Edited by L. Thomason and Th. Peter

WCRP-124
WMO/TD- No. 1295
SPARC Report No. 4

Citation:

SPARC, 2006: SPARC Assessment of Stratospheric Aerosol Properties (ASAP). L. Thomason and Th. Peter (Eds.), SPARC Report No. 4, WCRP-124, WMO/TD – No. 1295, available at www.sparc-climate.org/publications/sparc-reports/	BibTex	Endnote

Table of Contents

Foreword

Disclaimer

Executive Summary

Key Findings

Recommendations

Important Findings Per Chapter

Chapter 1: Stratospheric Aerosol Processes

Chapter 2: Precursor Gas Measurements

Chapter 3: Instruments

Chapter 4: Stratospheric Aerosol Record and Climatology

Chapter 5: Stratospheric Aerosol Trends

Chapter 6: Modeling of Stratospheric Aerosols

ASAP Data Archive

List of Reviewers

Chapter 1 – Stratospheric Aerosol Processes

1.1 The Importance of Stratospheric Aerosol

1.2 The Life Cycle of Stratospheric Aerosol

1.3 Sources of Sulfur Gases and Aerosol to the Stratosphere

1.4 Stratospheric Aerosol Microphysics and the Particle Size Distribution
1.4.1 Global Aerosol
1.4.2 Polar Aerosol
1.4.3 Non-Aqueous Stratospheric Particles

1.5 Volcanic Perturbations to Stratospheric Aerosol

1.6 Aerosol in the Tropopause Region
1.6.1 Aerosol precursors and nucleation processes
1.6.2 Aerosol distribution and composition

1.7 Polar Stratospheric Clouds and Sub-visible Cirrus Clouds
1.7.1 Polar Stratospheric Clouds
1.7.2 Subvisible Cirrus Clouds

1.8 Aviation-produced aerosol

Chapter 2 – Precursor Gas Measurements

2.1 Introduction

2.2 Dynamics and Atmospheric Transport

2.3 Sulfur Chemistry

2.4 Observations
2.4.1 Carbonyl sulfide (OCS)
2.4.2 Sulfur Dioxide (SO₂)
2.4.3 Dimethyl sulfide (CH₃SCH₃)
2.4.4 Other precursor gases

2.5 Fluxes
2.5.1 Carbonyl Sulfide Fluxes
2.5.2 Sulfur Dioxide Fluxes
2.5.3 Dimethyl Sulfide Fluxes
2.5.4 Hydrogen Sulfide Fluxes
2.5.5 Methyl Mercaptan Fluxes
2.5.6 Carbon Disulfide Fluxes
2.5.7 Meteors, cosmic radiation, and rocket exhaust
2.5.8 Isotopic studies

2.6 Summary and open question

2.7 Acknowledgements

Chapter 3 – Instruments

3.1 Introduction

3.2 Global Long-Term Measurements
3.2.1 SAM II, SAGE I, and SAGE II: The Occultation Technique
3.2.2 HALOE
3.2.3 POAM II and POAM III

3.3 Global Short-Term Measurements
3.3.1 CLAES
3.3.2 ORA

3.4 Localized Long-Term Measurements
3.4.1 Balloon Borne Optical Particle Counter
3.4.2 Lidar Systems

3.5 Localized Short-Term Measurements
3.5.1 The Aircraft-Borne LaRC Aerosol Lidar
3.5.2 The Airborne DLR OLEX Lidar
3.5.3 Airborne Particle Counters
3.5.4 Balloon-borne Backscattersonde

Chapter 4 – Stratospheric Aerosol Record and Climatology

4.1 Introduction

4.2 Primary Measured Aerosol Properties
4.2.1 Global Long-term Measurements of Extinction and Optical Depth
4.2.2 Global Short-term Measurements
4.2.3 Localized Long-term Measurements
4.2.4 Short Term Localized Measurements

4.3 Retrieved Products
4.3.1 Retrieved Products from Global Long-term Measurements
4.3.2 Retrieved Products from Localized Long-term Measurements
4.4 Relevant Cross-Comparisons Of Averages Or For Coincidences
4.4.1 SAGE/HALOE/OPC Comparisons
4.4.2 SAGE/POAM Comparisons
4.4.3 SAGE/ORA Comparison
4.4.4 Comparisons of SAGE Extinctions with Lidar Backscatter

4.5 Conclusions

Chapter 5 – Stratospheric Aerosol Trends

5.1 Introduction

5.2 Fundamental measurements
5.2.1 In situ measurements
5.2.2 Remote lidar measurements
5.2.3 Remote satellite measurements

5.3 Measurements

5.4 Investigation of trends in the long term aerosol measurement records
5.4.1 Comparison of stratospheric aerosol during non-volcanic periods
5.4.2 Removing the volcanic signal from the long term measurement records

5.5 Discussion
5.5.1 Aerosol surface area: Differences between satellite and in situ measurements
5.5.2 Estimates of global stratospheric aerosol burden during background conditions

5.6 Summary and Conclusions

Chapter 6 – Modeling of Stratospheric Aerosols

6.1 Summary

6.2 Scope and Rationale

6.3 Model Descriptions

6.4 Model Illustrations of Aerosol Microphysics

6.5 Model Simulations of Non-volcanic Conditions
6.5.1 Description of Calculations
6.5.2 Comparisons to Precursor Gas Measurements
6.5.3 Calculated Aerosol Budgets and Burdens
6.5.4 Comparisons to Satellite Extinction Measurements
6.5.5 Comparisons to Derived Satellite Products

6.6 Sensitivity Studies and Analyses
6.6.1 Sensitivity to model formulation
6.6.2 Primary aerosol sensitivity
6.6.3 Tropopause SO₂ sensitivity
6.6.4 OCS sensitivity

6.7 Model Simulations of Volcanic Conditions
6.7.1 Description of Calculations
6.7.2 Comparisons with Lidar Backscatter Measurements
6.7.3 Comparisons with SAGE II Observations
6.7.4 Comparisons with OPC Data
6.7.5 Aerosol Decay Rates

6.8 Discussion
6.8.1 Uncertainties
6.8.2 Future Trends of Stratospheric Sulfate Aerosols
6.8.3 Conclusions

References

Appendices

I WCRP Reports

II Acronyms and Abbreviations

III Authors, Co-authors, and Contributors