The Remote Sensing of Tropospheric Composition from Space (eBook)

The Remote Sensing of Tropospheric Composition from Space 3
Preface 5
Acknowledgements 7
Contents 9
Contributors 19
List of Tables 23
List of Figures 25
Chemical Names and Molecular Formulae 31
Chapter 1: Tropospheric Remote Sensing from Space 33
1.1 Remote Sensing and the Scope of the Book 33
1.2 Earth Observation and Remote Sensing 35
1.3 Atmospheric Remote Sensing from Space 37
1.3.1 Pre-Satellite Days 37
1.3.2 Some Historical Milestones in Satellite Remote Sensing 38
1.3.3 Tropospheric Remote Sensing Using Back-Scattered Solar Radiation 39
1.3.4 Remote Sensing Using Thermal Infrared in the Troposphere 41
1.3.5 TROPOSAT and AT2 42
1.4 The Atmosphere, Tropospheric Chemistry and Air Pollution 43
1.4.1 The Physical Structure of the Atmosphere 43
1.4.2 Tropospheric Chemistry 45
a Free Radical Reactions in the Troposphere 46
b Stable Species in the Troposphere 48
1.4.3 Air Pollution and Environmental Policy 49
1.4.4 Environmental Issues of Relevance to the Troposphere 51
a Global Increase of Tropospheric Ozone and the Effect on Air Quality 51
b The Transport and Transformation of Pollutants 52
c Biomass Burning and Fire 52
d Persistent Organic Pollutants 53
e Acid Deposition 53
f Global Climate Change 54
g Stratospheric Ozone Depletion and Its Impact on the Troposphere 54
1.5 Measuring Atmospheric Composition 56
1.5.1 Long Term Observations 56
1.5.2 Regional and Episodic Studies 57
1.5.3 Investigation of Fast In Situ Photochemistry 57
1.5.4 In Situ Observational Techniques 57
1.5.5 Remote Sensing Versus In Situ Techniques 58
1.5.6 The Need for Global Tropospheric Measurements from Space 59
1.6 Electromagnetic Radiation and Molecular Energy Levels 60
1.6.1 Electromagnetic Radiation 60
a Scattering and Absorption of Radiation 61
b Spontaneous Emission, Stimulated Absorption and Emission 62
c Raman Scattering 62
1.6.2 Molecular Energy States 63
a Rotational Energy Levels and Transitions 63
Selection Rules for Rotational Transitions 64
b Vibrational Energy Levels and Transitions 64
c Electronic Energy States and Transitions 66
d The Populations of Molecular Energy States 66
1.7 Molecular Spectra and Line Broadening 67
1.7.1 Line Broadening Mechanisms and the Width of Absorption Lines 68
1.7.2 The Natural Linewidth 69
1.7.3 Pressure Broadening (Collisional Broadening) 69
1.7.4 Doppler Broadening 70
1.7.5 Atmospheric Spectral Line Shapes in Different Spectral Ranges 71
1.8 Spectroscopic Techniques for Chemical Analysis 72
1.8.1 Absorption Spectroscopy 72
1.8.2 Emission Spectroscopy 74
1.9 Atmospheric Scattering and Radiation Transfer 74
1.9.1 Scattering 75
a Rayleigh Scattering 75
b Raman Scattering 76
c Mie Scattering 76
d Total Scattering 77
1.9.2 Atmospheric Radiative Transfer 78
1.10 Remote Sensing: Images and Spectroscopy 81
1.10.1 Satellite Images 81
1.10.2 Spectroscopic Techniques in Remote Sensing 82
a Microwave Spectroscopy 83
b IR Spectroscopy 84
c UV/Visible/Short-Wave IR Absorption Spectroscopy 85
1.10.3 Passive and Active Remote Sensing 85
1.10.4 Nadir, Limb and Occultation Views 85
a Nadir view 85
b Multiple Views 86
c Limb Mode 87
d Occultation 87
1.10.5 Active Techniques 88
a Differential Absorption Lidar (DIAL) 89
1.11 Satellite Orbits 90
1.11.1 Low Earth Orbits (LEO) 90
1.11.2 Geostationary Orbits (GEO) 91
1.12 Summary 93
