Energy and Matter Fluxes of a Spruce Forest Ecosystem (eBook)

Thomas FokenUniversity of Bayreuth, Bayreuth Center of Ecology and Environmental Research (BayCEER), Bayreuth, Germany

Foreword 6
Preface 8
Contents 10
List of Abbreviations 13
Part I Introduction 16
1 History of the Waldstein Measuring Sites 17
1.1 Introduction 17
1.2 The Foundation of BITÖK and the Establishment of the Waldstein Sites 18
1.3 Research and Measuring Programs 19
1.3.1 BITÖK Research Projects 19
1.3.2 European Research Projects 24
1.3.3 German Research Projects 26
1.3.4 Permanent Measuring Program 26
1.4 Conclusions 28
Reports 29
References 29
2 Description of the Waldstein Measuring Site 33
2.1 Introduction 33
2.2 The Waldstein Area 36
2.3 Specific Details of the Measuring Sites 37
2.3.1 Waldstein-Weidenbrunnen 37
2.3.1.1 Forest Stand 37
2.3.1.2 Instrumentation 39
2.3.2 Waldstein-Pflanzgarten 44
2.3.3 Köhlerloh 47
2.4 Conclusions 49
References 50
Part II Studies of Long-Term Measurements 53
3 Climate, Air Pollutants, and Wet Deposition 54
3.1 Introduction 54
3.2 Material and Methods 56
3.2.1 Main Meteorological Elements and Climatological Observations 56
3.2.2 Air Pollution Measurements 57
3.2.3 Wet Deposition 58
3.3 Results and Discussion 60
3.3.1 Climatology 61
3.3.1.1 Air Temperature 62
3.3.1.2 Precipitation 65
3.3.2 Air Pollutants O3, SO2, and NOx 69
3.3.2.1 Ozone 69
3.3.2.2 Trend Analysis 69
3.3.2.3 Annual O3 Variation and the Accumulated Exposure Over a Threshold of 40 ppb (AOT) 71
3.3.2.4 SO2 and NOx 73
3.3.3 Fog Deposition Fluxes 75
3.3.4 Wet Deposition 77
3.4 Conclusions 83
References 84
4 Long-Term Carbon and Water Vapour Fluxes 86
4.1 Introduction 86
4.2 Methods 87
4.2.1 Site Description and Measurement Set-up 87
4.2.2 Data Processing 88
4.2.2.1 Turbulent Flux Processing 88
4.2.2.2 Meteorological Data 89
4.2.2.3 Gap-Filling 90
4.3 Results and Discussion 91
4.3.1 Energy Balance Closure of EC Measurements 91
4.3.2 Adaptations of the Gap-Filling Method for NEE 92
4.3.3 Carbon and Water Vapour Fluxes 93
4.3.3.1 Carbon Exchange 95
4.3.3.2 Water Vapour Fluxes 98
4.3.4 Factors Influencing the Carbon and Water Vapour Exchange 100
4.3.4.1 Development of the Spruce Forest at Waldstein Site 100
4.3.4.2 Instrumental and Methodological Issues 100
4.3.4.3 Influential Factors of Regional Relevance 102
4.4 Conclusion 104
References 106
Part III Experimental Studies of Energy and Matter Fluxes 110
5 Sap Flow Measurements 111
5.1 Introduction 111
5.2 Material and Methods 113
5.2.1 Study Sites 113
5.2.2 Sap Flow Measuring Technique 114
5.2.3 Modeling 114
5.2.4 Eddy Covariance Measurements 115
5.3 Results and Discussions 115
5.3.1 Tree Sap Flow and Canopy Transpiration 115
5.3.2 Tree Profile Measurements 119
5.4 Conclusions 121
References 122
6 Coherent Structures and Flux Coupling 125
6.1 Introduction 125
6.2 Materials and Methods 127
6.2.1 Detection Algorithm and Conditional Flux Computation 127
6.2.2 Adapted Experimental Setup 131
6.3 Results and Discussions 132
6.3.1 Exchange Regimes for Vertical Coupling 132
6.3.2 Exchange Regimes for Horizontal Coupling 136
6.3.3 Implementation for Quantifying Daytime Sub-canopy Respiration 138
