Terrestrial Hydrometeorology

Dr. Shuttleworth worked for 20 years at the UK s Institute of Hydrology, ultimately as Head of the Hydrological Processes Division. In 1993 he joined the University of Arizona where he is Regents' Professor in both the Department of Hydrology and Water Resources and the Atmospheric Sciences Department. He has served on numerous national and international scientific advisory committees, including the National Research Council, the International Council of Scientific Unions, the International Hydrology Programme, the International Geosphere-Biosphere Programme, and the World Climate Research Programme. In 2001 Dr. Shuttleworth was awarded the AGU Hydrology Prize for "outstanding contributions to the science of hydrology", and in 2006 IAHS, UNESCO and WMO jointly awarded him the prestigious International Hydrology Prize.

Foreword xvi Preface xviii Acknowledgements xix 1 Terrestrial Hydrometeorology and the Global Water Cycle 1 Introduction 1 Water in the Earth system 2 Components of the global hydroclimate system 4 Atmosphere 5 Hydrosphere 8 Cryosphere 9 Lithosphere 9 Biosphere 10 Anthroposphere 10 Important points in this chapter 12 2 Water Vapor in the Atmosphere 14 Introduction 14 Latent heat 14 Atmospheric water vapor content 15 Ideal Gas Law 16 Virtual temperature 17 Saturated vapor pressure 18 Measures of saturation 20 Measuring the vapor pressure of air 21 Important points in this chapter 23 3 Vertical Gradients in the Atmosphere 25 Introduction 25 Hydrostatic pressure law 26 Adiabatic lapse rates 27 Dry adiabatic lapse rate 27 Moist adiabatic lapse rate 28 Environmental lapse rate 28 Vertical pressure and temperature gradients 29 Potential temperature 30 Virtual potential temperature 31 Atmospheric stability 32 Static stability parameter 32 Important points in this chapter 34 4 Surface Energy Fluxes 36 Introduction 36 Latent and sensible heat fluxes 37 Energy balance of an ideal surface 38 Net radiation, Rn 38 Latent heat flux, lE 39 Sensible heat flux, H 39 Soil heat flux, G 39 Physical energy storage, St 40 Biochemical energy storage, P 40 Advected energy, Ad 41 Flux sign convention 41 Evaporative fraction and Bowen ratio 45 Energy budget of open water 46 Important points in this chapter 46 5 Terrestrial Radiation 48 Introduction 48 Blackbody radiation laws 49 Radiation exchange for gray surfaces 51 Integrated radiation parameters for natural surfaces 52 Maximum solar radiation at the top of atmosphere 54 Maximum solar radiation at the ground 56 Atmospheric attenuation of solar radiation 58 Actual solar radiation at the ground 59 Longwave radiation 59 Net radiation at the surface 62 Height dependence of net radiation 63 Important points in this chapter 64 6 Soil Temperature and Heat Flux 66 Introduction 66 Soil surface temperature 66 Subsurface soil temperatures 67 Thermal properties of soil 68 Density of soil, rs 69 Specific heat of soil, cs 70 Heat capacity per unit volume, Cs 70 Thermal conductivity, ks 70 Thermal diffusivity, as 71 Formal description of soil heat flow 71 Thermal waves in homogeneous soil 72 Important points in this chapter 75 7 Measuring Surface Heat Fluxes 77 Introduction 77 Measuring solar radiation 77 Daily estimates of cloud cover 77 Thermoelectric pyranometers 78 Photoelectric pyranometers 79 Measuring net radiation 80 Measuring soil heat flux 81 Measuring latent and sensible heat 82 Micrometeorological measurement of surface energy fluxes 83 Bowen ratio/energy budget method 83 Eddy correlation method 85 Evaporation measurement from integrated water loss 87 Evaporation pans 88 Watersheds and lakes 89 Lysimeters 90 Soil moisture depletion 91 Comparison of evaporation measuring methods 91 Important points in this chapter 94 8 General Circulation Models 96 Introduction 96 What are General Circulation Models? 