The Effect of Back-Reflection in the Parameterization of Non-Orographic Gravity-Wave Drag
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چکیده
An efficient method of solution is developed for the Warner and McIntyre parameterization of the drag associated with nonhydrostatic non-orographic inertia–gravity waves. The scheme is sufficiently fast as to enable, for the first time, fully interactive multi-year climate simulations that include the effects of rotation and nonhydrostatic wave dynamics in the parameterization of non-orographic gravity wave drag. It is found that the new scheme alleviates much of the middle-atmosphere wind biases that occur in the Canadian Middle Atmosphere Model when either of its two operational hydrostatic non-orographic gravity wave drag parameterizations are used. The dominant effect of including this extra dynamics in the parameterization comes from the nonhydrostatic process of back-reflection. The results indicate that, depending on its azimuthal direction, the momentum flux launched into the stratosphere at midlatitudes can be reduced by as much as 75% due to back-reflection. The momentum flux launched into the stratosphere at tropical latitudes, however, is relatively unaffected by back-reflection. This has important implications for the forcing of tropical oscillations such as the semi-annual oscillation and the quasi-biennial oscillation in general circula-
منابع مشابه
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تاریخ انتشار 2002