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TITLE
CERTIFICATE
DECLARATION
ACKNOWLEDGEMENT
CONTENTS
Preface
1. AN INTRODUCTION TO ATMOSPHERIC AEROSOL SYSTEM
1.1 Introduction
1.2 Sources of Aerosols
1.3 Aerosol Production Mechanisms
1.3.1 Bulk-to-Particle Conversion
1.3.2 Gas-to-Particle Conversion
1.4 Aerosol Removal Mechanisms
1.4.1 Coagulation
1.4.2 Dry deposition
1.4.3 Wet Removal
1.5 Aerosol Transport Mechanisms
1.6 Residence Time of Atmospheric Aerosols
Table (1.1) Residence Time of Atmospheric Aerosol Particles
1.7 Aerosol Continuity Equation
1.8 Aerosol Size Distributions
1.9 Chemical Composition of Aerosols
1.10 Optical Effects of Aerosols
1.11 Aerosol Optical Parameters
1.11.1 Aerosol Scattering and Extinction Coefficients
1.11.2 Aerosol Scattering Phase Function
1.11.3 Single Scattering Albedo and Asymmetry Factor
1.11.4 Upscatter Fraction
1.11.5 Optical Depth
1.12 Experiment Techniques for Aerosol Measurements
1.12.1 Aerosol Remote Sensing Techniques
1.12.1.1 Passive Remote Sensing
1.12.1.2 Active Remote Sensing
1.12.2 Aerosol In situ Measurements
1.13 Analytical Techniques for Aerosol Particle Speciation
1.14 A Brief Survey of Aerosol Size Distribution and Altitude Structure Studies in the Boundary Layer
2. EXPERIMENT SET UP, DATA AND METHOD OF ANALYSIS
2.1 introduction
2.2 Location of the Experiment Site
2.3 Andersen Low Pressure Impactor
2.3.1 Instrument Description and Assembly
Fig. (2.1) Schematic diagram of Andersen Low Pressure Impactor
2.3.2 Impactor Operation
Fig. (2.2) Flow calibration curve of Andersen Low Pressure Impactor
2.3.3 Theory of Impaction
Fig. (2.3) Schematic of impactor stage.
2.4 The Bistatic Continuous Wave Lidar
Table (2.2) Transmitting and Receiving System Parameters
2.4.1 The Transmitting System
2.4.1.1 Beam Alignment System
Plate I - Laser source and the transmitting optics (inside laboratory)
Plate II - Laser beam into the atmosphere (during lidar operation)
Fig. (2.4) Schematic of mirror system used for beam alignment.
2.4.2 The Receiving System
2.4.2.1 The Receiving Telescope
Fig. (2.5) Schematic diagram of receiving telescope
PlateIII Receiving Telescope
2.4.2.2 The Photomultiplier and Dynode Circuit
2.4.2.2.1 Current to Voltage Converter
Fig. (2.9) Current-to-voltage converter and low pass filter
2.4.2.3 Control and Data Acquisition System
2.4.2.3.1 Programmable Gain Instrumentation Amplifier
2.4.2.3.2 Gain Control and Data Acquisition Unit
Plate-1V Data Acquisition System
2.4.2.3.3 Data Acquisition Software
2.5 Operation of Bistatic Lidar System
2.6 Lidar Geometry
2.7 The Lidar Equation
2.7.1 Calculation of Scattering Volume
2.7.2 Altitude of the Scattering Volume and Altitude Resolution
2.8 Differential Angular Scattering Coefficients of Molecules and Aerosols
2.9 Atmospheric Transmittance and Optical Depth
3. SURFACE AEROSOL CHARACTERISTICS USING LOW PRESSURE IMPACTOR
3.1 Introduction
3.2 Estimation of Impactor Cut Points
3.3 Effect of Relative Humidity on Aerosol Size and Density
3.4 Estimation of Stokes Radius and Aerosol Size Distributions and Correction for Relative Humidity
3.5 Mass and Number Distributions of Near Surface Aerosols
3.6 Analytical Model of Aerosol Size Distributions
3.7 Characteristics of Aerosol Size Distributions
3.8 Seasonal Mean Size Distributions
3.9 Seasonal Variation of Aerosol Mass Concentration
3.10 Principal Components
3.11 Summary
4. ALTITUDE STRUCTURE OF AEROSOL NUMBER DENSITY AND ITS ASSOCIATION WITH BOUNDARY LAYER METEOROLOGICAL FEATURES
4.1 Introduction
4.2 Meteorological Conditions at the Experiment Site
4.3 Estimation of Aerosol Number Density from Lidar Data
4.3.1 Estimation of Lidar System Constant
4.3.2 Standard Error of Aerosol Number Density
4.4 Altitude Profiles of Aerosol Number Density
4.4.1 Monthly Mean Profiles of Aerosol Number Density
4.4.2 Seasonal Mean Profiles of Aerosol Number Density
4.4.3 Annual Mean Profiles of Aerosol Number Density
4.5 Aerosol Mixing Height and ABL Structure
4.5.1 influence of ABL Meteorological Features on the Altitude Structure of Aerosol Number Density
4.5.2 Estimation of Aerosol Mixing Height from Aerosol Number Density Profile
4.5.3 Aerosol Mixing Height and its Association with Vertical Mixing
4.5.4 Relative Contribution of Well-mixed Region to Mixing Region Aerosols
4.5.5 Ventilation Coefficient
4.6 Wind Speed Dependence of Aerosol Number Density in ABL
4.7 Seasonal Variation of Background and Wind Dependant Components
4.8 Summary
5. ANALYTICAL MODEL FOR THE ALTITUDE VARIATION OF AEROSOL NUMBER DENSITY IN THE MIXING REGION
5.1. Introduction
5.2 Analytical Model for Aerosol Number Density
5.3 Estimation of Model Parameters
5.4 Development of Analytical Model
5.5 Source Strength and its Variation
5.6 Summary
6. SEASONAL VARIATION AND LONG TERM TRENDS
6.1 Introduction
6.2 Aerosol Extinction Near the Surface
6.3 Mixing Region Aerosol Optical Depth from CW Lidar
6.4 Columnar Aerosol Optical Depth from Solar Radiometer
6.5 Seasonal and Annual Variations at Different Altitude Regions
6.6 Contribution of Mixing Region to Columnar aerosol Optical Depth
6.7 Long Term Trends
6.8 Summary
7. SUMMARY
List of Publications
References