影响海南岛热带气旋的多层递阶周期分析长期预报模型

使用历年影响海南岛的热带气旋个数作资料样本,在经典多层递阶预报模型的基础上引进多层递阶周期分析,在时间序列自身周期显著的情况下,使用时间序列的显著周期分量取代经典模型中的自回归部份,建立影响海南岛热带气旋的多层递阶周期分析长期预报模型,合理地反映热带气旋影响海南岛的变化规律,提高预报的准确率。     

带周期分析因素的逐步回归方法在寒露风天气预报中的应用

提出以方差分析周期因素嵌入逐步回归建立灾害天气长期预报模型方法，应用结果表明：模型预报精度及稳定性均比单纯的周期分析或利用前期气象因子建立回归模型有明显改善。     

PRESS周期分析及其在粮食产量预报中的应用

作物产量预报常用的统计模型为:Y=Y_t+Y_w+Y_ε。影响作物产量的气象因子的年际间变化存在一定的周期性,因此可采用周期分析法拟合气象产量。所建立的模型具有预报时效长的优点。样本多、周期明显的产量序列其效果更好。本文提出一种用 PRESS 准则提取周期的方法,取名为“PRESS 周期分析”。经使用并与常用的方差周期分析方法进行比较,结果表明,用 PRESS 周期分析建立的预报模型,其历史拟合和试报效果均优于方差周期分     

带周期分析因素的逐步回归方法在寒露风天气预报中的应用

提出以方差分析周期因素嵌入逐步回归建立灾害天气长期预报模型方法，应用结果表明：模型预报精度及稳定性均比单纯的周期分析或利用前期气象因子建立回归模型有明显改善。     

多层递阶周期分析

针对经典多层递阶预报方法的某些不足,提出了一种改进的多层递阶预报模型——多层递阶周期分析。它使用时间序列的显著周期分量取代原模型中的自回归部分,使其更合理地反映气象要素自身的演变规律,有效地提高了预报精度。     

河南省6～8月天气周期划分及应用

利用1991～1995年6～8月500hPa高度场资料,根据河南省6～8份天气特点和影响河南省天气的主要天气系统,划分天气周期,建立天气周期模型.用欧洲中心500hPa高度24、48、72 h预报场,计算出未来3天的平均预报场.把平均预报场与天气周期模型作相似检验,做出未来5天的天气预报.     

逐步回归周期分析与多层递阶方法相结合的时间序列分析预报模型

逐步回归周期分析是针对方差分析的不足而提出的一种时间序列分析方法,作者将其应用于长期预报,取得了一定的效果,但也存在着某些缺陷,其主要表现在实际应用时,随着预报时效的增长,预报效果明显趋于不稳定。这里主要有两个方面的原因:一是某些时间序列本身的周期性不强,所选的周期显著性水平低,此时则不宜单纯用周期分析外推做长期预报,对此,作者已在另文中作过研究。二是在逐步回归周期分析预报模型中,回归系数取为固定的参数,而天气系统则是时变系统。这样,若用固定参数预报模型来描述一个时变参数系统的状态,其拟合率虽然可以很高,但随着预报时效的增     

河南省6—8月天气周期划分及应用

利用1991－1995年6－8月500hPa高度场资料，根据河南省6－8月份天气特点和影响河南省天气的主要天气系统，划分天气周期，建立天气周期模型。用欧洲中心500hPa高度24、48、72h预报场，计算出未来3天的平均预报场。把平均预报场与天气周期模型作相似检验，做出未来5天的天气预报。     

逐步回归双重分析在长期预报中的应用

前言逐步回归双重分析方法运用了逐步回归方法,同时进行因子的筛选和周期分析,在制作预报时,既考虑了前期因子对预报对象的支配作用,又兼顾了预报对象本身周期变化的影响。解决了多元回归和周期分析两种统计方法的不足之处,预报效果较为稳定,预报精度明显提高。一、统计模型的建立气象要素的变化不仅受到前期因子的支配,同时要素本身也有其演变规律,只是在不同的情况、不同的条件下起的作用不同而已。本方法的统计模型为     

