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应用非线性振荡理论研究云南局地气温的演变规律 总被引:4,自引:3,他引:1
将描述局地气温变化的非线性振荡方程应用到云南省17个测站局地气温演变研究中,根据各测站1958年1月—2000年12月逐旬气温距平资料和反演理论获得具体描述各测站局地气温变化的非线性振荡方程。以经典非线性振荡理论为依据,研究了云南省17个测站的局地气温演变规律。结果表明,云南局地气温系统是弱的非线性系统;其演变的固有周期大致在6~10旬之间;在无外源强迫的条件下,云南局地气温振幅随时间增加总是衰减;考虑外源强迫的作用后,云南局地气温系统在其演变过程中只随外源强迫的振荡而振荡。应用反演获得的描述各测站局地气温变化的有外源强迫非线性振荡方程做出未来云南局地气温演变趋势预报,其平均预报准确率约为78.9%。说明该模型具有良好的预报能力和预报稳定性。 相似文献
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青藏铁路沿线地面气温演变的非线性振荡规律研究 总被引:1,自引:0,他引:1
将描述局地气温变化的非线性振荡方程应用到青藏铁路沿线9个测站(安多、当雄、托托河、班戈、格尔木、那曲、西宁、拉萨及五道梁)局地年气温演变研究中,根据各测站1966—1997年逐年年气温距平资料和反演理论获得具体描述各测站局地气温的非线性振荡方程。在不考虑外源强迫项的情况下,以经典非线性力学理论为依据,研究青藏铁路沿线9个测站的气温演变规律。结果表明,青藏铁路沿线9个测站局地气温系统是明显的非线性系统,其演变周期大致在3~6年之间,气温振幅随时间增加而衰减。其平均预报准确率为75.4%,有较好的预报能力。 相似文献
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利用多重尺度摄动法,推导出非线性涡旋Rossby波波包的演变方程是非线性Schroedinger方程。对该非线性Schroedinger方程的周期波动解及其稳定性进行了研究,得到了有关稳定和不稳定的判据。数值计算表明:非线性涡旋Rossby波的相速值为10^0m/s量级,这和台风中的螺旋雨带实测移速的量级是一致的,可以从涡旋Rossby波说中较好地解释台风中的螺旋雨带的形成和维持。 相似文献
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利用多重尺度摄动法,对低纬大气Kelvin波和Rossby波的波包演变进行了分析,得到两波的非线性相互作用方程为耦合的非线性复系数Landau方程组。数值计算表明两波相遇将使波振幅变化,波宽变窄;两波非线性相互作用可能是低纬强烈天气突然爆发的原因之一。 相似文献
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1前言大气运动是非常复杂的,其复杂性在数学上表现为非线性。欧阳首承[1]从实际出发,经过多年对流体演化特征和一系列非线性模型的研究和分析,指出在流体运动过程中非线性外迫力可导致原函数的连续性崩溃及逆转;而方程自身的非线性则可导致流体辐合,通过不连续逆转演变为辐散,并称这种过程为溃变,即旧结构的破坏,并通过不连续产生新结构。这种过程正好与天气演变中的转折性变化相对应。Zt意使型图1为概念化的系统演变的模型。fo表示初始时刻,t。表示终极时刻或预报时效,黑点表示一个孤立系统,矢量V可抽象地表示为系统演变方向,… 相似文献
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Guckenheimer和Holmes针对弱受迫系统或如下的小参数受迫方程组 相似文献
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A generalized inverse is presented for the Korteweg–de Vries (KdV) equation, an initial condition and data from synthetic but realistic solitary internal waves. The synthetic data are statistically consistent with hypothesized levels of error in the KdV equation, initial condition and observing system. The observing system consists of point-wise measurements of the pycnocline displacement, either at fixed locations or from a ship drifting in the soliton current. These synthetic inversions are designed using the environmental conditions and disturbances observed by Pinkel [J. Phys. Oceanogr. 30 (2000) 2906]. The inverse solution is found by minimizing a quadratic cost functional, which yields a weighted least-squares best-fit to the KdV equation, the initial condition and the data. The weight for each squared residual is derived from its hypothesized covariance.The minimal value of the least-squares estimator (or cost function) is the test statistic for the error hypotheses and is shown here to be a reliable indicator of grossly incorrect hypotheses. In particular, it will be shown that even with just a single ship survey, the method does lead to decisive tests of hypotheses concerning the level of error in the model. Also, neglect of ship drift is found to be less deleterious to the inversion than is neglect of error in the KdV dynamics.The inverse is calculated by the iterated, direct representer algorithm [Ocean Model. 3 (2001) 137], which is readily extended to include parameter estimation. Significant skill is found for estimating the linear phase speed. 相似文献
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一类奇异孤波解及其在高原低涡结构分析中的应用 总被引:5,自引:0,他引:5
文中利用相平面分析法 ,由非绝热大气运动方程组导出了与非线性重力内波有关的 Kd V方程 ,然后用直接积分法得到两类有意义的孤立波解 ,重点分析了一类具有间断点的奇异孤立波解的特征 ,初步建立了此波解与一类青藏高原暖性低涡的联系 ,讨论了高原加热和层结稳定度对高原低涡生成和移动的影响 ,并且从理论上论证了高原低涡具有与热带气旋类低涡( Tropical cyclone- like vortices)类似的涡眼和暖心结构 相似文献
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非线性正压Rossby波的精确解 总被引:1,自引:0,他引:1
本文从半地转近似下的正压大气运动方程组出发,导出了非线性正压Rossby波所精确满足的KdV方程,求得了椭圆余弦波解和孤立波解,并讨论了非线性波动的波速公式及其振幅与其它波参数间的关系。同时指出,在对大气模式进行数学简化时必须尽可能保证原模式所具有的一些守恒关系,否则有可能使原问题的解受到歪曲。 相似文献
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Starting from the primary equations, the author derives the KdV equation which describes solitary Rossby waves in the tropical atmosphere, and indicates that, because these waves are ageostrophic, they differ from the quasigeostrophic solitary Rossby waves studied by Redekopp et al. Owing to nonlinear action, these waves are also different from traditional linear waves of the tropical atmosphere. The author believes that the stationary tropical atmospheric waves reflect the characteristics of solitary waves in that the energy does not disperse. 相似文献
