Snow and Climate Physical Processes Surface Energy Exchange and Modeling

Richard L. Armstrong, Eric Brun0521854547

The extent and variability of seasonal snow cover are important parameters in the climate system, due to their effects on energy and moisture budgets, and because surface temperature is highly dependent on snow cover. In turn, snow cover trends serve as key indicators of climate change. Many distinct techniques have become available to study snow-climate relationships. Satellites provided the first capability for monitoring snow cover extent at continental and hemispheric scales, and there have been rapid advances in snow modeling physics to represent snow cover and snow processes in Global Climate Models (GCMs). These advances have changed the way we look at snow cover. The main goal of this book is to provide a synthesis of the prevailing state of snow-climate science that reflects this distinct perspective. This volume provides an excellent synthesis for researchers and advanced students.

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Table of contents :
Cover……Page 1
Half-title……Page 3
Title……Page 5
Copyright……Page 6
Dedication……Page 7
Contents……Page 9
List of contributors……Page 11
Preface……Page 13
References……Page 14
Acknowledgments……Page 15
Nomenclature……Page 16
Subscripts……Page 24
1.1 Basic properties of snow……Page 25
1.2 Importance of snow in the climate system……Page 28
1.3 Importance of snow in natural and human systems……Page 30
1.4 Climate change implications……Page 31
References……Page 33
2.1 Introduction……Page 36
2.1.1 Cloud formation and precipitation……Page 37
2.1.2 Snow formation and crystal type……Page 38
2.2 General characteristics……Page 43
Constitution……Page 44
Snow classification……Page 45
Bulk equilibrium temperature in a pure water system……Page 47
The effect of curvature on phase equilibrium in snow……Page 48
Dry snow metamorphism……Page 51
2.2.4 Grain size and growth rate……Page 53
Measurement of snow density and liquid water content……Page 55
Compaction rate……Page 56
2.3.1 Thermal properties……Page 59
Specific heat……Page 60
2.3.2 Advective–diffusive heat transfer……Page 62
2.4 Fluid flow behavior in snow……Page 64
2.4.1 Saturated or one-phase flow……Page 65
Saturated or air permeability……Page 66
Forced and natural convection of air……Page 68
2.4.2 Unsaturated or two-phase flow……Page 70
Capillary forces and the pressure–saturation………Page 71
Flow with a uniform wetting front……Page 73
Unstable flow……Page 74
2.5.1 Reflectance and bi-directional reflectance……Page 77
2.5.2 Snow albedo……Page 78
Effects of snow type on the albedo……Page 79
Large-scale effects on snow albedo……Page 81
2.6 Summary and future directions……Page 82
References……Page 86
3.1 Introduction……Page 94
3.2 Equations of energy and mass balance……Page 95
3.3 The fluxes involved in the energy balance……Page 97
3.3.1 Shortwave radiation……Page 98
3.3.2 Longwave radiation……Page 99
3.3.4 Turbulent heat fluxes……Page 100
3.3.5 Heat fluxes over a non-uniform snow cover……Page 106
3.4.1 Interception by vegetation……Page 107
3.4.2 Blowing snow……Page 110
3.4.3 Accumulation in alpine topography……Page 115
3.5 Examples of energy and mass balances……Page 116
Energy balance……Page 118
Modeling aspects……Page 119
Energy balance……Page 122
Energy balance……Page 125
Modeling aspects……Page 127
Relevance and characteristics……Page 128
Energy balance……Page 137
Modeling aspects……Page 140
Relevance and characteristics……Page 141
Site……Page 143
Energy balance……Page 144
Modeling aspects……Page 147
References……Page 148
4.1.2 Snow-cover simulation models……Page 157
4.2.1 Introduction……Page 161
4.2.2 Description of recent snow models……Page 162
4.3.1 Introduction……Page 168
4.3.2 Sensitivity to albedo parameterization……Page 169
4.3.3 Sensitivity to the parameterization of water retention……Page 171
4.3.4 Sensitivity to the parameterization of turbulent fluxes……Page 173
4.3.5 Sensitivity to the snow–rain criterion……Page 175
4.3.6 Conclusions……Page 176
4.4.1 Introduction……Page 177
4.4.2 Thermal and hydraulic properties of snow……Page 180
4.4.3 Snow albedo……Page 183
4.4.4 Snow energy and mass balances……Page 185
4.4.5 Heterogeneous snow cover……Page 186
4.4.6 Snow and vegetation……Page 187
4.5 The global snow coverage in climate change scenarios……Page 188
4.5.1 Snow-cover variability……Page 189
4.5.2 Snow–climate feedback……Page 193
4.5.3 Climate change scenarios……Page 195
4.5.4 Conclusions……Page 202
References……Page 203
5.1 Introduction……Page 213
5.2.1 Pre-instrumental data……Page 214
5.2.2 Snow depth……Page 215
5.2.3 Snow water equivalent……Page 219
5.2.5 Snowfall and solid precipitation……Page 222
5.3.1 Visible-band satellite data……Page 224
5.3.2 High-resolution/multi-spectral data……Page 226
5.3.3 Other regional-scale snow products based on visible data……Page 227
5.3.4 Passive microwave satellite data……Page 228
5.3.5 Active microwave systems……Page 233
5.3.6 New sensor systems……Page 234
5.4.1 Snow depth……Page 235
5.4.2 Snow extent……Page 236
5.5 Global–continental snow-cover climatology: measured and modeled……Page 237
References……Page 239
Appendix: Snow model questionnaire……Page 249
Index……Page 252