96 How are General Circulation Models used? 98 How do General Circulation Models work? 100 Sequence of operations 100 Solving the dynamics 102 Calculating the physics 103 Intergovernmental Panel on Climate Change (IPCC) 104 Important points in this chapter 105 9 Global Scale Influences on Hydrometeorology 107 Introduction 107 Global scale influences on atmospheric circulation 107 Planetary interrelationship 109 Latitudinal differences in solar energy input 109 Seasonal perturbations 109 Daily perturbations 109 Persistent perturbations 109 Contrast in ocean to continent surface exchanges 109 Continental topography 109 Temporary perturbations 110 Perturbations in oceanic circulation 110 Perturbations in atmospheric content 110 Perturbations in continental land cover 110 Latitudinal imbalance in radiant energy 110 Lower atmosphere circulation 111 Latitudinal bands of pressure and wind 111 Hadley circulation 112 Mean low-level circulation 113 Mean upper level circulation 115 Ocean circulation 116 Oceanic influences on continental hydroclimate 118 Monsoon flow 118 Tropical cyclones 119 El Nino Southern Oscillation 120 Pacific Decadal Oscillation 122 North Atlantic Oscillation 123 Water vapor in the atmosphere 123 Important points in this chapter 126 10 Formation of Clouds 128 Introduction 128 Cloud generating mechanisms 129 Cloud condensation nuclei 131 Saturated vapor pressure of curved surfaces 132 Cloud droplet size, concentration and terminal velocity 133 Ice in clouds 134 Cloud formation processes 135 Thermal convection 135 Foehn effect 136 Extratropical fronts and cyclones 138 Cloud genera 140 Important points in this chapter 141 11 Formation of Precipitation 143 Introduction 143 Precipitation formation in warm clouds 144 Precipitation formation in other clouds 146 Which clouds produce rain? 148 Precipitation form 149 Raindrop size distribution 150 Rainfall rates and kinetic energy 151 Forms of frozen precipitation 151 Other forms of precipitation 152 Important points in this chapter 153 12 Precipitation Measurement and Observation 155 Introduction 155 Precipitation measurement using gauges 156 Instrumental errors 157 Site and location errors 157 Gauge designs 160 Areal representativeness of gauge measurements 162 Snowfall measurement 165 Precipitation measurement using ground-based radar 168 Precipitation measurement using satellite systems 171 Cloud mapping and characterization 171 Passive measurement of cloud properties 172 Spaceborne radar 173 Important points in this chapter 174 13 Precipitation Analysis in Time 176 Introduction 176 Precipitation climatology 177 Annual variations 177 Intra-annual variations 177 Daily variations 180 Trends in precipitation 181 Running means 182 Cumulative deviations 183 Mass curve 184 Oscillations in precipitation 186 System signatures 187 Intensity-duration relationships 189 Statistics of extremes 190 Conditional probabilities 195 Important points in this chapter 196 14 Precipitation Analysis in Space 198 Introduction 198 Mapping precipitation 199 Areal mean precipitation 200 Isohyetal method 200 Triangle method 202 Theissen method 202 Spatial organization of precipitation 203 Design storms and areal reduction factors 205 Probable maximum precipitation 207 Spatial correlation of precipitation 209 Important points in this chapter 211 15 Mathematical and Conceptual Tools of Turbulence 213 Introduction 213 Signature and spectrum of atmospheric turbulence 213 Mean and fluctuating components 216 Rules of averaging for decomposed variables 217 Variance and standard deviation 219 Measures of the strength of turbulence 220 Mean and turbulent kinetic energy 220 Linear correlation coefficient 221 Kinematic flux 223 Advective and turbulent fluxes 225 Important points in this chapter 229 16 Equations of Atmospheric Flow in the ABL 231 Introduction 231 Time rate of change in a fluid 232 Conservation of momentum in the atmosphere 234 Pressure forces 235 Viscous flow in fluids 236 Axis-specific forces 239 Combined momentum forces 242 Conservation of mass of air 243 Conservation of