DOES WIND STRESS DEPEND ON SEA-STATE OR NOT? – A STATISTICAL ERROR ANALYSIS OF HEXMAX DATA

There have been several claims, either explicit or by implication, either based on experimental evidence or on theoretical reasoning, that the wind stress is modified by the stage of development of the wind sea. However, the overall evidence is weak, because theories are still incomplete and because it is questionable whether the sea-state effect, which is of the order of 10%, can be separated from experimental noise, which is of the order of 20%. In this paper a rigorous statistical analysis of HEXMAX data is pursued in order to establish the significance of sea-state effects. It appears that the enhanced drag, especially at high winds, which has already been established by previous analyses, cannot be attributed to the effect of young waves. The analysis provides no clues for the actual mechanism, which could be related to breaking or shoaling waves. As the effect of sea-state on wind stress is much smaller than the experimental noise level, it is hard to detect. Nevertheless, HEXMAX seems to contain a wave effect that is at the edge of statistical significance. It is, however, not the wave age itself that influences the drag, but a parameter involving wave height.Because the HEXMAX evidence is only indicative, we conclude that the issue set out in this paper cannot be answered on the basis of the HEXMAX data alone. It is recommended that error analyses are also carried out for other relevant observational data sets and that new measurements with suppressed noise will be taken up.     

Multiresolution Flux Decomposition

Geophysical variables are orthogonally decomposed by averaging timeseries using different averaging lengths, referred to as a (Haar)multiresolution decomposition. This simple and economic decomposition isassociated with cospectra that formally satisfy Reynolds averaging rules foreach averaging length. The multiresolution decomposition provides a naturalestimate of the random error in estimating a mean turbulent flux. The Fourierand multiresolution decompositions are compared using aircraft data fromBOREAS.     

用卡尔曼滤波预报南海热带气旋路径的试验

利用卡尔曼滤波方法预报南海热带气旋路径，发现采用卡尔曼滤波可以大大地降低预报误差，提高预测模型的预报能力。     

古洪水流量的误差计算

古洪水研究已在大型工程和长江三峡，黄河小浪底等的设计洪水中得到动用取得了令人虚心成功，但古洪水流量的推求与实测量的计算往往有大的差别，根据随机误差的传播给出了一般情况下的古洪不流量推误差计算公式，以小流底２３６０ａＢＰ古洪水注同误差的计算为例，对最终计算出的古洪水流量成果给出了一个误差范围。     

水库流域入库洪水预报误差分析

由于受水库枢纽工程的影响，使得反推计算的入库流量本身就存在较大的误差，从而增加了入库洪水预报模型研制的难度，影响了这时预报精度的考核。通过对全国诸多水电厂水库流域实时洪水预报的实践，对其入库洪水预报中存在的误差原因及解决方法进行了科学的分析和阐述，以指导实时预报。     

西南极菲尔德斯GPS形变网监测数据的误差特性分析与处理

本文对西南极菲尔德斯形变网ＧＰＳ监测数据的误差特性进行分析，利用数理统计原理检验了数据中的系统误差，提出了削弱这类系统误差的方法。该方法有３个特点：１．以监测网中两个稳定点为基准；２．对监测网数据进行尺度因子改正与坐标变换迭代计算；３．归算后监测网点位结构不变。经改化处理后的数据，基本上消除了系统误差的影响。     

灰色预测模型在径流长期预报中的应用

基于灰色系统的建模理论，利用河西地区有关河流的径流观测资料，建立了一个ＧＭ（１，１）残差序列周期修正径流预测模型，并用于春旱缺水期３～６月河流来水量的长期预报，经生产部门验证，准确率在８０％以上     

地球物理反问题中的随机反演理论

本文从最大后验概率密度观点出发，在数据噪音向量和待求模型向量为具有零均值的独立高斯随机过程的假设前提下，建立起了随机反演的非线性系统方程；给出了模型方差估计的函数表达式，并在文章最后，证明了反演解的稀疏性，即解释了随机反演的输出解的高分辨率特征。文章在最小二乘反演方法的基础上，发展并完善了随机反演方法的理论基础；揭示了随机反演方法与最小二乘反演方法之间的本质区别；阐述了随机反演方法的优越性，并指出了其广阔的应用前景。     

ADVANCES IN MEASURING TECHNIQUES OF BED LOAD

I.m~UCrIONBedloadisthesedimentwhichmovesalongtheriverbedintheformofrolling,slidingandsaltation.BedloadmaycreatemanyproblemsintheoperationandmaintenanceofnavigationchannelandinthedevelOPmentofhydroelectricity.Dataofbedloaddischargearealsorequiredinthedesignofreservoir,inwhichtheinflowbedloadareallactuallytrapped.Thewaysofbedloadmotionaredifferentfordifferentsizes.Thus,itisextremelydifficulttodeterminethebedloaddischargeaccurately.Manyequationshavebeenproposedtocalculatethebedloaddischarge.H…     

数据采集中特征点粗差定位方法的探讨

本文分析了特征点应满足的几种条件，给出了一次范围最小（Ｌ１）法，最小二乘法以及粗差探测法进行特征点粗差定位方法，并以模拟实例为例对它们进行了比较，得出了一些有意义的结论。