Contents

List of Contributors xiii

1 A Climatology of UV Radiation, 1979 - 2000, 65S - 65N 1

1.1 Introduction 1

1.2 Method 2

1.3 Results 6

1.3.1 Satellite-Derived UV Climatologies 6

1.3.2 Comparison with Ground-Based Measurements 14

1.3.3 Discussion of Uncertanties 16

1.4 Conclusions 17

Acknowledgements 17

References 18

2 Balancing the Risks and Benefits of Ultraviolet Radiation 21

2.1 Introduction 22

2.2 Long Term Changes in UVEry 22

2.3 Geographical Variability in UVEiy 23

2.4 Peak UV 24

2.4.1 Peak UV Index 24

2.4.2 Peak UV Daily Dose 28

2.5 Comparing Weighting Functions for Erythema and Vitamin D 29

2.6 Seasonal and Diurnal Variation of UVEry and UVVitD 31

2.7 Global Climatologies of UVEry and UVVitD 33

2.8 Relationship Between UVVitD and UVEry 36

2.9 Production of Vitamin D from Sunlight 38

2.10 Calculation of Optimal Times for Exposure to Sunlight 38

2.11 An Inconsistency 42

2.12 Conclusions 44

Acknowledgements 45

References 45

3 Climatology of Ultraviolet Radiation at High Latitudes Derived from Measurements of the National Science Foundation's Ultraviolet Spectral Irradiance Monitoring Network 48

