1 -- INTRODUCTION

 

1.1 Lecture Objectives

1.2 Basic overview of the Antarctic ozone hole: discovery, observations and theory

1.3 Overview of each section of this lecture

 

2 -- HISTORICAL BACKGROUND: OBSERVATIONS OF AND EARLY HYPOTHESES FOR THE EXISTENCE OF THE ANTARCTIC OZONE HOLE

 

2.1 Ozone Observations

2.2 Ozone Theories

      2.2.1 Dynamical theory

      2.2.2 Nitrogen oxide theory

      2.2.3 Heterogeneous chemistry theory

 

3 – THE ANTARCTIC POLAR VORTEX

 

3.1 Winds

      3.1.1 Evolution of the polar night jet and the polar vortex

3.2 Temperature

      3.2.1 Evolution of south polar cold temperatures during the winter

3.3 Potential Vorticity

      3.3.1 The polar vortex: isolated and contained

      3.3.2 Demonstrating characteristics of potential vorticity with trajectory modeling studies

3.4 Heating

3.5 Transport

      3.5.1 Vertical motions and ozone transport

      3.5.2 Nitrous oxide as tracer of stratospheric motions

      3.5.3 Wintertime stratospheric circulation: the Brewer-Dobson cell

 

4 -- STRUCTURE AND DYNAMICS OF THE ANTARCTIC OZONE HOLE

 

4.1 Horizontal Structure

      4.1.1 Almost symmetric

      4.1.2 Wave One structure

      4.1.3 Highly mobile; eastward rotation

4.2 Vertical Structure

      4.2.1 Mixing ratio and density

      4.2.2 Ozonesonde vertical (partial pressure) profiles

4.3 Annual Cycle of Antarctic Ozone

      4.3.1 Evolution of ozone hole in 1992

      4.3.2 Minimum ozone amounts: 1992 Versus 1996

      4.3.3 Determining the size of the ozone hole from the TOMS record 1979-1996

               (a) Why the 220 DU contour?

               (b) Annual cycle in ozone hole size

               (c) Average size of the ozone hole, 1979-1996

               (d) Vertical range and severity of ozone hole

                    (1) POAM II satellite data

                    (2) McMurdo Base, Antarctica balloon data

               (e) Hemispheric perspective of the ozone hole using MLS satellite data

4.4 Ozone Hole Break-Up

4.5 Section 4 Summary

5 -- WHY THE ANTARCTIC OZONE HOLE EXISTS: OZONE HOLE THEORY

5.1 Polar Stratospheric Clouds

      5.1.1 Comparing Type I and Type II PSCs

      5.1.2 Denitrification and Dehydration of the Stratosphere

      5.1.3 PSC Formation: Hemispheric Differences in Temperature

5.2 Heterogeneous Reactions

      5.2.1 Heterogeneous Versus Homogeneous Chemical Reactions

      5.2.2 Principal Heterogeneous Reactions

      5.2.3 Denoxification of the Antarctic Stratosphere

      5.2.4 In Situ Measurements of Reactive Chlorine Inside the Polar Vortex

5.3 Catalytic Ozone Loss

      5.3.1 Catalytic Loss of Ozone: ClO-ClO Reaction

      5.3.2 Catalytic Loss of Ozone: BrO-ClO Reaction

      5.3.3 Catalytic Loss of Ozone: ClO-O Reaction

5.4 Evolution of the Ozone Hole Through a Season

      5.4.1 Chlorine Activation and Nitrogen Denoxification

      5.4.2 Return of Sunlight and More Heterogeneous Chemistry

      5.4.3 UARS Observations of Antarctic Vortex Trace Gas Concentrations

               September 17, 1992

      5.4.4 UARS Observations of Trace Gases Inside the Antarctic Vortex for

               Selected Days in 1992

               (a) ClO Observations

               (b) ClONO2 Observations

               (c) HNO3 Observation

6 -- THE SEARCH FOR ARCTIC OZONE LOSS

6.1 Observations of Ozone Loss in the Arctic from 1988 to 1995

      6.1.1 The AASE-I Mission: Various Findings

      6.1.2 UARS Measurements and the AASE-II and EASOE Missions: Various Findings

6.2 Arctic Ozone from 1996 to 1998

6.3 Arctic Ozone Compared to Antarctic Ozone

6.4 Future of Arctic Ozone

6.5 Future of the Ozone Hole Phenomenon 

SUMMARY OF CONDITIONS NECESSARY FOR AND STEPS INVOLVED IN OZONE LOSS

REVIEW QUESTIONS

REFERENCES