Development of a cumulus parameterization scheme based on a new static stability criterion

本文利用观测资料和数值实验资料，从虚拟温度湿绝热减速率的角度探讨了饱和气团在非饱和环境下的稳定性理论的有效性，并提出了一种新的积云对流参数化方案。观测结果与理论吻合较好。在数值实验中，我们考虑了一个由地表热通量、水平平流和大尺度沉降之间的平衡维持的积云边界层。即使外力是固定的，也会出现两种平衡状态。一种是有组织对流状态，另一种是随机分布的无组织对流状态。两种状态的边界层特征如温度垂直梯度是不同的。为了研究对流的稳定性，我们必须考虑这两种状态之间的差异。

The purpose of this work is to investigate the validity of the stability theory of a saturated air parcel in an unsaturated environment in terms of the moist adiabatic lapse rate of virtual temperature using observational data and numerical experiments data, and to develop a new parameterization scheme of cumulus convection. Observational results show a good agreement with the theory.For the numerical experiment, we consider a cumulus boundary layer maintained by the balance between the surface heat fluxes, horizontal advection, and large-scale subsidence. Even if the external forcing is fixed, there occur two balanced states. One is the state with organized convection and the other is the state with randomly distributed non-organized convection. The characteristics of the boundary layer such as vertical gradient of temperature is different between the two states. In order to investigate the stability of convection, we must consider the difference between the two states.