NUMERICAL EXPERIMENTS OF THE INFLUENCE OF DIABATIC HEATING ON TROPICAL CYCLONE ASYMMETRIC STRUCTURE

Using the barotropic volticity equation that contains forcing from diabatic heating with appropriate parameterization. a number of numerical experiments are conducted for the tropical cyclone that is initially symmetric The result shows that the diabatic heating has important effects on the asymmetric structure in addition to the roll of the β term and nonlinear advection term in its formation. It again confirms the conclusion that the diabatic heating is a possible mechanism responsible for such structures in the tropical cyclone.

DYNAMICAL STUDY OF DIABATIC HEATING INFLUENCE ON RADIAL INHOMOGENEOUS STRUCTURE OF TROPICAL CYCLONE

Based on the tropical cyclone(TC)asymmetric disturbance as the superposition of the symmetric environmental circulation,the analytical solution of travelling wave is given by using the barotropical nondivergent model with diabatic heating forcing and non-friction in a plane polar coordinate.Then,the TC radial inhomogeneous structure is analyzed on radial/tangential velocity and geopotential height.It is found that the different kinds of structures are influenced by the Coriolis parameter(f),TC intensity(Ω),disturbance circular frequency(ω),and TC angular wavenumber(m).And,the diabatic heating(Q_1)has significant impacts on the radial/tangential velocity distribution shaped like the inner-tight and outer-relaxed.

Effect of Horizontal Nonuniformity of Diabatic Heating on Tropical Cyclone Intensity and Structure

The effect of the horizontal variation of diabatic heating on the tropicalcyclone intensity and structure is studied in this paper. According to the potential vorticity (PV)equation in axis-symmetric cylindrical coordinates, PV disturbance caused by the radial differenceof diabatic heating is positive (negative) inside (outside) the maximum heating radius, implyingthat the radial nonuniformity of diabatic heating should contribute positively to the intensity of atropical cyclone while negatively to its size. A primitive equation model is then used to get somequantitative ideas on the problem. Results show that the modeled tropical cyclone weakens by about20% but is larger in size if the effect of horizontal variety of convective heating is excluded inthermodynamic and dynamic equations. The PV disturbance originated from the horizontal nonuniformityof diabatic heating is positive inside the maximum heating radius and negative outside, inconsistent with the PV equation analyses. The maximum disturbance (both negative and positive)appears around the maximum heating level and their magnitude is comparable to that generated byvertical variance of heating. It is concluded that the effect of the horizontal heat nonuniformityon the intensity and structure of TC cannot be neglected.

非绝热加热对热带气旋径向非均匀结构的影响

利用平面极坐标系下无摩擦有外源（非绝热加热）的正压无辐散方程，将热带气旋的物理量分解成环境场和扰动，进而求出了热带气旋扰动的行波解，并分析了风场（切向、径向）和重力位势扰动场的径向非均匀松紧结构．表明：这种松紧结构与热带气旋所在纬度的科氏参数（f）、热带气旋的强度（Ω）、热带气旋扰动的圆频率（ω）、热带气旋扰动在θ方向的角波数（m）有关，且不同要素的松紧结构不尽相同；同时还受非绝热加热（Q1）的影响，这种影响主要表现在使风场（切向、径向）呈内紧外松的非均匀分布．

非绝热加热对热带气旋非对称结构影响的数值试验

利用含非绝热加热强迫的正压涡度方程。将非绝热加热作适当的参数化处理，对初始对称结构的热带气旋作了一系列数值试验，结果表明：不仅β项、平流项在热带气旋非对称结构的形成中有重要作用，而且非绝热加热对热带气旋的非对称结构亦有重要影响，从而验证了非绝热加热是热带气旋非对称结构形成的一种可能机制的结论。