基于IGS超级跟踪站的近实时GPS气象研究及应用

目前国内许多城市开始将CORS综合应用网服务于气象部门,为给地基GPS气象研究人员提供一个真实的研究环境,本文基于IGS超级跟踪站网络搭建了一个近实时GPS气象系统,并结合实测数据验证了该系统的有效性。基于该平台可以系统地研究GPS遥感水汽、层析水汽三维分布、数值天气预报同化GPS水汽以及利用电离层分布进行空间天气预报等理论。     

Estimation for partially observed Markov processes

Many stochastic process models for environmental data sets assume a process of relatively simple structure which is in some sense partially observed. That is, there is an underlying process (X_n, n 0) or (X_t, t 0) for which the parameters are of interest and physically meaningful, and an observable process (Y_n, n 0) or (Y_t, t 0) which depends on the X process but not otherwise on those parameters. Examples are wide ranging: the Y process may be the X process with missing observations; the Y process may be the X process observed with a noise component; the X process might constitute a random environment for the Y process, as with hidden Markov models; the Y process might be a lower dimensional function or reduction of the X process. In principle, maximum likelihood estimation for the X process parameters can be carried out by some form of the EM algorithm applied to the Y process data. In the paper we review some current methods for exact and approximate maximum likelihood estimation. We illustrate some of the issues by considering how to estimate the parameters of a stochastic Nash cascade model for runoff. In the case of k reservoirs, the outputs of these reservoirs form a k dimensional vector Markov process, of which only the kth coordinate process is observed, usually at a discrete sample of time points.     

A heuristic model for potential geomorphic influences on trophic interactions in streams

Whereas certain linkages between stream channel morphology and stream ecology are fairly well-understood, how geomorphology influences trophic interactions remains largely unknown. As a first step, a simple, heuristic model is developed that couples reach-scale geomorphic morphology with trophic dynamics between vegetation, detritus, herbivores, and predators. Predation is assumed to increase with depth beyond a threshold depth, and herbivory is assumed to decrease with velocity beyond a threshold velocity. Results show that the modeled food chain is sensitive to channel geometry, particularly around the threshold conditions for predators and herbivores. Importantly, geomorphic influences are not isolated to a particular trophic level, but rather are transferred through the food chain via top-down and bottom-up effects. The modeled system is particularly sensitive to changes in the end-members of the food chain: vegetation and predators. Results illustrate that geomorphic disturbances, known to affect a single trophic level (e.g., fish), likely impact multiple trophic levels in the stream ecosystem via trophic interactions. Such impacts at the multiple trophic level are poorly understood. While limited by the lack of empirical long-term data for testing and calibration, this simple model provides a structure for generating hypotheses, collecting targeted data, and assessing the potential impacts of stream disturbance or restoration on entire stream ecosystems. Further, the model illustrates the potential for future coupled stream models to explore spatial and temporal linkages.     

RESEARCH OF THE INHOMOGENEITY TEST OF CLIMATOLOGICAL DATA SERIES IN CHINA*

Some achievements on the inhomogeneity test of climatological data series and some correlative conclusions were described,from which we concluded that it was very necessary to test the homogeneity of the Chinese climatological data series.Many techniques on this field developed by foreign experts are suitable for Chinese climatological series,and the main factors for the inhomogeneity of the Chinese climatological data are the relocation of stations and the change of instruments.     

黄河上游梯级水电站施工洪水优化设计方法探讨--以黄河公伯峡水电站施工洪水优化设计为例

梯级水电站设计洪水方法一直是梯级水电站水文设计的难点．几十年来在黄河上游梯级电站设计中已总结出一套比较完整的设计洪水及施工洪水计算方法。通过黄河公伯峡水电站施工洪水优化设计过程，论述了该套方法．并就目前存在的一些观点及疑问给予了较为明确的回答。     

澜沧江某水电站左岸地下式厂房岩体质量分级

通过大量的现场调查数据与统计工作结果，采用了多种岩体质量分级评价方案，对澜沧江某水电站左岸地下式厂房岩体质量进行了精细的评价，最后将各种结果进行对比分析，得到一个合理、科学的综合岩体质量综合评价分级。并根据评价结果，作出了研究区坝址左岸地下式厂房岩体在不同高程的岩体质量分区图，为下一步的参数选取工作奠定了必要的基础。     

四川雅安地质灾害时空预警试验区初步研究

借鉴美国旧金山湾和香港地区的经验,提出了地质灾害监测预警试验区建设和研究思路。经过近两年的工作,初步建成了四川雅安地质灾害监测预警试验区。取得的阶段性成果主要有:(1)根据现场考察和试验区地质灾害数据库,统计研究了降雨型滑坡的几何特征;(2)建成了由20台遥测雨量计构成的降雨观测网,取得了2002年4月～2003年8月的降雨观测数据;(3)结合历史降雨资料分析,初步研究了雅安试验区的年、日、小时和十分钟最大降雨特征;(4)研制了斜坡岩土体含水量野外监测仪,取得了桑树坡试验点2003年4月～8月的实时监测数据;(5)自上而下分4层研究了斜坡岩土层含水量变化,发现了岩土层含水量变化对降雨过程的滞后性;(6)基于区域地质灾害评价预警的递进分析理论与方法(AMFP),利用地质灾害因子分析结果,分别计算了雅安试验区地质灾害"发育度"和"潜势度";(7)利用2003年8月23～25日的过程降雨观测资料,对雅安试验区在该降雨过程中发生的地质灾害事件进行了时空预警反演模拟研究,计算出的地质灾害"危险度"分布比较符合实际,"危险度"可以作为预警指数使用。     

人工免疫系统在梯级水库群短期优化调度中的应用

免疫起源于抗感染的研究,是一种机体识别和排斥抗原性异物的生理功能。现代仿生技术将免疫应用到解决非线性优化问题中,形成了独特的人工免疫系统(AIS),AIS用抗体代表问题的可行解,用抗原代表问题的约束条件和目标函数,采用期望繁殖率来定义父体选择的概率进行随机搜索全局最优解。将AIS应用到梯级水库群短期(日)优化调度的研究中,经过对某梯级水库群的仿真计算,认为其结果是合理和可实际应用的。     

青藏高原地区大气加权平均温度模型的构建

加权平均温度(Tm)是将天顶湿延迟转换为大气可降水量的关键参数,针对青藏高原地区海拔高、地形起伏大、水汽高度分布复杂的特点,本文利用2010—2014年GGOS Atmosphere Tm格网数据和地表高程数据建立Tm垂直递减率函数,进而建立一种顾及Tm垂直递减率变化的适合青藏高原地区的新模型(QTm模型).此外,利用...