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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
sandip@iup.physik.uni-bremen.de 11/11/03
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
sandip@iup.physik.uni-bremen.de 11/11/03
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
sandip@iup.physik.uni-bremen.de 11/11/ 03
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
sandip@iup.physik.uni-bremen.de 11/11/ 03
Northern Hemisphere
sandip@iup.physik.uni-bremen.de 11/11/ 03
Tropics (50 hPa)
One of longest westerly phases of QBO (1993-1996)
sandip@iup.physik.uni-bremen.de 11/11/ 03
tropics
Polar
Mid-latitudes
sandip@iup.physik.uni-bremen.de 11/11/ 03
No SSW since last 17 years in Jan.
-1.2 K/decade in Nov. and Dec.
sandip@iup.physik.uni-bremen.de 11/11/ 03
SH – pre-satellite period – Problem?
sandip@iup.physik.uni-bremen.de 11/11/ 03
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%
sandip@iup.physik.uni-bremen.de 11/11/03
13%
25%
12 %
sandip@iup.physik.uni-bremen.de 11/11/03
8%
8%
11%
sandip@iup.physik.uni-bremen.de 11/11/03
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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