3.1 Introduction 49

3.2 Data Analysis 51

3.2.2 Establishment of Climatologies 52

3.2.3 Estimates of Historical UV Indices 52

3.3 UV Index Climatology 56

3.3.1 South Pole 56

3.3.2 McMurdo Station 57

3.3.3 Palmer Station 59

3.3.4 Ushuaia 60

3.3.5 San Diego 60

3.3.6 Barrow 61

3.4 Climatology of UV-A Irradiance 62

3.5 Comparison of Radiation Levels at Network Sites 65

3.6 Conclusions and Outlook 69

Acknowledgements 70

References 70

4 UV Solar Radiation in Polar Regions: Consequences for the Environment and Human Health 73

4.1 Introduction 74

4.2 Networks and Databanks 76

4.3 Impact of Solar UV on the Environment 79

4.3.1 Effect of the Environment on Solar UV 85

4.4 Impact of Solar UV on Human Health 88

4.4.1 Information and Protection Programs 92

4.4.2 Dosimetry, UV Modeling, and Instruments 93

4.5 Concluding Remarks 98

References 99

5 Changes in Ultraviolet and Visible Solar Irradiance 1979 to 2008 106

5.1 Introduction 106

5.2 Instrumentation 112

5.3 Detection of Long-Term Change 121

5.3.1 Radiation Amplification Factor 122

5.3.2 Different Definitions of RAF 125

5.3.3 Estimating UV Trends: Discussion 126

5.3.4 Reduction of UV Irradiance by Clouds and Aerosols 128

5.3.5 Stokes Derivation of CT = (1 - R)/(1 - RG) 130

5.3.6 UV Absorption 132

5.3.7 Estimating Zonal Average UV Change 132

5.3.8 Estimating UV Trends: Satellites 133

5.3.9 Estimating UV Trends: Ground-Based 138

5.4 UV in the Polar Regions 139

5.5 Human Exposure to UV 140

5.6 UV Index and Units 143

5.7 Action Spectra and Irradiance Trends 143

5.8 UV Summary 151

Appendix 5.1 Calculating RAF(#) 153

Acknowledgements 155

References 155

6 The Brewer Spectrophotometer 160

6.1 Introduction 160

6.2 History 161

6.3 The Instrument 163

6.3.1 The Fore-Optics 165

6.3.2 The Spectrometer 166

6.3.3 The Photomultiplier Housing 168

6.3.4 Support Electronics 169

6.3.5 The Control Computer 170

6.4 Corrections Applied to Data 170

6.4.1 Dark Count 170

6.4.2 Dead Time 171

6.4.3 Stray Light 172

6.4.4 Temperature Response 172

6.4.5 Neutral Density Filters 173

6.4.6 Cosine Response 173

6.4.7 Internal Polarization 174

6.5 Measurement of Total Ozone 175

6.5.1 Measurement Technique 175

6.5.2 Calibration 177

6.6 Measurement of Spectral UV Radiation 179

6.7 Measurement of Other Atmospheric Variables 181

6.7.1 Vertical Profile of Ozone 182

6.7.2 Atmospheric SO2 182

6.7.3 Atmospheric NO2 183

6.7.4 Aerosol Optical Depth 183

6.7.5 Effective Temperature of Atmospheric Ozone 184

6.8 The Brewer Spectrophotometer as a Powerful Research Tool 185

6.9 Summary 186

Acknowledgements 186

References 186

7 Techniques for Solar Dosimetry in Different Environments 192

7.1 Introduction 192

7.2 UV Dosimetry and Minimization Strategies 194

7.3 Miniaturization of Polysulphone Dosimeters 195

7.4 Measurements on Plants 197

7.5 Long-Term UV Dosimeters 199

7.6 Vitamin D Effective UV Dosimetry 200

7.7 Discussion and Conclusions 201

References 202

8 An Ultraviolet Radiation Monitoring and Research Program for Agriculture 205

8.1 Introduction 206

8.2 Introduction to the USDA UVMRP (Purpose and History) 207

8.3 Monitoring Network 208

8.3.1 Sites and Coverage 208

8.3.2 Data Products Provided by UVMRP 209

8.4 Data Collection and Processing 210

8.4.1 UV-MFRSR Data Processing 212

8.4.2 Erythemally Weighted UV Irradiance 215

8.4.3 Langley Analysis 219

8.4.4 Data Processing for Other Measurements 221

8.5 Derived Products 222

8.5.1 Optical Depth 223

8.5.2 Daily Column Ozone 224

8.5.3 Synthetic Spectrum Data 225

8.6 Database Design and Website Interface 227

8.6.1 The Data 227

8.7 UVMRP's Role in UV-B Agricultural Effects Studies 229

8.7.1 Mississippi State University 230

8.7.2 Purdue University 230

8.7.3 Utah State University 231

8.7.4 University of Maryland 231

8.7.5 Washington State University 231

8.7.6 University of Illinois—Chicago 232

8.7.7 Highlights of Other Collaborations 232

8.8 Modeling of Agricultural Sustainability 233

8.9 Future Considerations 234

8.10 Summary 235

Acknowledgements 237

References 237

9 Radiative Transfer in the Coupled Atmosphere-Snow-Ice-Ocean (CASIO) System: Review of Modeling Capabilities 244

9.1 Introduction 245

9.2 Radiative Transfer Modeling 247

9.2.1 Sun-Earth Geometry 247

9.2.2 Spectrum of Solar Radiation 248

9.2.3 Atmospheric Vertical Structure 249

9.2.4 Light Interaction with Absorbing and Scattering Media 250

9.2.5 Equation of Radiative Transfer 256

9.2.6 Surface Reflection and Transmission 257

9.2.7 Radiative Transfer in a Coupled Atmosphere-Snow-Ice-Ocean (CASIO) System 258

9.3 Sample Applications of the Theory 259

9.3.1 Comparison of Modeled Irradiances in CAO Systems 259

9.3.2 Measured and Modeled Radiation Fields in Sea Ice 261

9.3.3 Radiation Trapping in Sea Ice 261

9.3.4 Impact of Ozone Depletion on Primary Productivity 263

9.4 Discussion and Conclusions 264

Acknowledgements 265

References 265

10 Comparative Analysis of UV-B Exposure Between Nimbus 7/TOMS Satellite Estimates and Ground-Based Measurements 270

10.1 Introduction 271

10.2 Materials and Methods 274

10.2.1 USDA UV-B Dataset 274

10.2.2 TOMS Dataset 274

10.2.3 UV Index 276

10.2.4 Comparative Analysis 276

10.3 Results and Discussion 277

10.3.1 UV-I Daily Change Analysis 277

10.3.2 Analysis of UV-I Variability 279

10.3.3 UV-I Spatial Analysis 281

10.4 Conclusions 287

Acknowledgements 289

References 289

11 Ultraviolet Radiation and Its Interaction with Air Pollution 291

11.1 Introduction 291

