为了评估倾斜对流不稳定的重要性,在加拿大大西洋风暴计划(CASP)期间对七个降水带进行了观测。利用常规和特殊站三小时一次的无线电探空资料,作θ_e~*(饱和相当位温)、M(绝对角动量)和θ_e(相当位温)的垂直剖面和等 M 面分析。等 M、θ_...为了评估倾斜对流不稳定的重要性,在加拿大大西洋风暴计划(CASP)期间对七个降水带进行了观测。利用常规和特殊站三小时一次的无线电探空资料,作θ_e~*(饱和相当位温)、M(绝对角动量)和θ_e(相当位温)的垂直剖面和等 M 面分析。等 M、θ_e和θ_e~*面斜率的比较表明了位势和条件倾斜不稳定的存在。本文主要研究稳定度场的时间演变及其向大气中性状态的调整过程。在七个个例分析中发现了一些一致的结论。证实大气中存在着一个小薄层,它对于条件倾斜对流来说是弱不稳定的,特别是在有显著切变的区域。在高层,位势不稳定通常仅仅维持潜在状态,因为缺少水汽而阻止了能量的实际释放。另一方面,在大气的低层饱和是经常能达到的,因此不稳定性得到释放,导致强降水,这种强降水有时呈多带结构。我们的结果也表明,在饱和区域对于倾斜对流来说大气实际上处于向条件中性状态的调整过程。少于三小时的调整时间与 Emanuel 的快速调整假设是一致的。展开更多
A new finite difference scheme-SCSD scheme has been proposed based on CD (Central Difference)scheme and SUD (Secondr-order Upwind Difference) scheme. Its basic feature is controIlable convectivesfability and always se...A new finite difference scheme-SCSD scheme has been proposed based on CD (Central Difference)scheme and SUD (Secondr-order Upwind Difference) scheme. Its basic feature is controIlable convectivesfability and always second-order accuracy (Stability-Controllable Second-order Difference ). It hasbeen proven that this scheme is convective-stable if the grid Peclet number .The advanage of this new scheme has been discussed based on the modified wavenumber analysis byusing Fourier transform. This scheme has been applied to the 2-D incompressible convective-diffusiveequation and 2-D compressible Euler equation, and corresponding finite difference equations have beenderived. Numerical examples of 1-D Burgers equation and 2-D transport equation have been presentedto show its good accuracy and controllable convective展开更多
文摘A new finite difference scheme-SCSD scheme has been proposed based on CD (Central Difference)scheme and SUD (Secondr-order Upwind Difference) scheme. Its basic feature is controIlable convectivesfability and always second-order accuracy (Stability-Controllable Second-order Difference ). It hasbeen proven that this scheme is convective-stable if the grid Peclet number .The advanage of this new scheme has been discussed based on the modified wavenumber analysis byusing Fourier transform. This scheme has been applied to the 2-D incompressible convective-diffusiveequation and 2-D compressible Euler equation, and corresponding finite difference equations have beenderived. Numerical examples of 1-D Burgers equation and 2-D transport equation have been presentedto show its good accuracy and controllable convective
