Normal mode initialization for simple models

Summary The normal mode initialization procedures of Phillips (1960) and Temperton (1988) are re-examined and applied to one-dimensional linear and non-linear primitive equations models. The linear method is obtained by setting the first and second substantial time derivatives of the divergence to zero. The resulting state is free of gravity waves. In the non-linear procedure, the substantial time derivatives calculated from the model equations of the gravitational modes are set to zero by implicitly adjusting these modes only. Five-day numerical integrations are performed using both models. The results clearly show the importance of proper initialization. Analytical solutions support the numerical results.With 2 Figures