月降水量的神经网络混合预报模型研究

以均生函数表征预报量自身周期变化，结合500hPa月平均高度场和月平均海温场预报因子，采用神经网络方法建立了一种新的短期气候预报模型。分别以广西桂北、桂中和桂南6月降水量作为预报对象进行预报试验，结果表明，这种新的预报方法比均生函数回归预报模型及高度场、海温场预报因子的回归预报模型，具有更好的物理基础和预报能力。     

Possible Sources of Forecast Errors Generated by the Global/Regional Assimilation and Prediction System for Landfalling Tropical Cyclones. Part Ⅱ: Model Uncertainty

This paper investigates the possible sources of errors associated with tropical cyclone (TC) tracks forecasted using the Global/Regional Assimilation and Prediction System (GRAPES). In Part I, it is shown that the model error of GRAPES may be the main cause of poor forecasts of landfalling TCs. Thus, a further examination of the model error is the focus of Part II. Considering model error as a type of forcing, the model error can be represented by the combination of good forecasts and bad forecasts. Results show that there are systematic model errors. The model error of the geopotential height component has periodic features, with a period of 24 h and a global pattern of wavenumber 2 from west to east located between 60°S and 60°N. This periodic model error presents similar features as the atmospheric semidiurnal tide, which reflect signals from tropical diabatic heating, indicating that the parameter errors related to the tropical diabatic heating may be the source of the periodic model error. The above model errors are subtracted from the forecast equation and a series of new forecasts are made. The average forecasting capability using the rectified model is improved compared to simply improving the initial conditions of the original GRAPES model. This confirms the strong impact of the periodic model error on landfalling TC track forecasts. Besides, if the model error used to rectify the model is obtained from an examination of additional TCs, the forecasting capabilities of the corresponding rectified model will be improved.     

均值生成函数的周期性延拓在回归分析中存在的问题及其改进方案

针对均值生成函数的周期性延拓在回归分析中存在的回归前提不同,预报因子是预报量的非独立表现等缺点,给出了改进方案。实例分析计算表明：新方案可以有效地消除原方案中存在的非独立虚假相关现象,从而使得筛选出周期性预报因子更加客观。基于本方案所建立的数学预报模型,具有历史拟合率与多步长预报精度基本一致的特点,是一种具有使用价值的长期预报手段,也有一定的隐含周期分辨能力。     

运城市终霜冻预报方法

对运城市终霜冻资料时间序列进行了周期分析，再利用基于预测误差平方和(PRESS)准则的逐步回归周期分析方法建立运城市终霜冻预报模型，预测终霜冻出现的日期，经检验和试报表明，该模型预测效果较好，具有实用价值。     

The role of phase locking in a simple model for glacial dynamics

Glacial–interglacial oscillations are often described by simple conceptual models. Relatively few models, however, are accompanied by analytical solutions, though detailed analytical investigation of climate models often leads to deeper understanding of the climate system. Here we study a simple conceptual model for glacial dynamics, a simplified version of the sea-ice-switch mechanism of Gildor and Tziperman (Paleoceanography 15:605–615, 2000), and provide a detailed analytical treatment for this model. We show that when the model is forced by a simplified insolation forcing it exhibits rich dynamics and passes through a series of bifurcations before being completely phase-locked to the insolation forcing. Our model suggests that even when the glacial cycles are self-sustained, insolation forcing has a major role on the complexity of glacial cycles: (1) it is possible to obtain glacial–interglacial oscillations for a wider parameters range when the amplitude of the insolation forcing is larger; (2) in addition, the ice-volume becomes more periodic; (3) when the period of the ice-volume is minimal the ice-volume is symmetric and for larger period is more asymmetric; (4) the ice-volume can be either periodic, higher order periodic, or quasi-periodic.     

Chaos in a simple model of the three-dimensional, salt-dominated ocean circulation

 A simple moments model used in studying the large-scale thermally driven ocean circulation, in one hemisphere, is extended with a set of evolution equations for the basin-averaged salinity gradients. Natural formulations of the boundary conditions for the heat flux and the (virtual) salt flux are given, the latter based on the SST-evaporation feedback. Stommel’s box model result, a coexisting thermal and saline solution, is retrieved in the limit of no rotation. Including rotation in a salt-dominated setting, a steady circulation is found which bifurcates for higher Rayleigh numbers in a periodic solution which becomes chaotic through a cascade of subharmonic bifurcations. Periodic motion results from two different mechanisms. First, the stable stationary state bifurcates into a periodic solution where anomalously saline water is advected by the overturning circulation. Second, this periodic solution bifurcates into a state which is dominated, during the larger part of the cycle, by diffusion and inertia, characterized by a decreasing overturning rate, and, during the subsequent shorter part of the cycle, by rapid advection and restratification of the entire basin. The basin-averaged vertical density field is stably stratified in the steady and the periodic regimes and remains statically stable in the chaotic regime. Received: 16 July 1996 / Accepted: 29 December 1997     