References 93
Chapter 2: The Use of UV, Visible and Near IR Solar Back Scattered Radiation to Determine Trace Gases 98
2.1 Basics and Historical Background 98
2.1.1 Satellite Observations in the UV/vis/NIR Spectral Range 101
2.1.2 Spectral Retrieval and Radiative Transfer Modelling 104
2.2 Spectral Retrieval 105
2.2.1 Discrete Wavelength Techniques 107
a Initial Intensity I0 107
b Separating Different Effects 107
c The Light Path 108
2.2.2 DOAS Type Retrievals 109
2.2.3 Some Considerations for DOAS Retrievals 111
a Fraunhofer Spectrum 111
b The Ring Effect 112
c Choice of Fitting Window 113
d Effects of Spectral Surface Reflectivity 114
2.2.4 Advanced DOAS Concepts 114
2.3 Interpretation of the Observations Using Radiative Transfer Modelling 117
2.3.1 Relevant Interaction Processes Between Radiation and Matter 117
a Molecular Scattering 117
b Particle Scattering 119
c Reflection and Absorption at the Surface 120
d Interactions at the Ocean Surface 120
e Molecular Absorption Processes 121
2.3.2 Quantities Used for the Characterisation of the Measurement Sensitivity 122
a The Total AMF 122
b Box-AMF and Weighting Functions 123
c Averaging Kernels 126
d 2-D and 3-D Box-AMF 128
2.3.3 Important Input Data 129
2.3.4 Overview of Existing Radiative Transfer Models 130
2.4 Separation of Tropospheric and Stratospheric Signals 132
2.4.1 Stratospheric Measurement Methods 133
2.4.2 Residual Methods 134
2.4.3 Model Method 134
2.4.4 Cloud Slicing method 135
2.4.5 Other Possible Approaches 135
2.5 Uncertainties in UV/vis/NIR Satellite Measurements 136
2.5.1 Instrument Noise and Stray Light 137
2.5.2 Spectroscopic Uncertainties and Instrument Slit Width 138
2.5.3 Spectral Interference 138
2.5.4 Light Path Uncertainties 139
2.5.5 Uncertainty of Separation Between Stratosphere and Troposphere 140
2.6 Synopsis of the Historic, and Existing, Instruments and Data Products 141
2.7 Example of the Retrieval Process 142
2.8 Future Developments 144
2.8.1 Technical Design 144
2.8.2 Data Analysis 146
2.8.3 Synergistic Use of Complementary Satellite Observations 146
References 147
Chapter 3: Using Thermal Infrared Absorption and Emission to Determine Trace Gases 153
3.1 Physical Principles 153
3.2 Thermal Infrared Instruments: Techniques, History, Specificity 157
3.2.1 Techniques 157
a Cell Correlation Radiometry 157
b Fourier Transform Spectroscopy 157
c Grating Spectrometry 158
3.2.2 History 158
3.2.3 Specificity 159
a Retrieval Algorithms/Inversions 160
b Forward Radiative Transfer 160
c The Optimal Estimation (OE) Formalism 161
i Finding an Optimal Solution 161
ii Information Content 161
iii Error Budget 162
d The Tikhonov-Philips Regularization 163
e Neural Networks 163
3.3 Thermal Infrared: Missions and Products 165
3.4 Examples 165
3.4.1 Limb and Solar Occultation Instruments 165
a ACE-FTS 165
b MIPAS 168
c HIRDLS 170
3.4.2 Nadir Looking Instruments 171
a IMG 171
b MOPITT 171
c AIRS 172
d TES 173
e IASI 174
3.5 Future Plans for Tropospheric Sounders 175
References 177
Chapter 4: Microwave Absorption, Emission and Scattering: Trace Gases and Meteorological Parameters 182
4.1 Introduction 182
4.2 Atmospheric Remote Sensing in the Microwave range 183
4.2.1 Vector and Scalar Radiative Transfer 183
4.2.2 Gas Absorption in the Microwave Region 185
4.2.3 Particle Extinction in the Microwave Region 186
4.2.4 Simulation Software 187
