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Global Ozone:Past and Present

Abhinand Jha

PEP

Universität Bremen

Presented for Presentation Tech. Course

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Overview1 Motivation

2 General Introduction

3 Ozone Change Updates

4 Other tracers of O3

5 Political Scenario

6 Summary

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Motivation

Ozone hole's growth rate slows down

Scientists credit refrigerant ban

U.N. says 'ozone hole' hits record size

Antarctica ozone hole grows larger this year

2003 Antarctic Ozone Hole grows fast, But recovery Forecast

WMO report 2006

21/11/2007 Figures from WMO 2006 4

General Introduction

21/11/2007 5

Total Ozone column Vertical Ozone column

General Idea

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Chemical and dynamic processes contributing in Ozone variations

1 Solar cycle variations (11 year cycle)

2 QBO (quasi biennial oscillations)(27-month cycle)

3 Volcanic eruptions (effects for few years)

4 EESC (Equivalent effective stratospheric chlorine)

More Emphasis on EESC

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EESC (Equivalent Effective Stratospheric Chlorine)

1 Ozone-depleting substances release their halogen once they reach the stratosphere.

2 The efficiency for bromine (Br) and chlorine (Cl) in destroying ozone is very high.

3 EESC is a measure of overall stratospheric ozone-depleting halogen.

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Ozone change updates

21/11/2007 Figures from WMO 2006 9

Updated Results

Ozone variations for 60o S to 60o N due to different atmospheric processesElchichon and

Mt.Pinatubo

Linear Trend

Scaled and fitted EESC(Eq.Eff.Stratospheric Chlorine) with ozone column

O3 changes can be expressed

• In terms of EESC,

• Differences between time periods of EESC

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Statistical Methods1 Multiple Linear Regression - Try to relate the explanatory variables of

ozone to ozone data !!Problem: How proxies are included in the

model???

2 The EESC Function -Analyze changes in ozone (which reflects

amount of Cl and Br to deplete O3)

!! Problem: Polar EESC is not included

21/11/2007 Figures from WMO 2006 11

Total Ozone Changes

1 Satellite data from Total Ozone mapping Spectrometer (TOMS)

2 Solar backscatter ultraviolet (SBUV)

Annual Avarages

Annual Avarages

21/11/2007 Figures from WMO 2006 12

Ozone Changes in Tropics

1 Maximum ozone in tropics(40%).

2 Small changes but not statistically significant

Ozone column is unchanged at the equator

21/11/2007 Figures from WMO 2006 13

Seasonal Ozone variations

Ozone Minimum due to volcanic eruptions(Mt.Pinatubo)

Low due to regular spring time ozone deplition

Clear Difference between NH and

SH mid-latitudes.

21/11/2007 Figures from WMO 2006 14

Vertical Distribution of Ozone

Measured by

1 Ozone Sondes (30-35km)

2 Lidar and Microwave instruments (from lower stratosphere to 50 km)

3 Dobson- Brewer Instruments(ground based profile data up to 50km)

4 Satellite observations (SAGE, SBUV, SBUV/2)

1 Upper Stratosphere

Long term decline of ozone till 1996 but then the trend seem to be constant

21/11/2007 Figures from WMO 2006 15

2 Lower Stratosphere

Ozone reached minimum values till 1993 but now they are again recovering to the values of early 1980‘s

21/11/2007 Figures from WMO 2006 16

3 Latitudinal Ozone Profiles

Tropical differences ….?????

Vertically integrated SAGE I+II data,compared with results from the merged TOMS/SBUV column ozone dataset.

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4 Tropospheric Ozone (TO)

1 Changes in TO are regional

2 The trends within the region changed over last 25-35 years

Increase of TO over Canada and decrease over Europe and Japan

43%±25%/decade increase of TO over Delhi

Ozone data at Cruise Altitudes

(7.7-11.3km) increased by 1ppb/year

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Other Tracers of Ozone

21/11/2007 Figures from WMO 2006 19

Stratospheric Aerosol and NO2

Aerosol Sources :

1 Volcanic Activities (El Chichón and Mt.Pinatubo)

2 Some SO2 by Human-related activities

NO2 Sources :

1 Natural sources: Oxidation of ammonia in soils.

2 Man-made source: Vehicular fuel combustion

and industrial output.

But Stratospheric Aerosol remains near non-volcanic background

Short data records and hemispheric differences in trends are unexplained??

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Political Scenario

1 WMO is a specialized agency of the United Nations (UN).

2 The results produce by WMO gives an overview of changing climate and making new governmental policies about climate change.

http://www.wmo.ch/pages/about/index_en.html

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SummaryTotal Ozone Column

1 Global mean of total column ozone values shows ozone is no longer decreasing.

2 Total column ozone in Southern Hemisphere (SH) and Northern Hemisphere (NH) mid-latitudes has recovered.

3 Seasonal differences in SH and NH are shown clearly.

4 Total column Ozone over tropics is unchanged.

Vertical Ozone Distribution

1 Upper Stratosphere ------- no more Ozone decline.

2 Lower Stratosphere ---- ozone is constant with significant variability.

3 Troposphere --- Not a consistent trend.

Will it remain constant???

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Thank You For

listening!!!!!!!!!!!!

Comments!!!!

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