西北太平洋温带气旋爆发性发展的热力-动力学分析

DYNAMICS/THERMDYNAMICS DIAGN0SIS OF EXPLOSIVE DEVELOPMENT OF EXTRATROPICAL CYCLONES OVER THE NORTHWESTERN PACIFIC OCEAN

利用天气、位涡分析和导出的Lagrangian型广义Z－O发展方程的诊断分析，考查了两个西北太平洋温带气旋爆发件发展的主要强迫机制和热力一动力空；司结构。结果表明，热力强迫对爆发性气旋发展起主要控制作用，当反映大气斜乐性的Laplacian温度平流、积云对流和湍流加热为主的热力强迫共同作用使地转相对涡度急剧增长时，气旋便出现了爆发性发展，其中积二尺度的对流加热贡献更大。Laplacian绝热冷却、大气向海洋的感热输送和摩擦效应起阻滞发展的作用，也是控制气旋衰亡的主要过程。爆发性发展启动同子因例而异，涡度平流、Laplacian温度平流和Laplacian大尺度加热均可成为主要启动因子。垂直积分平均分布和垂直结构考查进一步佐证了诊断分析的结果，并揭示了气旋爆发性发展过程中一些重要的热力-动力学分布特征。

Both the primary forcing mechanisms and dynamical/thermdynamical distributions oftwo explosive cyclones over the Northwestern Pacific Ocean were investigated using synopticmeteorology, potential vorticity dynamics and Lagrangian generalized Z-O equation diagnosis. The results demonstrated that thermodynamical forcing dominated the explosive development of marine cyclones, i. e. explosive development occurred as Laplacian temperatureadvection reflecting the baroclinicity of atmosphere, Laplacian cumulus heating and turbulent heating combined to force significant geostrophic vorticity increases while more contributions resulted from Laplacian cumulus heating. Dynamical forcing of vorticity convectionplayed relatively small role while explosive development progressed. The primary thermodynamical forcing processes that acted to inhibit development were the sensible heat transferfrom air to sea and the adiabatic cooling whereas the dynamic forcing process that exerted aconsistently strong damp influence was the friction dissipation. Moreover, the three primaryforcing processes also resulted in the much slower development or decay of cyclones. Theinitiation factors that triggered the explosive development of cyclones differed between thetwo cases. Either the vorticitycaconvection or both temperature convection and large-scalecondensation heating can drive to initiate the explosive development of cyclones. The examinations of integrated-averaged distribution and vertical structure of dynamical/thermodynamical forcing terrns revealed further some important dynamical/thermodynamical distribution characteristics.