GIS中地籍宗地面积的方差分量估计

探讨在地籍宗地数字化的面积处理问题中,把已知面积数据和数字化坐标同时作为观测值的面积处理方法.采用方差分量估计,解决已知面积数据参与平差时的权的确定.通过实例分析,认为采用条件平差方差分量估计方法来对宗地面积处理,能够更加合理地调整已有面积与由数字化坐标得到的面积值之间的差异.     

Helmert方差分量估计的粗差检验与抗差解

当观测值中含有粗差时，检验表明Helmert方差分量估计结果同样含有粗差，且粗差还可能会发生转移，为有效地抵制粗差和随机模型差的互相影响，指出了发生这一转移的原因，介绍了基于双因子等价权的抗差估计，并针对相关Helmert方差分量估计抗差解求解过程中容易出现的法矩阵0值溢出问题，提出了改进方法。     

相关稳健估计及其在测量数据

在对现有的基于等价权的稳健估计的弊端进行分析的基础上,直接从方差膨胀模型出发,建立起一套基于调整观测量方差-协方差阵的相关稳健估计方法,并通过算例证明其估计思想、模型的正确性和可行性.     

Measured And Simulated Latent And Sensible Heat Fluxes At Two Marine Sites In The Baltic Sea

In this study, turbulent heat flux data from two sites within the Baltic Sea are compared with estimates from two models. The main focus is on the latent heat flux. The measuring sites are located on small islands close to the islands of Bornholm and Gotland. Both sites have a wide wind direction sector with undisturbed over-water fetch. Mean parameters and direct fluxes were measured on masts during May to December 1998.The two models used in this study are the regional-scale atmospheric model HIRLAM and the ocean model PROBE-Baltic. It is shown that both models overestimate the sensible and latent heat fluxes. The overestimation can, to a large extent, be explained by errors in the air-water temperature and humidity differences. From comparing observed and modelled data, the estimated 8-month mean errors in temperature and humidity are up to 1 °C and 1 g kg^-1, respectively. The mean errors in the sensible and latent heat fluxes for the same period are approximately 15 and 30 W m^-2, respectively.Bulk transfer coefficients used for calculating heat and humidity fluxes at the surface were shown to agree rather well with the measurements, at least for the unstable data. For stable stratification, the scatter in data is generally large, and it appears that the bulk formulation chosen overestimates turbulent heat fluxes.     

江苏省夏季持续干旱和雨涝的气候分析以及环流和海温场演变特征

在对我省夏季持续干旱和雨涝进行气候分析的基础上，研究了夏季持续干旱和持续雨涝的环流特征差异、持续干旱的两种不同的环流型以及前期海温场的特征和演变规律。     

一个改进的湍流垂直扩散过程参数化方案

研究了数值天气预报模式中次阿格湍流垂直扩散过程的参数化问题。以Ｂｏｕｇｅａｕｌｔ和Ｌａｃａｒｒｅｒｅ（１９８９）的参数化方案为基础，改进了处理湍流混合长的方法，使湍流混合长和热力混合长分别依赖于基本气流的静力稳定度和风场切变。新方案的基本思路是把ＶｏｎＫａｒｍａｎ（１９３０）提出的动力（风场切变）湍流扰动假设与ＢＬ－８９方案提出的热力（静力稳定度）湍流扰动假设结合在一起，强调了大气的热力结构、动力结构和湍流动能对湍流混合过程的共同影响。新方案和ＢＬ－８９方案的二维对比数值试验结果表明，在大气处于静力较稳定而风场切变明显条件下的湍流扰动表现能力方面，新方案比原方案有明显的改进。     

我国草原下垫面低层大气湍流结构

利用超声风速仪资料分析了科尔沁草原下垫面低层大气的湍流谱结构，无量纲化湍流速度分量及温度脉动的标准偏差，和湍流通量与稳定度参数的关系。结果表明，草原下垫面低层大气湍流速度谱，在较宽的稳定度范围内， 符合Kolmogorov 相似理论，在惯性副区接近局地各向同性，无量纲化湍流速度分量及温度脉动的标准偏差服从A(1-Bζ)1/3和A(-ζ)-1/3规律， 湍流热通量与稳定度参数ζ存在较好的相关性。     

东亚大气环流的低频振荡及与韵律的关系

本文根据北半球500hPa高度场30年(1951—1980)平均的逐候格点资料,对气候平均的东亚各主要大气环流系统的年内变化进行了谐波分析和天气学分析.结果表明,东亚大气环流系统存在着三种主要的大气低频波:年波、半年波和30—50天的季内波;中、高纬度的大气环流以年波振荡为主,低纬度的大气环流以半年波振荡为主;30—50天的季内波是北半球各纬度上都存在的一种波,但它对总方差的贡献在低纬比中、高纬度大.此外,还讨论了年波和半年波这两种大气低频波与我国长期预报中常用的各种韵律指标特别是隔季相关现象的关系.     

Textural analysis and modelling of a flood deposit: River severn,U.K.

Samples of sediment collected from the Severn floodplain between Worcester and Gloucester following the severe flooding in January and February 1990, were analysed for their grain size distribution. The results show that most sand was deposited within 20 m of the channel bank, but that fine sand may contribute to flood sediment across the width of the floodplain. James' (1985) numerical model of overbank sedimentation attempts to predict the transfer of sediment to the floodplain during flooding. Geometrical and hydraulic data relating to the Severn flood are used as input for a computer program of James' (1985) model. The pattern of sediment concentrations predicted by the model was compared with that obtained from statistical analysis of the flood sediment. The patterns were found to be similar, so James' (1985) model was considered to predict in a relative sense the distribution of flood sediment.