我国可能最大暴雨洪水研究的进展

我国的暴雨洪水大、人口众、土坝多。为了保障人民生命财产和工农业的安全,许多大型、重要的中小型水库多采用可能最大暴雨洪水作为设计、校核的标准。在水文与气象人员的协作下,我国近十年来的可能最大暴雨与洪水计算方法得到一定的发展,提出了具有中国特色的方法、论文和一些专著,并开始了国际交流。本文综述这方面的进展并提出了几点看法。     

区域海气耦合模式FROALS模拟的西北太平洋环流及其年际变率

本文利用区域海气耦合模式FROALS(Flexible Regional Ocean-Atmosphere-Land System)对西北太平洋地区1984-2007年连续积分结果,对比SODA(Simple Ocean Data Assimilation)同化资料讨论了西北太平洋海表温度和表层洋流的气候态及年际变率。结果表明,FROALS基本能够再现冬、夏季季节平均的海温型,但均存在一个明显的冷偏差;FROALS对气候平均态的表层洋流有较高的模拟技巧,对于冬、夏季的表层洋流型都能够再现。另外,表层洋流的模拟偏差与海表高度的模拟偏差直接相关。由于模式模拟的黑潮热输送较观测偏强,使得模式模拟的海洋热输送倾向于使黑潮路径上的海温呈现正偏差。从表层洋流的年际变率来看,模式模拟的与ENSO(El Nio-South Oscillation)相联系的年际变率信号与观测相似:在El Nio年,北赤道流和棉兰老流增强,低纬度西太平洋海表高度降低,而在La Nia年则呈现出相反的形态,但是在模式中这种信号稍强于观测。     

��ظ�ԭ���������쳣�ĵ����춯��ѧ�о�

???????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????о??????? ????????????????????????????????б?′?????????????????????????????????????????????????     

利用SLR计算地心运动方法研究

Three methods for calculation of geocenter motion are intruduced.     

Risk evaluation of China’s natural disaster systems: an approach based on triangular fuzzy numbers and stochastic simulation

To deal effectively with the evaluation problem of natural disaster risk system affected by many uncertain factors, a multivariate connection number expression is presented. This expression is based on the index samples and evaluation grade criterions of natural disaster risk system and is capable of describing the hierarchy property and fuzziness of membership relationship between index samples and evaluation grade criterions. In this proposed method, the fuzzy evaluation grade criterion problem is resolved by combining triangular fuzzy numbers with multivariate connection number theory, and triangular fuzzy numbers are used to express the discrepancy degree coefficients of connection number and evaluation index weights. Accordingly, a connection number-based evaluation method for the natural disaster system of China (named CN-TFN for short) is established using triangular fuzzy numbers and stochastic simulation. The application results show that the spatial distribution of natural disaster risk grades of China has the trend of aggrandizement from west to east of China. The economically developed and densely populated coastal areas are very likely to have a high level of natural disaster risk grade or above; thus, these areas are the key regions of the natural disaster risk management of China. The results also show that the CN-TFN is able to reflect practical conditions of the evaluation problem of natural disaster system and to provide more reliability information as compared to the existing evaluation methods. This is as a result of its comprehensive usage of various information of subjective and objective uncertainties in the evaluation process of natural disaster risk system and its expression by confidence intervals. Due to the simplicity and generalization, the CN-TFM is applicable to comprehensive risk grade evaluation of various natural disaster systems.     

氚分析在某些库坝地区深岩溶及渗漏问题研究中的应用

近二十年来,对于深岩溶和岩溶渗漏问题的研究,采用了一种利用氚作为天然示踪剂的新方法。本文以乌江渡、猫跳河四级水电站为例,根据地下水的氚含量,确定深岩溶发育的部位,利用氚等值线进行岩溶渗漏带的划分。     

中国与澳大利亚的气象合作

中国与澳大利亚的领土面积很接近,跨越经度大致相同,所处纬度数也差不多,但是人口、历史和社会结构则有极大差异。在过去的十五年间,两国合作迅速发展,作为人类活动中必然进行国际合作的领域之一——气象更是如此。本文简单地对比了两国气象发展的历史和目前状况,并概述了1985年两国开展双边气象合作以来所执行的项目的主要内容。     

DIAGNOSIS ON LOW FREQUENCY COMPONENT OF ENSO VARIABILITY—PART Ⅱ:ORIGIN OF THE COMPONENT

Diagnosis is undertaken on the origin for the low-frequency component (LFC) of ENSOvariability in the context of 1979—1990 OLR and u-wind datasets.Evidence suggests that ① apower spectrum-yielded maximum,significant statistically,is derived from the OLR monthlyanomalies in a 3—5-year period range over the tropical central/western Pacific;②compositeanalysis of the signals of the monthly anomaly low frequency component (period>3 years)confirms further the dynamic features of the component as documented in Part Ⅰ:③serving asforcing on ENSO,the related monsoon region represents the source area of the component;④theone-point correlation maps of unfiltered OLR monthly anomalies with zonal wind on a lagged,asimultaneous and a leading basis show clearly the close relation between the u wind-associatedeastward travelling low-frequency wave and the low-frequency oscillation of low-latitude central/western Pacific large-scale convection and the east-moving mode is likely to be excited by theoscillation at a 3—5-year period range.It follows that the large-scale convection oscillation showsup as the origin of the eastward waves,i.e.,ENSO LFC.     

热带印度洋海温的年际变化与ENSO

文中讨论了热带印度洋海表温度距平空间分布的年际变化与赤道中东太平洋海温的关系。EOF分析的结果表明 ,印度洋海温的变化主要存在全区符号一致的单极型和西部与东南部符号相反的偶极型 ,它们具有显著的年际变化。小波凝聚谱揭示了单极、偶极的变化与Nino3区海表温度距平存在密切关系 ,印度洋海温距平从偶极到单极的变化对应着ElNi no事件从发展到衰减的过程。平均而言 ,印度洋偶极超前Nino3区海温距平约 4个月 ,单极滞后约 6个月。整个热带印度洋 -太平洋地区海气耦合特征的演变表明 ,与ElNino从发展到衰减相联系的热带西太平洋海气耦合相互作用在印度洋海温距平从偶极到单极的演变过程中起着非常重要的作用。     

On the growth of disturbances to forced and dissipated barotropic flows

Abstract

We consider the growth of disturbances to large-scale zonally-asymmetric steady states in a truncated spectral model for forced and dissipated barotropic flow. A variant of the energy method is developed to optimize the instantaneous disturbance energy growth rate. The method involves solving a matrix eigenvalue problem amenable to standard numerical techniques. Two applications are discussed. (1) The global stability of a family of steady states is assessed in terms of the Ekman damping coefficient r. It is shown that monotonic global stability (i.e., every disturbances energy monotonically decays to zero) prevails when r≥r_c . (2) Initially fastest-growing disturbances are constructed in the r<r_c regime. Particular attention is paid to a subregion of the r<r_c regime where initially-growing disturbances exist despite stability with respect to normal modes. Nonlinear time-dependent simulations are performed in order to appraise the time evolution of various disturbances.