6.3.4 Implications for Spatial Heterogeneity of Sub-canopy Carbon Dioxide Concentrations, Gradients, and Horizontal Advection 140
6.4 Conclusions 141
References 145
7 Dynamics of Water Flow in a Forest Soil: Visualization and Modelling 148
7.1 Introduction 148
7.2 Material and Methods 150
7.2.1 Measurements of Matric Potentials 150
7.2.2 Modelling Matric Potentials and Soil Water Fluxes 150
7.2.3 Comparison Between Measured and Modelled Matric Potentials 152
7.2.4 Visualizing Soil Water Fluxes 154
7.3 Results and Discussion 155
7.3.1 Matric Potential 155
7.3.1.1 Temporal Variability 155
7.3.1.2 Hydraulic Redistribution 158
7.3.1.3 Complexity of Measured and Modelled Matric Potentials 159
7.3.2 Soil Water Fluxes 161
7.3.2.1 Flow Patterns at Profile Scale and Their Influence on Soil Chemistry 161
7.3.2.2 Modelling Results and Preferential Flow at Catchment Scale 163
7.4 Conclusions 163
References 165
8 Trace Gas Exchange at the Forest Floor 168
8.1 Introduction 168
8.2 Materials and Methods 170
8.2.1 Site Description 170
8.2.1.1 Wind, Temperature, and Radiation Measurements 171
8.2.1.2 Trace Gas Measurements 171
8.2.2 Modelling of Fluxes Near the Forest Floor 172
8.2.2.1 Parameterization According to Richter and Skeib (1984, 1991) 173
8.2.2.2 Parameterization According to Foken (1979, 1984) 174
8.3 Results and Discussion 174
8.3.1 Driving Forces of Subcanopy Exchange 174
8.3.1.1 Radiation 174
8.3.1.2 Temperature Profiles 176
8.3.1.3 Wind Profiles 176
8.3.2 Comparison of Measured and Modelled Fluxes 176
8.3.2.1 Friction Velocity 176
8.3.2.2 Sensible Heat Flux 178
8.3.2.3 Stability 179
8.3.3 Comparison of Modelled and Chamber Fluxes 180
8.3.3.1 Radon Fluxes 180
8.3.3.2 Carbon Dioxide Fluxes 181
8.3.4 Determination of the Coupling Situation at the Forest Floor 182
8.3.4.1 Water Vapor 183
8.3.4.2 Carbon Dioxide 184
8.3.5 Reactive Trace Gases 184
8.3.5.1 Ozone Fluxes 186
8.4 Conclusions 187
References 188
9 Reactive Trace Gas and Aerosol Fluxes 191
9.1 Introduction 191
9.2 Materials and Methods 194
9.2.1 Trace Gas Flux Instrumentation 194
9.2.2 Aerosol Flux Instrumentation 197
9.3 Results and Discussion 199
9.3.1 Reactive Trace Gas Flux Measurements 199
9.3.1.1 Ozone Fluxes 200
9.3.1.2 NOx Fluxes 201
9.3.1.3 Fluxes of Additional Reactive Trace Gases 202
9.3.2 Aerosol Flux Measurements 207
9.3.2.1 Aerosol Number Fluxes 208
9.3.2.2 Size-Resolved Number Fluxes 208
9.3.2.3 Chemically Speciated Aerosol Fluxes 210
9.3.3 Comparison of Flux Observations and Models 211
9.4 Conclusions 214
References 215
10 Isotope Fluxes 219
10.1 Introduction 219
10.2 Materials and Methods 221
10.2.1 Balances of CO2 and 13CO2 221
10.2.2 NEE Partitioning and 13CO2 Iso-fluxes 222
10.2.3 Hyperbolic Relaxed Eddy Accumulation Method 225
10.2.4 HREA Measuring Systems 227
10.2.5 Measurement Sites and Campaigns 230
10.3 Results and Discussion 232
10.3.1 Differences in HREA Samples of CO2 and ?13C Up- and Downdrafts 232
10.3.2 CO2 Fluxes and 13CO2 Iso-fluxes 236
10.3.3 13CO2 Signatures and NEE Partitioning 240
10.3.4 Structure of CO2 Exchange Mechanisms over Forests 245
10.4 Conclusions 247
