Meteorological Bulletin
 
 
Keywords:      Physical parametrization,
               radiation, vertical diffusion,
               gravity wave drag,
               moist convection, stratiform
               precipitation, soil processes
 
 
                             RESEARCH MANUAL 3
                            ECMWF FORECAST MODEL
                          PHYSICAL PARAMETRIZATION
 
                          ECMWF Research Department
 
 
2/84   Original Version
1/88   2nd Edition
7/91   3rd Edition
 
 
CONTENTS
 
 
Table 1 List of constants and symbols
 
 
                                 CHAPTER 1
                                 Overview
 
1.1  INTRODUCTION
 
1.2  OVERVIEW OF THE CODE
 
 
                                 CHAPTER 2
                                 Radiation
 
2.1  RADIATIVE HEATING
 
2.2  LONGWAVE RADIATION
 
    2.2.1       Vertical integration
    2.2.2       Spectral integration
    2.2.3       The incorporation of the effects of clouds

2.3  SHORTWAVE RADIATION

    2.3.1       Spectral integration
    2.3.2       Vertical integration
    2.3.2.1     Cloudy fraction of the layer
    2.3.2.2     Clear-sky fraction of the layers
    2.3.3       Multiple reflections between layers
    2.3.4       Cloud shortwave optical properties
 
2.4  HORIZONTAL INTERPOLATION
 
2.5  INPUT TO THE RADIATION SCHEME
 
    2.5.1       Model variables
    2.5.2       Clouds
    2.5.3       Aerosols
    2.5.4       Carbon dioxide and ozone
    2.5.5       Ground albedo
    2.5.6       Solar zenith angle
 
2.6  THE RADIATION CODE
 
    2.6.1       Definition of constants
    2.6.2       Main routines
    2.6.3       Specialized routines
    2.6.4       Heating rate computation
 
     REFERENCES (CHAPTER 2)
 
                                     CHAPTER 3
               Vertical diffusion and interaction with the surface
 
3.1  THEORY
 
    3.1.1      Basic equations
    3.1.2      Surface fluxes
    3.1.3      Definition of the transfer coefficients over land
    3.1.4      Transfer coefficients over sea
    3.1.5      Definition of the exchange coefficients
    3.1.6      Definition of the top of the boundary layer
    3.1.7      Kinetic energy dissipation
 
 
3.2  CODE:    Subroutine VDFMAIN

    3.2.1      Preliminary computation
    3.2.2      VDFSURF
    3.2.3      VDFEXCS
    3.2.4      VDFEVAP
    3.2.5      VDFHEIGHT
    3.2.6      VDFEXCU
    3.2.7      VDFDIFM and VDFDLFH
    3.2.8      VDFINCR
    3.2.9      VDFSDRV
    3.2.10     VDFT2M
 
 
     REFERENCES (CHAPTER 3)
 
 
                                     CHAPTER 4
                                 Gravity wave drag
 
4.1  THEORY
 
    4.1.1      The formulation of the scheme
 
4.2  CODE:      Subroutine GWDRAG
 
    4.2.1      Preliminary computations (GWSETUP)
    4.2.2      Tw(Ps) [GWSTRESS]
    4.2.3      The profile of stress Tw [GWPROFIL]
    4.2.4      The tendencies.
    4.2.5      Diagnostics
    4.2.6      Implicitness

     REFERENCES (CHAPTER 4)
 
 
 
                                    CHAPTER 5 
                                    Convection
 
5.1  CUMULUS CONVECTION
 
    5.1.1     Large-scale budget equations
    5.1.2     Cloud model equations
    5.1.2.a   Penetrative convection
    5.1.2.b   Shallow convection
    5.1.2.c   Midlevel convection
    5.1.3     Discretization of the model equations
    5.l.4     Melting of snow
    5.1.5     Evaporation of rain
 
5.2  STRATOCUMULUS
 
5.3  CODE
 
     REFERENCES (CHAPTER 5)
 
 
                                     CHAPTER 6
                             Stratiform precipitation 
 
6.1  THEORY
 
    6.1.1     Definition of the saturation specific humidity
    6.1.2     Equilibrium values T*, q* at saturation, starting
              from T and q
    6.1.3     Derivative of qsat (T,p)  with respect to T
    6.1.4     Evaporation of precipitation
    6.1.5     Melting of snow

6.2  CODE:     Subroutine COND
 
6.3  REMOVAL OF NEGATIVE MOISTURE VALUES: subroutine QNEGAT
 
     REFERENCES (CHAPTER 6)
 

                                     CHAPTER 7
                                   Soil processes 
 
7.1  THEORY
 
    7.1.1     Sea points
    7.1.2     Land points
    7.1.2(a)  Temperature
    7.1.2(b)   Moisture
    7.1.2(c)   Snow
    7.1.2(d)  Snow melting
    7.1.2(e)  Time-stepping
 
7.2  CODE:     Subroutine SURF
 
     REFERENCES (CHAPTER 7)
 
 
                                  APPENDIX 1
 
                     Climatological data used in the model
 
1.    OROGRAPHY
 
2.    LAND-SEA MASK
 
3.    ROUGHNESS LENGTH
 
4.    ALBEDO
 
5.    DEEP-LAYER SOIL TEMPERATURE
 
6.    DEEP-LAYER SOIL MOISTURE
 
7.    VEGETATION
 
8.    OZONE DISTRIBUTION
 
      REFERENCES