Table of Contents
Acknowledgements v
Summary x
List of Tables xix
List of Figures xx
Chapter 1. Introduction 1
1.1 Motivation . . . 1
1.2 Scope of chapters . . . 3
1.3 Ice sheets and glaciers . . . 4
1.3.1 Surface mass balance . . . 5
1.4 Ice as a climate archive . . . 6
1.4.1 The Mid-Pleistocene Transition . . . 6
1.4.2 The Beyond Epica Oldest Ice project in a nutshell . . . 8
1.5 Characteristics of polythermal glaciers and ice sheets . . . 10
1.5.1 Polythermal structure . . . 11
Chapter 2. The thermodynamics and thermomechanics of ice 15 2.1 Thermal regimes . . . 16
2.1.1 Thermal conduction and Fourier’s law . . . 16
2.1.2 Vertical advection . . . 19
2.1.3 Dirichlet and Neumann boundary conditions . . . 21
2.1.3.1 Surface temperature . . . 23
2.1.3.2 Geothermal heat flux . . . 24
2.1.4 Derived temperature profile . . . 29
2.1.5 Three dimensional advection . . . 30
2.2 The pressure melting point . . . 31
2.3 Mechanical regimes . . . 32
2.3.1 Stress . . . 32
2.3.2 Strain . . . 33
2.3.3 Frictional heating . . . 33
2.4 Additional sources of heat: latent heat . . . 35
2.5 Mechanical models . . . 37
2.6 Thermomechanical ice-flow models . . . 39
Chapter 3. The climate memory of an Arctic polythermal glacier 42 3.1 Introduction . . . 42
3.2 Field data and radar analysis . . . 43
3.3 Modelling englacial temperature change . . . 48
3.4 Validity of the diffusion model . . . 51
3.5 Reconstructing ELA trends . . . 56
3.6 Discussion . . . 59
3.7 Conclusions . . . 60
3.8 Appendix: Model description . . . 62
Chapter 4. Constraints on thermodynamical modelling of the Antarctic Ice sheet 65 4.1 The Antarctic Ice Sheet in a nutshell . . . 66
4.1.1 Deep ice core sites . . . 67
4.2 Antarctic Ice Sheet geometry . . . 70
4.3 Surface ice velocity and ice flow . . . 73
4.4 Mass balance . . . 75
4.4.1 Surface air temperature . . . 75
4.4.2 Surface mass balance . . . 76
4.5 Geothermal heat flux . . . 78
4.5.1 Overview . . . 78
4.5.2 Current data sets . . . 80
4.5.3 Greenland data . . . 85
4.6 Subglacial lakes . . . 86
4.7 Antarctic Ice Sheet reconstructions of the last 1.5 Ma . . . 89
Chapter 5. Using ice-flow models to evaluate potential sites of million year-old ice in Antarctica 93 5.1 Introduction . . . 95
5.2 Why obvious drill sites are unsuitable . . . 97
5.3 Uncertainties in Antarctic GHF and the location of oldest ice . . . 100
5.3.1 Data sets and model setup . . . 100
5.3.2 Results . . . 102
5.4 Thermomechanical ice-flow modelling . . . 104
5.4.1 Model description . . . 105
5.4.2 Velocity field . . . 106
5.4.3 Input data calibration . . . 108
5.4.4 Subglacial lake correction . . . 109
5.5 Ensemble model results . . . 110
5.6 Discussion and conclusions . . . 112
Chapter 6. Promising Oldest Ice sites in East Antarctica based on thermody-namical modelling 117 6.1 Introduction . . . 119
6.2 Thermodynamical modelling . . . 124
6.2.1 Steady-state model . . . 124
6.2.2 Transient model description . . . 125
6.2.3 Model forcing . . . 126
6.2.4 Limit values of GHF . . . 127
6.2.4.1 Constraints on GHF . . . 128
6.2.5 Constraints on Oldest Ice candidate sites . . . 129
6.3 Results . . . 131
6.3.1 Large-scale GHF probability distributions . . . 131
6.3.2 Small-scale GHF probabilities and Oldest Ice: Dome Fuji and Dome C . . . 133
6.4 Discussion . . . 138
6.4.1 Surface temperature forcing . . . 138
6.4.2 Limits on Gpmpcalculation . . . 139
6.4.3 Steady-state model comparison . . . 140
6.5 Conclusion and implications for Oldest Ice candidate sites . . . 143
6.5.1 Dome Fuji . . . 143
6.5.2 Dome C . . . 144
Chapter 7. Discussion 145
7.1 Oldest Ice site developments . . . 145
7.1.1 Dome C . . . 145
7.1.2 Dome Fuji . . . 150
7.1.3 Dome A . . . 152
7.1.4 South Pole . . . 154
7.1.5 Blue ice and debris glaciers . . . 155
7.2 Oldest Ice constraints . . . 156
Chapter 8. Conclusion and perspectives 157 8.1 General findings . . . 157
8.2 Future work . . . 159
References 162