References 250
11 Influence of Low-Level Jets and Gravity Waves on Turbulent Fluxes 256
11.1 Introduction 256
11.2 Material and Methods 258
11.2.1 Experimental Setup 258
11.2.2 Instruments: Principles of Operation 260
11.2.2.1 Windprofiler/SODAR 260
11.2.2.2 RASS 261
11.2.3 Data Calculation 262
11.2.4 Meteorological Situation 263
11.3 Results and Discussion 267
11.3.1 Low-Level Jets 267
11.3.2 Gravity Waves 271
11.3.2.1 Rotary Spectrum 274
11.3.2.2 Hodograph Analysis 275
11.3.2.3 Stokes Parameter Spectra 276
11.3.2.4 Gravity Wave Characteristics 278
11.4 Conclusions 281
References 282
12 Development of Flux Data Quality Tools 286
12.1 Introduction 286
12.2 Materials and Methods 287
12.2.1 Data for This Investigation 287
12.2.2 Integral Turbulence Characteristics 287
12.2.3 Footprint Models 289
12.2.4 Energy Balance Closure 290
12.3 Results and Discussions 291
12.3.1 Integral Turbulence Characteristics 291
12.3.2 Footprints and Data Quality 297
12.3.2.1 Zero-Plane Displacement 297
12.3.2.2 Characteristics of the Underlying Surface 299
12.3.2.3 Footprint Climatology 300
12.3.2.4 Linking Footprint and Flux Data Quality 302
12.3.2.5 Coordinate Rotation 305
12.3.3 Energy Balance Closure 309
12.4 Conclusions 311
References 312
13 Interaction Forest–Clearing 318
13.1 Introduction 318
13.2 Materials and Methods 319
13.2.1 Special Installations at the Forest Edge 319
13.2.2 Methods Applied for This Investigation 321
13.2.2.1 Turbulence Data 321
13.2.2.2 Wavelet Analysis 322
13.3 Results and Discussions 323
13.3.1 Horizontal and Vertical Fields at the Forest Edge 323
13.3.2 Coupling Regime 326
13.3.3 Coherent Structures 328
13.3.4 Penetration of Large-Scale Coherent Structures 329
13.3.5 Energy Balance Closure Problem 332
13.4 Conclusions 334
References 336
14 Forest Climate in Vertical and Horizontal Scales 339
14.1 Introduction 339
14.2 Material and Methods 341
14.2.1 Vertical Profile Measurements 341
14.2.1.1 Long-Term Measurements 341
14.2.1.2 EGER Project 342
14.2.1.3 Vertical Coupling Regimes 342
14.2.2 Horizontal Profile Measurements 343
14.2.2.1 Advection Measurements 343
14.2.2.2 Horizontal Mobile Measuring System 344
14.3 Results and Discussions 345
14.3.1 Microclimate Within and Above a Dense Forest 345
14.3.1.1 Vertical (Turbulent) Exchange 346
14.3.1.2 Horizontal and Vertical Advection 351
14.3.2 Microclimate at a Forest Edge 352
14.4 Conclusions 357
References 358
15 Catchment Evapotranspiration and Runoff 362
15.1 Introduction 362
15.2 Materials and Methods 364
15.2.1 Hydrological Characterization of the Catchment 364
15.2.1.1 Data 365
15.2.1.2 Statistical Approaches 367
15.2.2 Principal Component Analysis of Time Series 367
15.3 Results and Discussion 368
15.3.1 Long-Term Budgets 368
15.3.1.1 Reliability of Long-Term Budget Data 368
15.3.1.2 Role of Vegetation 371
15.3.1.3 Relation to Residence Time and Size of the Groundwater Store 371
15.3.2 Short-Term Dynamics 372
15.3.2.1 Hydrological Signals Generated in the Topsoil 372
15.3.2.2 Hydrological Signals Propagating Through the Subsoil 376
15.3.3 Evapotranspiration in Hydrological and Hydrogeological Model Approaches 378
