Phillips模式的斜压不稳定的非线性饱和问题:能量情形

A conservation law for the Phillips model is derived. Using this law, the nonlinear saturation of purely baroclinic instability caused by the vertical velocity shear of the basic flow in the Phillips model-the case of energy-is studied within the context of Arnold's second stability theorem. Analytic upper bounds on the energy of wavy disturbances are obtained. For one unstable region in the parameter plane, the result here is a second-order correction in ε to Shepherd's; For another unstable region, the analytic upper bound on the energy of wavy disturbances offers an effective constraint on wavy (nonzonal) disturbances φ'i at any time.     

The influence of the coast on the dynamics of upwelling fronts: Part II. Numerical simulations

We investigated the dynamics of upwelling fronts near a coast. This work was first motivated by laboratory experiments [Bouruet-Aubertot, Linden, Dyn. Atmos. Oceans, 2002] in which the front is produced by the adjustment of a buoyant fluid initially confined within a bottomless cylinder. It was shown that cyclonic eddies consisting of coastal waters are enhanced when the front is unstable near the coast (the outer vertical boundary). The purpose of this paper is to provide further insights into this process. We reproduced the experimental configuration using a three-dimensional model of the primitive equations. We first show that for coastal fronts more potential energy, in terms of the maximum available potential energy, is released than for open-ocean fronts. Therefore, waves of larger amplitude are generated during the adjustment and the mean flow that establishes has a higher kinetic energy in the former case. Then as baroclinic instability starts and wave crests reach the boundary, cyclonic eddies are enhanced as in the laboratory experiments and in a similar way. However, in contrast to the laboratory experiments, offshore advection of cyclonic eddies can occur in two stages, depending on the spatial organization of the baroclinic wave. When the baroclinic wave consists of the sum of different modes and is thus highly asymmetric, the offshore advection of cyclonic eddies occurs just after their enhancement at the boundary, as in the laboratory experiments. By contrast, when a single-mode baroclinic wave develops, neighboring cyclonic eddies first merge before being advected offshore. Very different behavior is observed for open-ocean fronts. First a mixed baroclinic–barotropic instability grows. Then the eddies transfer their energy to the mean flow and the barotropic and baroclinic instabilities start again. An excellent agreement is obtained with the main result obtained in the laboratory experiments: the ratio between growth rates of surface cyclonic and anticyclonic vorticity increases as the instability develops nearer to the coast.     

Study on the characteristics of rock failure strain and acoustic emission field for two parallelling faults with the same slip direction including asperities

Introduction Concerning about research on grouped-earthquake seismogenic and occurrence, at present it is only limited on the stage of the theoretical analysis and numerical model. For instance, ZHANG (1987) simulated the grouped-earthquake generation and physical mechanism making use of spring-block principle. Applying for non-linear dynamic model, referring to Chinese continental plate as object, LI, et al (1997) performed the numerical simulation on the seismogenic and occurring of group…     

基于高温高压岩石破裂实验结果对中强地震前震中附近区域部分地震学现象的初步解释

依据高温高压岩石破裂实验结果并结合理论分析，对 附近区域不同深度温压条件下岩石变形破坏性质及破坏失稳的力学行为进行了研究，在一次应力加载循环中，发生破坏的部位随时间具有向深部下迁的趋势。考虑到深度温压条件下岩石的渐进式破坏行为及突发失稳，对主震前震中附近区域小地震活动的增强、平静、活化等现象，以及b值等时间序列参数变化的可能机理进行初步探讨，并简单讨论了两类平静和两类b值变化的可能原因。     

地球流体力学的研究与进展

简要介绍中国科学院大气物理研究所七十多年来在理论与计算地球流体力学方面的若干研究及其新的进展.在理论地球流体力学方面,介绍了长波动力学及线性稳定性问题、弱非线性理论及行星波动力学以及用Arnold方法(能量-Casimir方法)研究大气和海洋中各种流体运动的非线性稳定性问题的成果.此外,对扰动演变、扰动和基流相互作用及热带大气动力学中的第二类不稳定条件(CISK)也作了简要的介绍.在计算地球流体力学方面,主要内容包括:用物理观点和数学分析相结合的方法阐述了造成计算紊乱和计算不稳定的机理,论证计算稳定性、算     

一次区域性大暴雨环境特征分析

通过对冀东南、鲁西北一次区域性大暴雨的分析表明：除有利的大尺度环流背景以外，超低空急流是大暴雨不稳定能量和水汽的主要输送者，高能区不稳定能量释放，产生大暴雨所需的强烈上升运动。暴雨落区与超低空急流前部最大风速切变区的位置密切相关。     

长江流域一次暴雨过程中的不稳定条件分析

文中分析了 1998年 7月 2 0～ 2 3日发生于长江流域的持续性降水和暴雨过程 ,在分析大尺度降水和中小尺度暴雨相对应的环流场和天气实况的基础上 ,主要分析相应大气层结的对流不稳定和条件性对称不稳定条件 ,并对切变线上涡层不稳定做了重点介绍和分析 ,计算了条件性对称不稳定判据和涡层不稳定判据。结果表明 :降水期间大气低层有对流不稳定和对称不稳定能量的积聚 ,在这两类不稳定条件都基本满足的情况下 ,涡层不稳定的维持对此次降水过程中暴雨的发生提供了有利的不稳定环境场 ,具体的计算分析还表明环境场的配置制约着切变线上低涡扰动的发展 ,是造成降水的重要原因之一。     

A Comparative Study of the Atmospheric Layers below First Lifting Condensation Level for Instantaneous Pre-Monsoon Thunderstorm Ocurence at Agartala(23°30′N,91°15′E) and Ranchi(23°14′N,85°14′E) of India

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非均匀层结下的对称不稳定

研究了非均匀层结下的对称不稳定，给出了不稳定发生的判据，并将该微分方程的特征值问题化为一个实对称矩阵的特征值问题，还取不同的层结廓线进行了数值计算。     

HLAFS和T63数值预报产品在暴雨分析中的应用

首次使用ＨＬＡＦＳ数值预报产品对黑龙江省暴雨进行分析，结合Ｔ６３数值预报产品，利用两者提供的物理一０８时和２０时的实况场和预报场格点资料，对黑龙江省一次暴雨过程进行分析，找出了暴雨发生的物理机制，指出深厚的水汽条件以及水汽的辐合，强烈的上升运动和不稳定能量的存贮和释放是产生暴雨的关键因素。