The Stratospheric Aerosol Layer

ISBN-13: 9783642817595 / Angielski / Miękka / 2011 / 156 str.

R. C. Whitten

Opis

It is now a quarter of a century since Junge and his coworkers recovered the first sample from the sulfate aerosol layer in the stratosphere. Since that time vast strides have been made in determining its physical properties and morphology. These investigations have been performed with instruments on board aircraft and balloon platforms as in the early days, with ground-based lidar (optical radar), and most recently with satellite-borne optical instruments. It will become evident in Chapter 2 that in situ measurements by aircI'aft and, balloon sensors complement rather than duplicate the remote techniques (lidar and satellite). Hence future programs will probably continue to utilize direct as well as indirect experimental techniques. Concurrently, with the observations of the gross properties of the aerosol layer, la oratory and theoretical studies have sought to elucidate the chemical and micro physical processes which influence the formation and growth of the aerosol par ticles. The laboratory investigations have included studies of gas phase chemistry, and particle nucleation and growth mechanisms. Theoretical studies have revolved mainly around a series of models developed by atmospheric scientists. The earliest of these models was constructed by Junge and his colleagues. With the advent of third- and fourth-generation computers, the capacity to solve the quite complex continuity equations whi h govern particle formation, growth, and removal has ad vanced to the point where most of the particle properties can be simulated with reasonable confidence."

Spis treści

1. Introduction.- 1.1 General Discussion.- 1.1.1 Historical.- 1.1.2 Particle Measurements.- 1.1.3 Measurements of Precursor Gases.- 1.1.4 Laboratory Measurements.- 1.1.5 Models of the Aerosol Layer.- 1.2 Influence on Climate.- 1.3 Microphysical Processes.- 1.3.1 Nucleation.- 1.3.2 Condensation and Evaporation.- 1.3.3 Coagulation.- 1.3.4 Sedimentation.- 1.3.5 Transport.- References.- 2. Observations.- 2.1 Measurements of Precursor Gases in the Stratosphere.- 2.1.1 In Situ Mass Spectrometer Method.- 2.1.2. In Situ Filter Collection.- 2.1.3 In Situ Cryogenic Collection.- 2.1.4 Remote Sensing Methods.- 2.1.5 Summary of Stratospheric Observations of Sulfur Gases.- 2.2 Aircraft and Balloon Measurement of Aerosol Properties.- 2.2.1 Aerosol Constituents.- 2.2.2 Aerosol Properties.- 2.2.3 Detection Methods.- 2.2.4 Analytical Techniques.- 2.2.5 Statistical Treatments.- 2.2.6 Aitken Nuclei.- 2.2.7 Larger Acid Droplets.- 2.2.8 Granular Inclusions.- 2.2.9 Cosmic Dust.- 2.2.10 Volcanic Ash.- 2.2.11 Variations.- 2.2.12 Discussion.- 2.3 Lidar Measurements.- 2.3.1 The Lidar Technique.- 2.3.2 Survey of Results.- 2.3.3 Comparisons of Lidar and Other Results.- 2.3.4 Additional Applications.- 2.4 Satellite Observations.- 2.4.1 Present Spacecraft Experiments.- 2.4.2 Orbital Considerations.- 2.4.3 Results Obtained with SAM II.- 2.4.4 Results Obtained with SAGE.- 2.4.5 Ground-Truth Comparisons.- 2.4.6 Applications.- References.- 3. The Chemical Kinetics of Aerosol Formation.- 3.1 Chemical Origin.- 3.2 Nucleation.- 3.3 Nucleation Mechanisms in the Stratosphere.- 3.3.1 Binary Nucleation.- 3.3.2 Ternary Nucleation.- 3.3.3 Binary Heterogeneous Nucleation.- 3.3.4 Heteromolecular Nucleation.- 3.4 Growth and Heterogeneous Reactions.- 3.5 Conclusions.- References.- 4. Models of Stratospheric Aerosols and Dust.- 4.1 Overview.- 4.2 The Generalized Aerosol Continuity Equation.- 4.3 Aerosol Models.- 4.3.1 The Simulated Distributions of Aerosol Precursor Gases.- 4.3.2 Aerosol Nucleation Models.- 4.3.3 Calculated Properties of the Aerosols.- 4.4 Models of Upper Atmospheric Dust.- 4.5 Anthropogenic Perturbations of the Aerosols.- 4.6 Conclusions.- References.- 5. Stratospheric Aerosols and Climate.- 5.1 Background.- 5.2 Statistical Relations Between Volcanic Explosions and Climatic Changes.- 5.2.1 Changes Observed After Single Eruptions.- 5.2.2 Changes Observed During Epochs of Volcanic Activity.- 5.3 Theoretical Relationships Between Volcanic Explosions and Climate.- 5.3.1 Radiative Properties of the Aerosols.- 5.3.2 Sensitivity Studies of the Effects of Aerosols on Climate.- 5.3.3 Theoretical Studies of the Effect of Volcanoes on Climate.- 5.4 Studies of Anthropogenic Alterations of the Stratospheric Aerosol Layer.- 5.5 Summary.- References.