A Scheme to Retain the Hadley Circulation During Nonlinear Normal Mode Initialization

Abstract

A modified nonlinear normal mode initialization scheme is proposed which provides a possible solution to a major problem associated with nonlinear normal mode initialization. The modified scheme retains the Hadley circulation in the model and at the same time eliminates the gravity wave oscillations. The main feature of the modified scheme is that it isolates model normal modes which are significantly affected by convective processes and excludes these from the initialization by the application of a low-frequency cut-off. The modified scheme has obvious application to four-dimensional assimilation of data.