Dynamical Influence on Inter-annual and Decadal Ozone Change @iup.physik.uni-bremen.de Sandip...

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Dynamical Influence on Inter-annual and Decadal Ozone Change

http://www.iup.physik.uni-bremen.desandip@iup.physik.uni-bremen.de

Sandip Dhomse, Mark Weber, J.P.

Burrows

Universtät Bremen FB1, Institüt für

Umweltphysik (iup)

Outline

• Introduction• Data used• Inter-annual variability• Decadal variability• Tele-connection patterns

(Introduction)• Summary and Conclusion• Outlook

sandip@iup.physik.uni-bremen.de 11/11/03

No abrupt change in chemical composition

Introduction

sandip@iup.physik.uni-bremen.de 11/11/03

Sun - at the same position

sandip@iup.physik.uni-bremen.de 11/11/03

Total Ozone is higher in NH (spring) than SH (spring)

Low TOZ

In tropics

Relatively High TOZ in tropics during SH spring

Wave activity controls

• Stratospheric

circulation

• Stratosphere

Troposphere

Exchange

sandip@iup.physik.uni-bremen.de 11/11/03

Holton et al., 1995

SH winter- colder

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Mean Winter temp. (shaded) And zonal wind (contour) for NH and SH

SH – polar jet stronger

Tropopause colder during NH winter

Planetary waves

Planetary waves are large-scale distortions to the mean flow

The flow (black) meanders across latitude circles (blue).

V

V

sandip@iup.physik.uni-bremen.de 11/11/03

Examples of wave patterns

Wave 1 pattern

Wave 2 pattern

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Brewer-Dobson circulation

•Breaking planetary waves apply a FORCE to the winds-

decelerates the speed

•Pressure gradient force- remains unaffected

•Corioli’s force - REDUCED so there is a net force towards the

pole.

•Air RISES over the equator, drifts steadily POLEWARD

(while meandering around the latitude circles) and SINKS at

the poles

sandip@iup.physik.uni-bremen.de 11/11/03

sandip@iup.physik.uni-bremen.de 11/11/03

Two components of EP flux are calculated as,(Andrews,et.al 1987)

)''/'']/)cos()cos({[cos

)''/''(cos

10

)(

0)(

uwvuuafaF

uvvuaF

zzz

zz

And its divergence is

z

FFaF

z

)cos()cos( 1

• Eliassen Palm (EP) flux vector is a measure of the upward propagating momentum carried by planetary waves

• The divergence of EP flux gives the volume where momentum is deposited

Measuring the wave activity

Heat flux

Momentum flux

sandip@iup.physik.uni-bremen.de 11/11/03

Measuring the wave activity

)))(((''

)))(((''

TTvvmeanTv

vvuumeanvu

zonalzonal

zonalzonal

''vuF

''TvF z

sandip@iup.physik.uni-bremen.de 11/11/03

Data used

Meteorological data set • ERA40 - 23 pressure levels• ERA15 - 17 pressure levels• UK Met. Office - 22 pressure levels • ECMWF - 21 pressure levels• NCEP - 17 pressure levels

Ozone data set• GOME - total ozone data • TOMS - total ozone data

sandip@iup.physik.uni-bremen.de 11/11/ 03

sandip@iup.physik.uni-bremen.de 11/11/ 03

Inter-annual variation of flux and Ozone

High flux - increase in Brewer-Dobson circulation - more transport

sandip@iup.physik.uni-bremen.de 11/11/ 03

Record high lower stratosphericheat flux on 20th/21stSeptember (ERA40 1960-2002)

Splitting of the polar vortex on 26th September 2002

First major stratospheric warming in SH

sandip@iup.physik.uni-bremen.de 11/11/ 03

wave activity and winter gain in ozone

Weber et al. 2003

High correlation between winter heat flux (wave activity) and spring/fall ozone ratio

Winter ozone gain in Antarctic 2002 presents an intermediate case between other Antarctic winters and cold Arctic winters (higher contribution from transport)

High Heat flux –Low PSC

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sandip@iup.physik.uni-bremen.de 11/11/ 03

Does dynamics the same? Or Chemistry is changing?

Model Differences

ERA40

ERA40 +ERA15

sandip@iup.physik.uni-bremen.de 11/11/ 03

Decadal Variation?

And Difficulties in trend analysis

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Northern Hemisphere

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Tropics (50 hPa)

One of longest westerly phases of QBO (1993-1996)

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tropics

Polar

Mid-latitudes

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No SSW since last 17 years in Jan.

-1.2 K/decade in Nov. and Dec.

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SH – pre-satellite period – Problem?

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PSC volume using ERA40 data

T <195 K (PSC volume)

SH (JAN-DEC)NH (JUL-JUN)

sandip@iup.physik.uni-bremen.de 11/11/ 03

Days (Jul-Jun)

195 K- PSC temperature

SH –colder temperature

Days (Jan-Dec)

sandip@iup.physik.uni-bremen.de 11/11/ 03

No significant trend in heat flux

sandip@iup.physik.uni-bremen.de 11/11/ 03

Different models – different trends

sandip@iup.physik.uni-bremen.de 11/11/ 03

No significant trend in any dataset in heat flux as well as EP Flux

sandip@iup.physik.uni-bremen.de 11/11/03

Summary

• Strong correlation between seasonal heat flux and total ozone in March.

• No significant trend on seasonal scale in heat flux.

• Maximum cooling trend is in November and January ( -1.2 K/decade) , but there is not trend in heat flux.

• Different models, different periods lead to different trends.

sandip@iup.physik.uni-bremen.de 11/11/03

Bremen- 10/23/2003

sandip@iup.physik.uni-bremen.de 11/11/03

Arctic Oscillation

sandip@iup.physik.uni-bremen.de 11/11/03

Arctic Oscillation

From National Geographic Magazine March-2000

sandip@iup.physik.uni-bremen.de 11/11/03

Arctic Oscillation

source : http://www.ldeo.columbia.edu

sandip@iup.physik.uni-bremen.de 11/11/03

28%

30%

45%

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13%

25%

12 %

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8%

8%

11%

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Conclusion

• There are no significant trends in 2D (latitude & altitude) analysis of the data.

• 3D analysis of data will be useful to find the dependence of ozone on different tele-connection patterns.

• EOF analysis is good tool for 3D analysis.

sandip@iup.physik.uni-bremen.de 11/11/03

Outlook

• Study ozone dependence on different tele-connection pattern using EOF technique.

• Find out different patterns in the ozone variability using GOME vertical profile data (neural network) , TOMS, SAGE, POAM, ozonesonde datasets.

Thank you very much for your kind attention!!!

sandip@iup.physik.uni-bremen.de 11/11/03

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