69
4
Parameterization of
Convective Boundary
Layer Turbulence
and Clouds in
Atmospheric Models
Pedro M. M. Soares, João Teixeira,
and Pedro M. A. Miranda
CONTENTS
4.1 Introduction .................................................................................................... 70
4.2 The Atmospheric Boundary Layer ................................................................. 71
4.2.1 Structure of the Convective BL .......................................................... 74
4.3 Parameterization of Turbulence in Atmospheric Models ............................... 75
4.3.1 The Turbulence Closure Problem ....................................................... 76
4.3.2 Turbulence Parameterization and First-Order Closures ..................... 77
4.3.3 Turbulent Kinetic Energy and Higher-Order Closures .......................80
4.3.4 Nonlocal Approaches.......................................................................... 82
4.3.4.1 Counter-Gradient ................................................................. 82
4.3.4.2 Mass-Flux ............................................................................ 83
4.3.5 Transfer of Properties at Interfaces .................................................... 89
4.3.5.1 Lateral Mixing ..................................................................... 89
4.3.5.2 Cloud-Top Entrainment ........................................................90
4.3.5.3 BL Top-Entrainment ............................................................90
4.4 Eddy Diffusivity/Mass-Flux Parameterization in the CBL ............................ 91
4.4.1 The Eddy Diffusivity/Mass-Flux Scheme .......................................... 91
4.4.2 Mass-Flux Contribution ......................................................................94
4.4.2.1 Updraft Model......................................................................94
4.4.2.2 The Mass-Flux Profi le .........................................................96
4.4.3 The K-Diffusion Contribution ............................................................ 98
4.4.4 EDMF-EMP Results ........................................................................... 98
4.4.4.1 Top-Entrainment ................................................................ 100
4.4.4.2 Comparison with Other Approaches ................................. 104
© 2010 by Taylor and Francis Group, LLC
4
Parameterization of
Convective Boundary
Layer Turbulence
and Clouds in
Atmospheric Models
Pedro M. M. Soares, João Teixeira,
and Pedro M. A. Miranda
CONTENTS
4.1 Introduction .................................................................................................... 70
4.2 The Atmospheric Boundary Layer ................................................................. 71
4.2.1 Structure of the Convective BL .......................................................... 74
4.3 Parameterization of Turbulence in Atmospheric Models ............................... 75
4.3.1 The Turbulence Closure Problem ....................................................... 76
4.3.2 Turbulence Parameterization and First-Order Closures ..................... 77
4.3.3 Turbulent Kinetic Energy and Higher-Order Closures .......................80
4.3.4 Nonlocal Approaches.......................................................................... 82
4.3.4.1 Counter-Gradient ................................................................. 82
4.3.4.2 Mass-Flux ............................................................................ 83
4.3.5 Transfer of Properties at Interfaces .................................................... 89
4.3.5.1 Lateral Mixing ..................................................................... 89
4.3.5.2 Cloud-Top Entrainment ........................................................90
4.3.5.3 BL Top-Entrainment ............................................................90
4.4 Eddy Diffusivity/Mass-Flux Parameterization in the CBL ............................ 91
4.4.1 The Eddy Diffusivity/Mass-Flux Scheme .......................................... 91
4.4.2 Mass-Flux Contribution ......................................................................94
4.4.2.1 Updraft Model......................................................................94
4.4.2.2 The Mass-Flux Profi le .........................................................96
4.4.3 The K-Diffusion Contribution ............................................................ 98
4.4.4 EDMF-EMP Results ........................................................................... 98
4.4.4.1 Top-Entrainment ................................................................ 100
4.4.4.2 Comparison with Other Approaches ................................. 104
© 2010 by Taylor and Francis Group, LLC