4.2.5 The Inverse Problem 189
4.2.6 Observing Technique 191
4.3 Temperature and Water Vapour Profiles 193
4.3.1 Introduction 193
4.3.2 Examples 195
4.4 Remote Sensing of Clouds and precipitation 196
4.4.1 Introduction 196
4.4.2 Retrieval of Cloud Liquid Water 199
4.4.3 Retrieval of Cloud Ice Water 201
4.4.4 Precipitation 203
4.5 Applications of Microwave Data in Operational Meteorology 206
4.5.1 Data Assimilation 206
4.5.2 Microwave Data in Operational Meteorology 206
4.5.3 Microwave Radiative Transfer Modelling in Data Assimilation 208
4.5.4 Impact of Remote Sensing Data on NWP 210
4.5.5 Conclusions 213
4.6 Microwave Limb Sounding of the Troposphere 215
4.6.1 Background to Microwave Limb Sounding of the Troposphere 215
4.6.2 Previous, Existing and Planned Microwave Limb Sounding Instruments 216
4.6.3 Applications of Microwave Limb Sounding of the Troposphere 217
4.6.4 Upper Tropospheric Composition and Chemistry 220
4.6.5 Conclusions 222
4.7 Active Techniques 224
4.7.1 Introduction 224
4.7.2 The CloudSat Radar 225
4.7.3 The CloudSat Mission 225
4.7.4 The Cloud Profiling Radar 226
4.7.5 The Tropical Rainfall Measurement Mission 227
4.7.6 Results from TRMM 229
4.7.7 Conclusions 232
4.8 Measuring Atmospheric Parameters Using the Global Positioning System 233
4.8.1 GPS Radio Occultation 233
4.8.2 Data Availability and Impact 234
4.8.3 Ground-Based GPS Observations 236
4.8.4 Impact Studies 239
4.9 Outlook 240
4.10 Tables of Microwave Sensors 242
References 244
Chapter 5: Remote Sensing of Terrestrial Clouds from Space using Backscattering and Thermal Emission Techniques 260
5.1 Introduction 260
5.2 Cloud Parameters and Their Retrievals 261
5.2.1 Cloud Cover 262
5.2.2 Cloud Phase 264
5.2.3 Cloud Optical Thickness 266
5.2.4 Effective Radius 268
5.2.5 Cloud Liquid Water and Ice Path 272
5.2.6 Cloud Top Height 273
5.3 Validation of Satellite Cloud Products 276
5.4 Modern Trends in Optical Cloud Remote Sensing from Space 278
5.4.1 Hyperspectral Remote Sensing 278
5.4.2 Lidar Remote Sensing 280
5.4.3 Future Missions 281
5.5 Conclusions 283
References 283
Chapter 6: Retrieval of Aerosol Properties 287
6.1 Introduction 287
6.2 Aerosol Retrieval Algorithms 292
6.3 Aerosol Optical Parameters 294
6.4 Databases for Aerosol Properties 297
6.5 Instruments Used for the Retrieval of Aerosol Properties from Space 298
6.6 Retrieval of Aerosol and Cloud Parameters from CALIPSO Observations 299
6.6.1 The CALIPSO Science Payload 300
6.6.2 CALIOP Data Calibration 301
6.6.3 Description of Available Data Products from CALIOP 302
6.6.4 CALIOP Retrieval Procedure for the Extinction Coefficient 303
6.7 Aerosol Remote Sensing from POLDER 304
6.7.1 POLDER Remote Sensing of Aerosols Over Ocean Surfaces 305
6.7.2 POLDER Remote Sensing of Aerosols Over Land Surfaces 306
6.8 Retrieval of Aerosol Properties Using AATSR 307
6.8.1 AATSR Characteristics 308
6.8.2 AATSR Retrieval Algorithm 308
6.8.3 AATSR Products 309
6.9 Aerosol Remote Sensing from Aqua/MODIS 311
6.9.1 MODIS Remote Sensing of Aerosols Over Ocean Surfaces 311
6.9.2 MODIS Remote Sensing of Aerosols Over Land 312
6.10 Aerosol Properties from OMI 312
6.10.1 Properties from OMI Using the Multi-Wavelength Algorithm 315
6.10.2 Status of the OMAERO Product 316
6.11 Retrieval of Aerosol Properties Using MERIS 317
6.12 Validation 320
6.13 Air Quality: Using AOD to Monitor PM2.5 in the Netherlands 320