The perturbed structure of the neutral atmospheric boundary layer over irregular terrain

The differential equations for first-order (linear) response of the planetary boundary layer are formulated for flow over periodic terrain, for variations in both surface roughness and terrain elevation. A simple second-order closure model of the turbulence is used, and Coriolis forces are neglected. Flow over a periodic terrain produces corresponding periodic structure in all meteorological fields above the surface. The periodic structure consists of two components. The first is very nearly evanescent with height. It corresponds to the motion that would be observed were the atmosphere inviscid. The second component, introduced by turbulent viscosity, exhibits a phase variation with height in addition to a decay in amplitude. W.K.B. [Wentzel-Kramers-Brillouin] approximations for the two components are developed, and the coupling between the components is discussed. The formulation for calculating solutions by numerical integration is developed, including specification of appropriate boundary conditions. Calculations are presented in a companion paper.Wave Propagation Laboratory.Environmental Science Group.     

热带大气周期性振荡相图结构与南北半球中纬度热力强迫效应的相关关系

本文根据反映热带大气运动的动力系统数学模型,将热带大气周期性振荡产生条件归纳为动力系统相图椭圆型结构形成问题.本文强调了南北半球中纬度冷暖空气活动对赤道地区热力结构的强迫效应,探讨了此类赤道地区外界热力强迫对热带大气运动周期性振荡形成的作用.本文还讨论了与非周期运动相关的动力系统相图椭圆型结构破坏问题及其相图抛物型、双曲型构成前提条件,并研究了各类相图几何图形特征点与大气运动状态的联系.本文研究还表明,南北半球中纬度冷暖空气活动即使属非周期扰动,若满足动力系统相图椭圆型条件,也可引起赤道地区的高频或低频周期性振荡.     

广西降水量序列的气候变化模型

通过对广西1916年以来的年、季降水量序列进行分析,初步建立了广西降水序列的周期迭加模型、正弦波模型和均生函数模型.     

逐步回归自相关分析

作者从时间序列的自相关分析出发，提出了一种适于回归统计分析的生成预报因子的简单方法，建立起自相关预报模型。实例计算表明，此方法不仅预报精度较高，而且在对周期性相关因子的选择上具有等同的统计、检验前提，避免了一般方法因周期长度不同而带来统计，检验差异的影响。因而得到的回归因子较客观，真实。另外，还具有一定的分析时间序列隐含周期的能力。     

Stochastic Modeling of the Van Lake Monthly Level Fluctuations in Turkey

Summary  Planning, design, construction and operation of lakeshore structures require information about the future likely extremes of the lake levels at a given risk percentage. Alternative future likely synthetic sequences can be numerically generated provided that the underlying generating mechanism of the lake level fluctuation phenomenon is identified. Simple linear and periodic nonlinear models are used for modeling the deterministic part in the lake level records. Linear trend is eliminated from the original lake level historic data by regression line technique. The nonlinear part needs two stages for its identification. First Fourier series is applied to model interannual periodicities in the lake level fluctuation series and then monthly standardization procedure is applied for seasonal periodic nonlinear component modeling. A second order Markov model is found suitable for the remaining stochastic parts. The application of the methodology is presented for the Lake Van monthly level data in eastern Turkey. Suitable models are identified and their parameters are estimated for trend, periodic and stochastic parts. Likely, synthetic lake levels are generated by the stochastic model and hence lake level extreme values are depicted for the next 2, 6, 12, 24, 60 and 120 months with risk calculations. Such risk calculations take into account the stochastic characteristics of the lake level fluctuations only. The deterministic parts as linear trends and periodicities are added to the stochastic extreme events for the actual simulation of the lake levels. The model presented in this paper is not for time prediction of future lake levels but rather for the simulation of possible equally likely extreme lake level value occurrences over any desired future period. Received April 22, 1998/Revised July 28, 1999