203
8
An Outline of
Lagrangian Stochastic
Dispersion Models
Domenico Anfossi and Silvia Trini Castelli
CONTENTS
8.1 Introduction ..................................................................................................203
8.2 Generalities on Lagrangian Stochastic Models ............................................205
8.3 Asymmetric PDFs .........................................................................................208
8.3.1 Bi-Gaussian PDF ..............................................................................208
8.3.2 Gram–Charlier PDF ......................................................................... 210
8.4 Solutions of the 1-D Langevin Equation ....................................................... 211
8.5 The Low Wind Case ..................................................................................... 212
8.6 Inverse Modeling .......................................................................................... 214
8.7 Complementary Information ........................................................................ 215
8.7.1 Turbulence and Flow Fields .............................................................. 215
8.7.2 Boundary Conditions ........................................................................ 216
8.7.3 Plume Rise ........................................................................................ 217
8.7.4 Concentration Calculation ................................................................ 220
8.7.5 Dense Gas Dispersion ....................................................................... 221
8.8 Example of LSDM Applications .................................................................. 222
8.8.1 SPRAY Model .................................................................................. 222
8.8.2 Validation versus Experiments ......................................................... 222
8.8.3 Single Sources and Linear Emissions: Impact Assessment in
Complex Terrain ...............................................................................224
8.8.4 Inverse Modeling Examples ............................................................. 228
8.9 Conclusions ................................................................................................... 230
References .............................................................................................................. 231
8.1 INTRODUCTION
The dispersion of airborne pollutant in the planetary boundary layer (PBL) is
governed, schematically, by the transport, operated by the mean wind, and by the
atmospheric turbulence due to the presence of eddies having different spatial and
temporal scales.
© 2010 by Taylor and Francis Group, LLC
8
An Outline of
Lagrangian Stochastic
Dispersion Models
Domenico Anfossi and Silvia Trini Castelli
CONTENTS
8.1 Introduction ..................................................................................................203
8.2 Generalities on Lagrangian Stochastic Models ............................................205
8.3 Asymmetric PDFs .........................................................................................208
8.3.1 Bi-Gaussian PDF ..............................................................................208
8.3.2 Gram–Charlier PDF ......................................................................... 210
8.4 Solutions of the 1-D Langevin Equation ....................................................... 211
8.5 The Low Wind Case ..................................................................................... 212
8.6 Inverse Modeling .......................................................................................... 214
8.7 Complementary Information ........................................................................ 215
8.7.1 Turbulence and Flow Fields .............................................................. 215
8.7.2 Boundary Conditions ........................................................................ 216
8.7.3 Plume Rise ........................................................................................ 217
8.7.4 Concentration Calculation ................................................................ 220
8.7.5 Dense Gas Dispersion ....................................................................... 221
8.8 Example of LSDM Applications .................................................................. 222
8.8.1 SPRAY Model .................................................................................. 222
8.8.2 Validation versus Experiments ......................................................... 222
8.8.3 Single Sources and Linear Emissions: Impact Assessment in
Complex Terrain ...............................................................................224
8.8.4 Inverse Modeling Examples ............................................................. 228
8.9 Conclusions ................................................................................................... 230
References .............................................................................................................. 231
8.1 INTRODUCTION
The dispersion of airborne pollutant in the planetary boundary layer (PBL) is
governed, schematically, by the transport, operated by the mean wind, and by the
atmospheric turbulence due to the presence of eddies having different spatial and
temporal scales.
© 2010 by Taylor and Francis Group, LLC