包含超梯度力作用的台风次级环流诊断方程

次级环流在台风的发展和维持中起着重要作用，基于梯度风平衡的Sawyer Eliassen（SE）方程常用于台风次级环流的诊断。然而梯度风平衡关系在台风边界层及边界附近有较大误差，这导致SE方程求解出的次级环流在边界层也会有较大误差。本文在梯度风平衡方程中保留包含径向摩擦力项在内的超梯度力项，得到包含超梯度力作用的SE方程，从方程形式上看超梯度力主要是通过调节与斜压性相关的系数来影响次级环流的。对“森拉克”（2008）台风次级环流的诊断结果显示，在不人为改变边界层流场结构的情况下，新的SE方程能显著改善次级环流的求解效果，避免眼墙外侧边界层附近的虚假对流并且减小虚假入流。

A Supergradient Force Included Diagnostic Equation for Secondary Circulation of Typhoon

Secondary circulation plays an important role in the intensifying and maintenance of typhoon. The Sawyer Eliassen (SE) equation derived based on gradient wind balance is usually used to diagnose the secondary circulation of typhoon. However, the gradient wind balance has large errors within and near the boundary layer, which leads to large errors of the secondary circulation solved by SE equation within the boundary layer. Based on the full formation of the radial momentum equation, a novel SE equation is derived in this paper. The supergradient force including the radial friction of boundary layer is therefore considered in the novel SE equation. And it turns out that the supergradient force can modulate the secondary circulation by affecting the coefficients related to baroclinicity in SE equation. The diagnostic analysis of the typhoon Sinlaku (2008) shows the novel SE equation can improve the solved secondary circulation remarkably without subjective modifying the flow structure near boundary layer. The novel SE equation can avoid the false convection at the out flank of the eyewall in and near the boundary layer, and can reduce the false strong boundary layer inflow.