Hydrometeorology

Christopher G. Collier received a BSc in Physics and ARCS in Science at Imperial College, London in 1968. Subsequently he received a PhD (1999) and a DSc (2008) from the University of Salford. He joined the Meteorological Office in 1968, and later chaired the European Union International Weather Radar Networking project, and served on numerous World Meteorological Organisation (WMO), BNSC, EUMETSAT, ESA and NERC committees. He is a Chartered Meteorologist of the Royal Meteorological Society, and was President of that Society 2004-2006 being elected an Honorary Fellow in 2012, and served on the committees of the British Hydrological Society. He is a member of the American Meteorological Society. He left the Met Office in 1995 becoming a Professor of Environmental Remote Sensing at the University of Salford, and joined the National Centre for Atmospheric Science based at the University of Leeds becoming Professor of Atmospheric Science and Head of Strategic Partnerships in 2009. He was awarded the First Vaisala Prize for radar measurements of precipitation in 1986.

• Series Foreword xivPreface xv  Acknowledgements xviiAbout the Companion Website xviii1 The Hydrological Cycle 11.1 Overview 11.2 Processes comprising the hydrological cycle 31.3 Global influences on the hydrological cycle 41.4 Water balance 61.5 Impact of aerosols on the hydrological cycle 61.6 Coupled models for the hydrological cycle 71.7 Global Energy and Water Cycle Exchanges Project (GEWEX) 81.8 Flooding 8Summary of key points in this chapter 9Problems 10References 102 Precipitation 112.1 Introduction 112.2 Equation of state for a perfect gas 112.3 Hydrostatic pressure law 122.4 First law of thermodynamics 122.5 Atmospheric processes: dry adiabatic lapse rate 132.6 Water vapour in the atmosphere 152.7 Atmospheric processes: saturated adiabatic lapse rate 162.8 Stability and convection in the atmosphere 162.9 The growth of precipitation particles 182.10 Precipitation systems 212.10.1 Localized convection 222.10.2 Mesoscale precipitation systems 232.10.3 Mid‐latitude depressions 262.10.4 Tropical storms 302.10.5 Orographic effects on precipitation distribution 312.10.6 Topographical effects on precipitation distribution 332.11 Global atmospheric circulation 33Appendix 2.1 Growth of a raindrop 33Summary of key points in this chapter 35Problems 36References 373 Evaporation and Transpiration 413.1 Introduction 413.2 Modelling potential evaporation based upon observations 413.3 Aerodynamic approach 423.4 Energy balance 443.5 The Penman equation 443.6 Sensible and water vapour fluxes 453.7 Evaporation of water from wet vegetation surfaces: the interception process 473.8 Measuring evaporation and transpiration 473.9 Water circulation in the soil–plant–atmosphere continuum 483.10 Water circulation and transpiration 503.11 Water flux in plants 503.12 Modelling land surface temperatures and fluxes 513.13 Soil–vegetation–atmosphere transfer schemes 543.14 Estimation of large scale evapotranspiration and total water storage in a river basin 56Appendix 3.1 Combination of aerodynamic and energy balance methods of computing lake evaporation 57Appendix 3.2 Modelling soil moisture wetness 57Summary of key points in this chapter 58Problems 59References 604 Snow and Ice 634.1 Introduction 634.2 Basic processes 634.2.1 Formation of snow 634.2.2 Formation of snow cover and its effects on the atmosphere 654.2.3 Formation of ice 674.3 Characteristics of snow cover 684.4 Glaciers 704.5 Sea ice 714.6 Permafrost 714.7 The physics of melting and water movement through snow 714.8 Water equivalent of snow 744.9 Modelling snowmelt and stream flow 764.10 Snow avalanches 804.11 Worldwide distribution and extremes of snow cover 81Appendix 4.1 Estimates of catchment snowmelt inflow rates 83Summary of key points in this chapter 