CONTENTS

1. INTRODUCTION 1


2. HYDRODYNAMICS 5


2.1. Basic Model Equations 5

2.2. Overview of the Spectral Technique 10

2.3. The Spectral Form of the Model's Equations 15

2.4. The Time Integration Scheme 21

2.5. Normal Modes Initialization 25

APPENDIX 2A
THE ARAKAWA VERTICAL FINITE DIFFERENCING SCHEME
33


3. RADIATION 43


3.1. Preprocessing Input Data 43

3.2. Climatological Input Data 44

3.3. Shortwave Processes 45

3.4. Longwave Processes 53

Figure 3.1 | Figure 3.2 | Figure 3.2 Caption | Figure 3.3 | Figure 3.4 | Figure 3. 5 | Figure 3.5 Caption |

4. ATMOSPHERIC BOUNDARY LAYER AND PROCESSES AT THE EARTH'S SURFACE 74


4.1. Purpose of Subroutine PROGTN 74

4.2. The Computation of Surface Temperature 89

4.3. Evapotranspiration Over Land 101

APPENDIX 4A
CHANGES TO THE SURFACE LAYER'S
MONIN-OBUKHOV
FORMULATIONS OF MOMENTUM,
HEAT, AND MOISTURE
FLUX
109


5. PRECIPITATION AND DIFFUSION PROCESSES 138


5.1. Vertical Diffusion 138

5.2. Shallow Convection 142

5.3. Deep Convection 144

5.4. Grid-scale Condensation 147

6. GRAVITY WAVE DRAG PARAMETERIZATION 150


6.1. Introduction 150

6.2. Basic Formulation 150

6.3. Program Implementation and Coding Considerations 154

7. SURFACE BOUNDARY DATA 159


(figures are not present)

7.1. Land/Sea Specification 159

7.2. Orography 159

7.3. Sea Surface Temperature 159

7.4. Surface Roughness 159

7.5. Subsurface Soil Temperature 159

7.6. Surface Albedo 160

7.7. Sea Ice Distribution 160

7.8. Soil Moisture 160

7.9. Snow Depth 160

7.10. Sea Surface Temperature Adjustment 160

8. USER'S GUIDE TO THE FORECAST MODEL 191


8.1. Introduction 191

8.2. Programs 191

8.3. Input and Output 192

8.4. Resolution and Wavenumber Truncation 211

8.5. Flow Charts 213

8.6. Other Programs 223

9. Additional Numerical Techniques 234


9.1. Horizontal Diffusion 234

9.2. Time Scheme for Ground Temperature and Vertical Diffusion 242