Effect of Stratospheric Water Vapor Change on Ozone Layer and Climate

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. JasonLader at Leeds University

1,2 2

Climate is Changing !Observations Modelling

Not believe or believe but no action.

Believe and dosomething.

•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 Dayafter Tomorrow’

Ozone Layer: What Does It Mean to Us

Effects of the reduction of ozone

1. 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.

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?

Evolution of Ozone Hole

From web page: http://www.theozonehole.com

Stratospheric Water Vapour Is Increasing

Oltmans, S., et al (2000, GRL)

Increase H2O

Decrease temperature

Increase OH

Slow down O3 depletionMore O3 loss

Net effect : reduce ozone or increase ?

More PSCs

More O3 loss

Role of H2O in Stratospheric ozone depletion

Global warming will increase tropospheric H2OSources leading to stratospheric H2O increaseare still not well understood.

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

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

Age of Air and Importance of Coupling

Chemistry and climatecoupling is important!

Maximum 0.5 yeardifference in the meanage of air in the stratospherecan be induced by chemistrycoupling.

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.

R1 A run which is identical to Control Run R0 except that H2O field in the chemistry 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.

Six Integrations

R5 A run with 2100 conditions.

R0 Control run with 2000 conditions

Chemistry Related Effects of H2O

R1 – R0 (Time and zonal averaged fields)

T CH4

Responses of the atmosphere to 2ppmvH2O increase in the chemistry.

Note that CH4 decreases implying thattransport of CH4 from troposphere tostratosphere is slowing down or moreCH4 oxidation.

Radiation Related Effects of H2O

R3 – R2 (Time and Zonal Averaged Fields)

CH4 Overall increase in CH4 implying anincreased stratospheric wave forcing

The cooling of stratosphere isevident.

T

Ozone Changes

Radiative Effects on 2ppmv WaterVapor increase

Chemical Effects on 2ppmv WaterVapor increase

Temperarure Changes

Note the offset effect on ozone.

SignificantCooling!

Radiative + Chemical Effects

Dynamic Response to Increasing H2O

Chemistry-induced Response Radiation-induced Response

Winter

Summer

Spring

Autumn

Winter

Summer

Spring

Autumn

R0

R1

R0

R1

R2

R3

R2

R3

Recovery of Ozone Layer

Arctic in March

A persistent recovery of polar ozone from 2000 to 2100

Antarctic in September

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.