84Problems 86References 875 Measurements and Instrumentation 905.1 Measurement, resolution, precision and accuracy 905.2 Point measurements of precipitation 905.2.1 Raingauge types 905.2.2 Measuring snow and hail 925.2.3 Errors in measurement 945.3 Areal measurements of precipitation using raingauge networks 965.4 Radar measurements of rainfall 965.4.1 Basics 965.4.2 Errors in radar measurements 975.4.3 Adjustment using raingauges 1015.4.4 Summary of problem areas associated with radar measurements of precipitation 1025.4.5 The use of multi‐parameter radar 1035.4.6 Drop size distributions 1045.4.7 Rainfall estimation using parametric variables 1045.4.8 Measurement of snow 1065.4.9 Measurement of hail 1075.4.10 Precipitation type 1085.5 Soil moisture 1095.5.1 Approaches 1095.5.2 Gravimetric method 1095.5.3 Electrical resistance method 1105.5.4 Neutron method 1105.5.5 Gamma ray attenuation method 1105.5.6 COSMOS‐UK 1115.5.7 Dielectric methods 1115.5.8 Tensiometric method 1135.5.9 Satellite remote sensing 1135.6 Evaporation and evapotranspiration 1135.7 Flow measurement: basic hydrometry 1135.8 Measuring stream discharge 1155.8.1 The stage‐discharge curve 1155.8.2 Automated moving boat methods 1175.9 Brief overview of modern telemetry 1175.9.1 Ground‐based telemetry links 1175.9.2 VHF and UHF radio links 1175.9.3 Satellite links 118Appendix 5.1 Combining dissimilar estimates by the method of least squares 118Summary of key points in this chapter 119Problems 121References 1216 Satellite‐Based Remote Sensing 1256.1 Overview of satellite remote sensing 1256.2 Surface scattering of electromagnetic radiation 1296.3 Interaction of electromagnetic radiation with the atmosphere 1316.4 Visible and infrared data 1326.4.1 Precipitation 1346.4.2 Snow depth 1356.4.3 Soil moisture and evapotranspiration 1366.5 Multispectral data 1376.5.1 Precipitation 1376.5.2 Cloud recognition 1376.5.3 Snow 1386.6 Passive microwave techniques 1386.6.1 Precipitation 1416.6.2 Global Precipitation Climatology Project (GPCP) 1436.6.3 Global Precipitation Measurement mission (GPM) 1436.6.4 Snow depth 1436.6.5 Sea ice and sea surface temperature 1456.6.6 Soil moisture and evapotranspiration 1456.7 Active (radar) microwave techniques 1476.7.1 Synthetic aperture radar 1476.7.2 Radar systems 1496.7.3 Tropical Rainfall Measuring Mission (TRMM) 1506.8 The surface energy balance system (SEBS) 1506.9 Summary of satellite measurement issues 151Appendix 6.1 Radiation balance 154Summary of key points in this chapter 155Problems 157References 1577 Analysis of Precipitation Fields and Flood Frequency 1637.1 Introduction 1637.2 Areal mean precipitation 1637.3 Spatial and temporal storm analysis 1657.3.1 Spatial statistical analyses 1657.3.2 Temporal analyses 1677.3.3 Oscillations in precipitation 1687.3.4 Conditional probabilities 1697.3.5 Kriging 1697.3.6 Accuracy of the precipitation products 1717.4 Model storms for design 1727.5 Approaches to estimating flood frequency 1737.6 Probable maximum precipitation (PMP) 1757.7 Probable maximum flood (PMF) 1777.8 Flood Studies Report (FSR) 1777.9 Flood Estimation Handbook (FEH) 180Appendix 7.1 Three-dimensional description of a rainfall surface 182Appendix 7.2 Gumbel distribution 183Summary of key points in this chapter 183Problems 185References 1858 Precipitation Forecasting 1888.1 Introduction 1888.2 Nowcasting 1888.2.1 Definition 1888.2.2 Impact of errors in precipitation measurements 1898.2.3 Extrapolation of radar data 1898.3 Probabilistic radar nowcasting 1928.4 Numerical models: structure, data requirements, data assimilation 1948.4.1 Probabilistic quantitative precipitation forecasting 1948.4.2 Mesoscale models 1978.4.3 Data assimilation 1978.4.4 Performance of high resolution mesoscale model‐based nowcasting systems 1988.5 Medium range forecasting 1988.6 Seasonal forecasting 