atmospheric moisture 244 Conservation of energy 245 Conservation of a scalar quantity 246 Summary of equations of atmospheric flow 247 Important points in this chapter 247 17 Equations of Turbulent Flow in the ABL 248 Introduction 248 Fluctuations in the ideal gas law 248 The Boussinesq approximation 249 Neglecting subsidence 250 Geostrophic wind 251 Divergence equation for turbulent fluctuations 252 Conservation of momentum in the turbulent ABL 252 Conservation of moisture, heat, and scalars in the turbulent ABL 254 Neglecting molecular diffusion 255 Important points in this chapter 258 18 Observed ABL Profiles: Higher Order Moments 259 Introduction 259 Nature and evolution of the ABL 259 Daytime ABL profiles 261 Nighttime ABL profiles 263 Higher order moments 265 Prognostic equations for turbulent departures 265 Prognostic equations for turbulent kinetic energy 269 Prognostic equations for variance of moisture and heat 271 Important points in this chapter 276 19 Turbulent Closure, K Theory, and Mixing Length 277 Introduction 277 Richardson number 277 Turbulent closure 279 Low order closure schemes 280 Local, first order closure 281 Mixing length theory 283 Important points in this chapter 288 20 Surface Layer Scaling and Aerodynamic Resistance 289 Introduction 289 Dimensionless gradients 290 Obukhov length 292 Flux-gradient relationships 293 Returning fluxes to natural units 294 Resistance analogues and aerodynamic resistance 296 Important points in this chapter 299 21 Canopy Processes and Canopy Resistances 300 Introduction 300 Boundary layer exchange processes 301 Shelter factors 306 Stomatal resistance 308 Energy budget of a dry leaf 310 Energy budget of a dry canopy 311 Important points in this chapter 314 22 Whole Canopy Interactions 316 Introduction 316 Whole-canopy aerodynamics and canopy structure 317 Excess resistance 319 Roughness sublayer 321 Wet canopies 323 Equilibrium evaporation 325 Evaporation into an unsaturated atmosphere 327 Important points in this chapter 332 23 Daily Estimates of Evaporation 334 Introduction 334 Daily average values of weather variables 335 Temperature, humidity, and wind speed 335 Net radiation 337 Open water evaporation 339 Reference crop evapotranspiration 341 Penman-Monteith equation estimation of ERC 342 Radiation-based estimation of ERC 344 Temperature-based estimation of ERC 345 Evaporation pan-based estimation of ERC 346 Evaporation from unstressed vegetation: the Matt-Shuttleworth approach 348 Evaporation from water stressed vegetation 353 Important points in this chapter 355 24 Soil Vegetation Atmosphere Transfer Schemes 359 Introduction 359 Basis and origin of land-surface sub-models 359 Developing realism in SVATS 362 Plot-scale, one-dimensional micrometeorological models 364 Improving representation of hydrological processes 367 Improving representation of carbon dioxide exchange 368 Ongoing developments in land surface sub-models 370 Important points in this chapter 373 25 Sensitivity to Land Surface Exchanges 380 Introduction 380 Influence of land surfaces on weather and climate 381 A. The influence of existing land-atmosphere interactions 383 1. Effect of topography on convection and precipitation 383 2. Contribution by land surfaces to atmospheric water availability 385 B. The influence of transient changes in land surfaces 385 1. Effect of transient changes in soil moisture 385 2. Effect of transient changes in vegetation cover 388 3. Effect of transient changes in frozen precipitation cover 389 4. Combined effect of transient changes 391 C. The influence of imposed persistent changes in land cover 392 1. Effect of imposed land cover change on near surface observations 392 2. Effect of imposed land-cover change on regional-scale climate 393 3. Effect of imposed heterogeneity in land cover 395 Important points in this chapter 398 26 Example Questions and Answers 404 Introduction 404 Example questions 404 Example Answers 418 Index 441