric H2O Sources leading to stratospheric H2O increase are still not well understood. More PSCs Increase H2O Increase OH Decrease temperature More O3 loss Slow down O3 depletion More O3 loss Net effect : reduce ozone or increase ?

  8. Issues to be Addressed • What is the role of the chemical and radiative effects of H2O on the stratospheric O3 depletion and temperature change • How does the stratospheric O3 look like by 2100 Science, 1998, by David Rind

  9. The Chemistry Climate Model (CCM) CCM = Unified Model + SLIMCAT chemistry + STOCHEM UM version 4.5 with a resolution 2.5o x 3.75o. 64 Levels (surface – 0.01 hPa). Chemistry coupled to the UM radiation scheme through modelled O3, H2O, CH4 and N2O. Details in Tian and Chipperfild, 2005,QJRM,281-303

  10. Age of Air and Importance of Coupling Chemistry and climate coupling is important! Maximum 0.5 year difference in the mean age of air in the stratosphere can be induced by chemistry coupling.

  11. Six Integrations R0 Control run with 2000 conditions R1 A run which is identical to Control Run R0 except that H2O field in the chemistry scheme is increased by 2ppm. R2 A fully coupled run in which O3, N2O, CH4, and H2O from chemistry are coupled to the UM radiation scheme. R3 A fully coupled run in which stratosphere H2O used in radiation scheme is increased by 2ppm. R4 A run with 2050 conditions. GHG, and halocarbon scenarios are from IPCC (2001). Other configurations are the same as Control Run. R5A run with 2100 conditions.

  12. Chemistry Related Effects of H2O R1 – R0 (Time and zonal averaged fields) Responses of the atmosphere to 2ppmv H2O increase in the chemistry. Note that CH4 decreases implying that transport of CH4 from troposphere to stratosphere is slowing down or more CH4 oxidation. CH4 T

  13. Radiation Related Effects of H2O R3 – R2 (Time and Zonal Averaged Fields) The cooling of stratosphere is evident. T Overall increase in CH4 implying an increased stratospheric wave forcing CH4

  14. Radiative + Chemical Effects Ozone Changes Chemical Effects on 2ppmv Water Vapor increase Radiative Effects on 2ppmv Water Vapor increase Note the offset effect on ozone. Temperarure Changes Significant Cooling!

  15. Dynamic Response to Increasing H2O Chemistry-induced Response Radiation-induced Response R2 R0 Winter Spring Winter Spring R3 R1 R2 R0 Summer Autumn Summer Autumn R3 R1

  16. Recovery of Ozone Layer Arctic in March Antarctic in September A persistent recovery of polar ozone from 2000 to 2100

  17. Summary and Conclusion 1 Increasing H2O in radiation gives rise to an overall increase in the total column ozone, particularly in the northern high latitudes. 2 Increasing H2O in chemistry leads to an increase in total column ozone in the northern high latitudes and more ozone depletion in the southern high latitudes. 3 From 2000 to 2100, a persistent ozone recovery can be noted in both the Artic and Antarctic stratosphere. The Arctic ozone by 2100 seems to be unlikely.

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