201Appendix 8.1 Brier skill score 203Summary of key points in this chapter 203Problems 205References 2059 Flow Forecasting 2099.1 Basic flood forecasting techniques 2099.2 Model calibration and equifinality 2109.3 Flood forecasting model development 2109.4 Conversion of detailed hydrodynamic models to simplified models suitable for real‐time flood forecasting 2139.5 Probabilistic flood forecasting and decision support methods 2159.6 Derivation of station rating (stage‐discharge) curves 2169.7 Performance testing of forecasting models and updating procedures 2169.8 Configuration of models on to national and international forecasting platforms 2189.9 Flood warnings and levels of service 2229.9.1 United Kingdom 2229.9.2 United States and Canada 2229.10 Case studies worldwide: river and urban 224Appendix 9.1 St Venant equations 224Appendix 9.2 Flow in unsaturated and saturated zones 226Summary of key points in this chapter 227Problems 228References 22910 Coastal Flood Forecasting 23310.1 Types of coastal flooding 23310.2 Models used to predict storm surge flooding 23310.2.1 Empirical models 23410.2.2 First‐generation models 23510.2.3 Second‐generation models 23510.2.4 Third‐generation models 23510.2.5 Wave, tide and surge models 23510.3 Probabilistic surge forecasting 23810.4 Tsunamis 23910.5 Examples of coastal flooding in the United Kingdom 24110.5.1 The surge of 1953 24110.5.2 Wirral floods 2013 24110.5.3 Surges along the east coast of England, December 2013 24110.5.4 Aberystwyth floods January 2014 24210.6 Some examples of coastal flooding worldwide 243Appendix 10.1 Wave overtopping at the coast 244Summary of key points in this chapter 245Problems 247References 24711 Drought 24911.1 Definitions 24911.2 Drought indices 25011.3 The physics of drought 25311.4 Frequency analysis: predictability 25411.5 Modelling the occurrence of drought 25611.6 Major drought worldwide 25811.7 Examples of the consequences of drought 25811.8 Strategies for drought protection, mitigation or relief 260Appendix 11.1 Defining aridity 261Summary of key points in this chapter 261Problems 263References 26312 Wind and the Global Circulation 26612.1 Equations of motion 26612.2 Atmospheric Ekman layer 26812.3 Fronts 26912.4 Jet streams 27012.5 Hurricanes 27112.6 Lee waves 27212.7 Land and sea breezes 27212.8 The wind structure of the atmospheric circulation 27312.9 Hadley cell 27312.10 Polar cell 27412.11 Ferrel cell 27512.12 Walker circulation 27512.13 El Niño/Southern Oscillation 27612.14 Monsoons 276Appendix 12.1 Large scale air motion 278Appendix 12.2 Ageostrophic motion 278Summary of key points in this chapter 279Problems 281References 28213 Climatic Variations and the Hydrological Cycle 28413.1 An introduction to climate 28413.2 Evidence of climate change 28613.2.1 Climatology of the last ice age 29213.2.2 Intergovernmental Panel on Climate Change (IPCC) 29513.3 Causes of climatic change 29713.3.1 The natural energy system 29813.3.2 The hydrological cycle 29913.3.3 The carbon cycle 30113.3.4 Other biochemical cycles 30113.4 Modelling climatic change 30313.5 Possible effects of climate change upon the hydrological cycle and water resources 307Appendix 13.1 Estimating return times for events in a long term climate record 310Summary of key points in this chapter 310Problems 313References 31414 Hydrometeorology in the Urban Environment 31814.1 Introduction 31814.2 Urban boundary layer and the water cycle 31814.3 Urban development and rainfall 32014.4 Sewer flooding 32214.5 Surface runoff from urban areas 32414.6 Floodplain development 32614.7 Acid rain 32714.7.1 Basics 32714.7.2 Modelling wet deposition 32814.8 Urban air and water pollution 329Appendix 14.1 Number of runoff events from an urban drainage system 330Summary of key points in this chapter 331Problems 332References 333Glossary 336Index 347