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Branko Grisogono 《Boundary-Layer Meteorology》1990,52(3):221-225
A simple equation of diffusion is derived from the longwave radiative flux transfer equation for the atmospheric stable nocturnal boundary layer. This simplification is valid with clear-sky conditions, light wind speeds and near the top of the inversion layer which has already been established.The known physical behavior of such a layer in the given conditions (the weak and slow destabilization, and spreading of the top of the inversion layer) is explained by this simple equation of mathematical physics instead of a complicated expression written in terms of the net longwave radiative flux divergence. 相似文献
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《大气和海洋科学快报》2016,(1)
Statistical analysis of turbulent and gusty characteristics in the atmospheric boundary layer under weak wind period has been carried out.The data used in the analysis were from the multilevel ultrasonic anemometer-thermometers at 47 m,120 m,and 280 m levels on Beijing 325 m meteorological tower.The time series of 3D atmospheric velocity were analyzed by using conventional Fourier spectral analysis and decompose into three parts:basic mean flow(period 10 min),gusty disturbances(1 min period 10 min)and turbulence fluctuations(period 1 min).The results show that under weak mean wind condition:1)the gusty disturbances are the most strong fluctuations,contribute about 60% kinetic energy of eddy kinetic energy and 80% downward flux of momentum,although both the eddy kinetic energy and momentum transport are small in comparison with those in strong mean wind condition;2)the gusty wind disturbances are anisotropic;3)the gusty wind disturbances have obviously coherent structure,and their horizontal and vertical component are negatively correlated and make downward transport of momentum more effectively;4)the friction velocities related to turbulence and gusty wind are approximately constant with height in the surface layer. 相似文献
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山地中尺度环流中的大气边界层湍流摩擦效应 总被引:2,自引:0,他引:2
建立了一个三维原始方程数值模式,模拟在光滑下边界和无滑脱下边界两种情况下,山区中尺度环流的演变过程,指出在弱层结条件下,边界层湍流摩擦效应有利于流场的分离和涡旋偶极子环流的发展;在强层结条件下,表面摩擦效应削弱了分离气流和涡旋性环流的强度,但使其范围扩大。边界层湍流摩擦效应引起的分离流场和尾流区环流与非粘性动力过程引起的流场分离现象,虽然从其表现形式上看完全相同,但是其形成则是由完全不同的物理机制所控制。边界层湍流摩擦效应在上述两种分离流场的演变过程中表现出完全相反的作用。地转科氏力的调整作用在山地背风坡上促进了气旋性辐合环流的发展,而抑制了反气旋性环流的发展。 相似文献
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The influence of topography on single-tower-based carbon flux measurements under unstable conditions: a modeling perspective 总被引:1,自引:0,他引:1
Weiguo Wang 《Theoretical and Applied Climatology》2010,99(1-2):125-138
Based on high-resolution numerical simulations, the influence of topography on the one-dimensional (1-D) tower-based measurements of the net ecosystem–atmosphere exchange rate (NEE) of CO2 was analyzed under unstable conditions. Airflow and transport of a passive scalar were simulated over undulating surfaces covered by tall trees. Compared to their flat surface counterparts, the wind and scalar mixing ratio fields are more disturbed over a steeper surface and/or under a weaker background wind condition, resulting in larger errors in the 1-D NEE estimation. The magnitude of the error is generally larger on the windward side than on the lee side when topography-induced circulation (TIC) does not occur. Applying the ensemble streamline coordinate system to estimating NEE could result in larger errors than applying the local earth coordinate system or terrain coordinate system when the atmospheric flow is significantly distorted. This is especially true when TIC occurs. NEE estimated from the 1-D framework under convective conditions with calm or weak background winds may incur significant errors even over gentle topography. Preference in the selection of a flux tower location is given to the crest area. 相似文献