11.1.1 Factors Affecting UV Flux at the Earth's Surface 292

11.2 Optics of the Atmosphere 301

11.2.1 Scattering 301

11.2.2 Absorption 303

11.2.3 Emission 304

11.2.4 Atmospheric Optical Depth 304

11.2.5 Single Scatter Albedo 309

11.2.6 Asymmetry Factor 310

11.2.7 Angstrom's Exponent 310

11.3 Models and Measurements 310

11.4 Summary 325

References 326

12 Urban Forest Influences on Exposure to UV Radiation and Potential Consequences for Human Health 331

12.1 Introduction 332

12.2 Effects of Solar UV on Human Health and Epidemiology 333

12.2.1 Sunburn 333

12.2.2 Skin Types 336

12.2.3 Immune Function 336

12.2.4 Skin Cancers 336

12.2.5 Eye Diseases 339

12.2.6 Sunscreen Effectiveness 339

12.2.7 Positive Impacts 339

12.3 UV Climatology 344

12.3.1 Ozone Trends 344

12.4 Urban Structural Influences 346

12.4.1 Sky Radiance and Diffuse Fraction 346

12.4.2 UV Reflectivity 347

12.4.3 Tree and Building Influences on UV 347

12.4.4 Human Exposure 356

12.5 Public Health Information 357

12.6 Conclusions 358

Acknowledgements 359

References 360

13 Solar UV-B Radiation and Global Dimming: Effects on Plant Growth and UV-Shielding 370

13.1 Introduction 371

13.1.1 Global Dimming and UV-B: Potential Effects on

Plants 371

13.1.2 Assessing Global Dimming and UV-B Effects on

Plant Growth 372

13.2 Methods 374

13.2.1 Field Site 374

13.2.2 Structural and Biomass Measurements 375

13.2.3 UV-A Epidermal Transmittance Measurements 376

13.2.4 Solar UV and PAR Irradiance 376

13.2.5 Statistical Analyses 377

13.3 Results 377

13.3.1 UV-A Epidermal Transmittance 377

13.3.2 Dimming Effects on Biomass and Structure 381

13.4 Discussion 383

13.4.1 Global Dimming and UV-B Effects on Leaf Optical Properties 384

13.4.2 Global Dimming and UV-B Effects on Productivity 384

13.4.3 Ecological Implications 385

13.5 Concluding Remarks 388

Acknowledgements 389

References 389

14 Effects of Ultraviolet-B Radiation and Its Interactions with Climate Change Factors on Agricultural Crop Growth and Yield 395

14.1 Introduction 396

14.2 Abiotic Stress Factors and Crop Yield 400

14.3 Crop Responses to UV-B and Other Climate Change Factors 401

14.3.1 Specific Effects of UV-B Radiation on Plants 402

14.3.2 Strategies for Protection against UV-B Radiation 410

14.3.3 Crop Response to Atmospheric CO2 Concentration 412

14.3.4 Crop Response to Temperature 413

14.3.5 Crop Response to Drought 414

14.3.6 Crop Response to Multiple Abiotic Stress Factors 416

14.4 Abiotic Stress Tolerance and Cultivar Screening Tools 419

14.5 Climate Change and Aerobiology and Public Health 422

14.6 Concluding Remarks 423

Acknowledgements 424

References 424

15 Assessment of DNA Damage as a Tool to Measure UV-B Tolerance in Soybean Lines Differing in Foliar Flavonoid Composition 437

15.1 Introduction 438

15.2 Materials and Methods 441

15.2.1 Plant Growth and UV Irradiation 441

15.2.2 Field Sampling 442

15.2.3 Analysis of Phenolics 443

15.2.4 Determination of DNA Lesions—Gel

Electrophoresis Method 443

15.2.5 Determination of DNA Lesions—Monoclonal

Antibody Method 446

15.2.6 Experimental Design and Statistical Analysis 446

15.3 Results and Discussion 446

15.3.1 Leaf Phenolics 446

15.3.2 DNA Damage 448

15.4 Conclusions 452

Acknowledgements 453

References 453

16 Physiological Impacts of Short-Term UV Irradiance Exposures on Cultivars of Glycine Max 458

16.1 Introduction 459

16.2 Materials and Methods 461

16.2.1 Plant Material and Greenhouse Growth Conditions 461

16.2.2 UV Treatment 462

16.2.3 UV Exposure Regimes 463

16.2.4 Stomatal Conductance Measurements 466

16.2.5 Photosynthesis and Transpiration Measurements 467

16.2.6 Pigment Analyses 467

16.2.7 UV-B Absorbing Compounds 468

16.3 Results and Discussion 469

16.3.1 Stomatal Conductance 469

16.3.2 Transpiration 473

16.3.3 Photosynthesis 476

16.3.4 Water Use Efficiency 478

16.3.5 UV-B Absorbing Compounds and Leaf Pigments 478

16.4 Summary and Conclusions 481

Acknowledgements 483

References 483

17 UV-Effects on Young Seedlings of Soybean: Effects in Early Development and Long-Term Effects 488

17.1 Introduction 488

Main Objectives 492

17.2 Results and Discussion 492

17.2.1 UV Effects on Early Development and Survival of

Young Soybean 492

17.2.2 Surviving Soybean: the Affect on Seed Production 496

17.2.3 Assessment of Phenylpropanoids in Response to UV 498

17.3 Conclusions 499

17.4 Methods 500

17.4.1 Plant Materials and Accessions 500

17.4.2 Plant Growth and Preparation of Tissue 500

17.4.3 Chemicals 501

17.4.4 UV Radiation Sources and Treatments 501

17.4.5 Metabolome Studies 501

Acknowledgements 502

References 502

18 Characteristics of UV-B Radiation Tolerance in Broadleaf Trees in

Southern USA 509

18.1 Introduction 510

18.2 Methodology 514

18.2.1 Plant Materials 514

18.2.2 Measuring Leaf Optical Properties 514

18.2.3 Measuring the Light Penetration and Distribution within Leaf Tissues 515

18.2.4 Scanning Electron Microscopy and Light Microscopy of Leaves 517

18.2.5 Measurements of UV-B Absorbing Compounds and Chlorophyll Concentrations 517

18.2.6 Statistical Analysis 518

18.3 Results and Discussion 518

18.3.1 Leaf Optical Properties 518

18.3.2 Depth of Light Penetration into Leaf Tissues 519

18.3.3 The Concentration of Leaf UV-B Absorbing Compounds 522

18.3.4 Correlations among the UV-B Related Variables within and among the Species 524

18.4 Conclusions 527

Acknowledgements 527

References 528

Index 531

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