6.13.1 Establishing an AOD-PM2.5 Relationship 322
6.13.2 Application of the AOD-PM2.5 Relationship to MODIS Data 324
6.14 Application to Climate: Aerosol Direct Radiative Forcing 325
6.14.1 Uncertainties in Aerosol Direct Radiative Forcing 327
6.14.2 Comparisons of Aerosol Radiative Forcing with Models 328
6.14.3 Aerosol Radiative Forcing: Conclusions 329
6.15 Use of Satellites for Aerosol-Cloud Interaction Studies 329
a SEVIRI 330
b PARASOL 330
c MODIS 330
d OMI 331
e CALIPSO 331
6.16 Intercomparison of Aerosol Retrieval Products 331
6.17 Conclusions 332
References 334
Chapter 7: Data Quality and Validation of Satellite Measurements of Tropospheric Composition 342
7.1 Introduction 342
7.2 Methods of Validation 346
7.2.1 Definitions 346
7.2.2 Comparing Data Sets 347
a Finding Collocated Data 347
b Selection and Filtering 348
c Data Treatment 349
Vertical Representation 349
Time Differences 350
Horizontal Representation 350
Noise Reduction 352
d Analysing the Data 352
7.2.3 Use of Models 355
7.2.4 Data Variability 356
7.3 Quality Assurance 357
7.3.1 Validation and Mission Planning 358
7.3.2 Calibration 358
a Viewing Geometry 358
b Wavelength 359
c Absolute Radiance 359
7.3.3 Lower-Level Data Products 359
7.3.4 Retrieval Algorithm Optimisation 360
7.3.5 Instrument Degradation 360
7.3.6 Overall Quality Monitoring 361
7.4 Validation Characteristics of Tropospheric Products 362
7.4.1 Tropospheric Processes Impacting on Trace Gas Distributions 363
7.4.2 Validation Needs for Trace Gases with Stratospheric Contributions 365
a What Causes Stratospheric Variability? 365
b What Determines the Vertical Distribution of these Species? 367
7.4.3 Validation Needs Related to Cloud, Albedo and Aerosol Effects 368
7.4.4 Validation Needs for Aerosols 370
7.5 The Use of Correlative Measurements for Validation 371
7.5.1 In Situ Measurements 371
a In Situ Measurements for O3 and CO 373
b In Situ Measurement Techniques for NO2 375
c Factors Impacting on the Use of In Situ Measurements for Satellite NO2 Data Validation 376
7.5.2 Remote Sensing 376
a Multi-Axis Differential Optical Absorption Spectroscopy (MAXDOAS) 377
b Fourier Transform Infrared Spectroscopy (FTIR) 379
c Light Detection and Ranging (lidar) 379
d Sun Photometers 380
7.5.3 Networks and Data Centres 380
7.5.4 Validation Activities 381
7.6 Future Validation strategies 381
7.6.1 Requirements for Future Validation Measurements 381
7.6.2 Validation Strategy for Tropospheric O3 382
7.6.3 Validation Strategy for Tropospheric NO2 382
7.6.4 Validation Strategy for CO 384
References 384
Chapter 8: Applications of Satellite Observations of Tropospheric Composition 392
8.1 Introduction 392
8.2 Overview of the Tropospheric Chemical Species Measured from Space 393
8.2.1 Tropospheric Ozone, O3 393
8.2.2 Nitrogen Dioxide, NO2 395
8.2.3 Carbon Monoxide, CO 398
a General Transport Phenomena 400
b Hemispheric Transport of Air Pollution 401
c Emission Estimates 402
d Fires (Biomass Burning) 403
e Model Performance 404
8.2.4 Formaldehyde, HCHO 405
8.2.5 Glyoxal, CHOCHO 406
8.2.6 Sulfur Dioxide, SO2 407
8.2.7 Ammonia, NH3 409
8.2.8 Carbon Dioxide, CO2 409
8.2.9 Methane, CH4 411
8.2.10 Water, H2O 412
8.2.11 Bromine Monoxide, BrO 413
8.2.12 Iodine Monoxide, IO 415
8.2.13 Methanol, CH3OH 416
8.2.14 Nitrous Oxide, N2O 417
8.2.15 Nitric Acid, HNO3 418
8.2.16 Other Trace Species 418