15.4 Conclusions 379
References 380
Part IV Modelling Studies of Energy and Matter Fluxes 383
16 Modeling of Energy and Matter Exchange 384
16.1 Introduction 384
16.2 Materials and Methods 386
16.2.1 Model Descriptions 386
16.2.1.1 FLAME 386
16.2.1.2 ACASA 387
16.2.1.3 STANDFLUX and SVAT-CN 388
16.2.2 Model Drivers and Input Parameters 389
16.2.2.1 FLAME 389
16.2.2.2 ACASA, STANDFLUX, and SVAT-CN 390
16.2.3 Reference Eddy-Covariance Measurements 395
16.3 Results and Discussions 396
16.3.1 ACASA-FLAME Intercomparison 396
16.3.2 ACASA: 3D STANDFLUX Intercomparison 400
16.3.3 ACASA Annual Calculations: The Year 2003 404
16.3.4 ACASA Tile Approach for Forest and Clearing 406
16.3.5 3D SVAT-CN Simulation 411
16.4 Discussion and Conclusions 413
References 416
17 Complexity of Flow Structures and Turbulent Transport in Heterogeneously Forested Landscapes: Large-Eddy Simulation Study of the Waldstein Site 420
17.1 Introduction 420
17.2 Material and Methods 422
17.2.1 Large-Eddy Simulation Model 422
17.2.2 EGER-Case Selection and Simulation Setup 423
17.2.3 Determination of Tree Heights and Leaf Area Distribution 425
17.2.4 Data Output and Analysis 428
17.3 Results and Discussions 428
17.3.1 Mean Flow Structures 428
17.3.2 Temperature and Tracer Distributions 432
17.3.3 Spatial Variability of Turbulent Transports 435
17.4 Conclusions 438
References 439
18 Comparison of Meso-Scale Modelled Fluxes and Measurements 442
18.1 Introduction 442
18.2 Material and Methods 443
18.2.1 Measuring Site and Climatic Characteristics 443
18.2.2 Configuration and Evaluation of the WRF-ARW Model 444
18.3 Results and Discussion 447
18.3.1 Predictive Quality of State Variables 447
18.3.1.1 Temperature 447
18.3.1.2 Global Radiation 450
18.3.1.3 Wind Speed 450
18.3.1.4 Wind Direction 453
18.3.2 Predictive Quality of Turbulent Energy Fluxes 454
18.3.3 Influence of Large-Scale Weather Patterns 458
18.4 Conclusions 459
References 461
Part V Conclusions 463
19 What Can We Learn for a Better Understanding of the Turbulent Exchange Processes Occurring at FLUXNET Sites? 464
19.1 Introduction 464
19.2 Flux Measurements in a Changing Environment 466
19.2.1 Climate Change 466
19.2.2 Instrumental Problems 467
19.2.3 Influence of the Heterogeneity 469
19.2.4 Influences of the Atmospheric Boundary Layer 470
19.3 Linking Atmospheric Turbulence and Air Chemistry 471
19.4 Further Remarkable Results 472
19.5 Relevant Results for the FLUXNET Network 473
19.5.1 Optimal Data Quality Control 473
19.5.2 Recommendations for FLUXNET Data Analysis 474
References 475
Appendices 479
Appendix AInstrumentation of the Permanent and Periodic Measuring Programs of the Waldstein Measuring Sites 480
Compiled by Thomas Foken, Johannes Lüers, Andreas Held, Christoph K. Thomas, and Andrei Serafimovich 480
References 512
Appendix BImportant Measurements at Waldstein-Pflanzgarten and Waldstein-Weidenbrunnen Sites 515
Compiled by Johannes Lüers, Wolfgang Babel, and Corinna Rebmann 515
Reference 523
Appendix CFLUXNET Overview Papers in Which Data Sets of the Waldstein-Weidenbrunnen Site Are Used 524
Compiled by Thomas Foken 524
References 524
Index 527