8.3 Satellite Observations of Tropospheric Composition: What Can We Learn? 426
8.3.1 Column Density Maps as Proxies for Emissions 426
8.3.2 Monitoring Transport and Circulation 431
8.3.3 Trends 434
8.3.4 Periodical Temporal Patterns 437
8.3.5 Synergistic Use of Different Measurements 438
a Improving Retrievals 439
b Identifying Sources 439
c Learning About Atmospheric Chemistry 440
d Learning About Profiles 440
e Multi-Platform Observations 441
8.3.6 Operational Use 443
8.4 Summary and Outlook 444
References 445
Chapter 9: Synergistic Use of Retrieved Trace Constituent Distributions and Numerical Modelling 477
9.1 Introduction 477
9.2 Use of Satellite Data for Process Understanding and Model Evaluation 480
9.2.1 Understanding Atmospheric Chemistry 481
a Formaldehyde, HCHO: A Proxy for VOC Emissions 482
b Glyoxal, CHOCHO: Source Apportionment 483
c Determining Dominant Chemical Pathways: Air Pollution Impact 485
d Understanding Differences Between Retrievals and Model Results 486
9.2.2 Model Evaluations - Comparison with Observation 487
a NO2 488
b CO 490
c Aerosol 492
9.3 Inverse Modelling 493
9.3.1 Inversions for Short-Lived Species 493
9.3.2 Inversions for CO and CH4 497
9.3.3 Need for Future Developments 498
9.4 Data Assimilation 499
9.4.1 Objectives and State of the Art Approaches 499
9.4.2 Example Results for Tropospheric O3 assimilation 501
9.4.3 Example Results for NO2 Tropospheric Column Assimilation 502
9.4.4 Aerosol Satellite Data Assimilation 504
9.5 Summary: Perspectives 507
9.6 Appendix 508
Inverse Modelling: Principles 508
References 511
Chapter 10: Conclusions and Perspectives 519
10.1 Introduction: The Need for Satellite Observations 519
10.2 Some Scientific Highlights 521
10.2.1 Observed Compounds 521
10.2.2 The Multiple Roles of NO2 522
10.2.3 Industrial Emissions and Biomass Burning 522
10.2.4 Ozone, O3 523
10.2.5 Greenhouse Gases 523
10.2.6 Water Vapour, and Other Hydrological and Cloud Parameters 524
10.2.7 Aerosol and Cloud Parameters 524
10.2.8 Volcanic Emissions 526
10.3 Scientific Needs 526
10.4 Further Interpretation of Data from Current Instrumentation 528
10.4.1 Retrieval Algorithm Developments 528
10.4.2 The Use of Multiple Observations 529
10.4.3 Data Assimilation 529
10.5 Idealised Requirements for the Evolution of Instrumentation 530
10.6 Perspectives for the Improvement of Instrument Technology 531
10.6.1 Polarisation Measurements 531
10.6.2 Measurements for Tomographic Reconstruction 532
10.6.3 Multi-Wavelength Hyper-Spectral Measurements 532
10.6.4 Multi-Instrument Measurements 532
10.6.5 Microwave and Sub-mm Spectral Region 532
10.6.6 Active Systems 532
10.7 Current and Future Planned Missions 533
10.7.1 LEO Satellite Instruments 533
10.7.2 GEO Satellite Instruments 534
10.7.3 Greenhouse Gases 535
10.7.4 Observations from the Lagrange Point 536
10.8 Future Monitoring of the Troposphere from Space 536
10.9 Conclusions 538
References 539
Appendices 541
Appendix A: Satellite Instruments for the Remote Sensing in the UV, Visible and IR 541
Abbreviations Used in the Table 541
Appendix B: Atlas of Ancillary Global Data 548
Appendix C: Abbreviations and Acronyms 550
Appendix D: Timelines for Present and Future Missions 558
D.1Tropospheric Reactive Gases 558
D.2Greenhouse Gases: CH4, CO2 560
D.3Greenhouse Gases: Water Vapour 561
D.4Tropospheric Aerosol 562
D.5Clouds 563
Index 565