Application of FY-2C Cloud Drift Winds in a Mesoscale Numerical Model     

LI Huahong  WANG Man  XUE Jishan  QI Minghui 《Acta Meteorologica Sinica》2010,24(6):740-748

Statistical tests and error analysis of cloud drift winds(CDWs) from the FY-2C satellite were made by using radiosonde observations.According to the error characteristics of the CDW,a bias correction using the thermal wind theory was applied in the data quality control.The CDW data were then assimilated into the GRAPES-meso model via the GRAPES-3DVar.A torrential rain event that occurred in northwestern China during 1-2 July 2005 was simulated.The results indicate that the CDW data were mainly distribute...  相似文献   

Integration of remote sensing data into hydrological models for reservoir management     

C. LOUMAGNE  M. NORMAND  M. RIFFARD  A. WEISSE  A. QUESNEY  S. LE HÉGARAT-MASCLE 《水文科学杂志》2013,58(1):89-102

Abstract

The purpose of this paper is to present the methodology set up to derive catchment soil moisture from Earth Observation (EO) data using microwave spaceborne Synthetic Aperture Radar (SAR) images from ERS satellites and to study the improvements brought about by an assimilation of this information into hydrological models. The methodology used to derive EO data is based on the appropriate selection of land cover types for which the radar signal is mainly sensitive to soil moisture variations. Then a hydrological model is chosen, which can take advantage of the new information brought by remote sensing. The assimilation of soil moisture deduced from EO data into hydrological models is based principally on model parameter updating. The main assumption of this method is that the better the model simulates the current hydrological system, the better the following forecast will be. Another methodology used is a sequential one based on Kalman filtering. These methods have been put forward for use in the European AIMWATER project on the Seine catchment upstream of Paris (France) where dams are operated to alleviate floods in the Paris area.  相似文献   

联合平差中大地测量观测值的数学模型     

单杰 《武汉大学学报(信息科学版)》1988,(4)

本文引入了摄影测量与非摄影测量观测值联合平差中大地测量观测值的严密数学模型——三维大地测量模型和常规的近似模型,针对这两种模型的局限性,提出了适合于联合平差的准三维大地测量模型。  相似文献   

南极拉斯曼丘陵地区大地测量控制网   总被引：1，自引：0，他引：1       下载免费PDF全文

陈春明  鄂栋臣  桑吉章 《极地研究》1995,7(3):101-106

南极拉斯曼丘陵地区大地测量控制网的建立与施测前后共历经４年方始完成，总控制面积约１７７．６平方公里。本文主要讨论了该网分区布设情况及总体平差的原理与方法，并对成果进行了统计分析。经过整体平差的结果可以满足１：１００００测图的需要。该网也是我国东南极中山站地区的基础大地控制网  相似文献   

方差的边缘极大似然估计     

周世健 《武汉大学学报(信息科学版)》1993,(2)

测量平差问题中,方差估计理论是复杂的。本文基于概括模型,组成自由项f(极大似然估计 MLE)的密度函数和改正数向量 V的线性函数(边缘极大似然估计 MMLE)的密度函数,详细推导了函数模型与随机模型中,未知参数 X与σ_0~2 的似然估计公式,分析了基于两种密度函数所得σ_0~2的似然估计存在差异的真正原因,并对两种方法所得的σ_0~2和X 的统计性质进行了讨论。指出边缘极大似然估计,σ_0~2 的具有良好的统计性质,可改善极大似然估计σ_0~2 的不定性(有偏);并且对任一平差模型的边缘极大似然估计,σ_0~2 无偏、有效的统计性质是一致的。  相似文献   

方差分量估计的MINQE理论及其在摄影测量中的应用     

樊启斌 《武汉大学学报(信息科学版)》1990,(2)

本文深入研究了异方差分量模型的MINQE(U,I)准则的算法实现的可能性,所导出的约化算法具有压缩内存,提高运算速度等明显优点,因而具有实用意义。文中介绍了实现约化算法的计算机程序框图,并提供了数据例子。作者将方差分量估计的MINQE理论引入解析摄影测量平差实践,分别采用模拟数据和新滩滑坡监测数据研究了自检校光束法平差中随机模型的确定,结果表明,MINQE理论用于自检校的验后权估计是可行的。最后,作者就平差随机模型的扩展,以及MINQE理论的应用提出了进一步研究的几点设想。  相似文献   

地壳垂直形变模型的研究     

刘权威 《武汉大学学报(信息科学版)》1990,(3)

本文重点研究了建立整个形变区域的形变速率曲面和形变加速率曲面,同时也研究了求这两种曲面的方法(基于多元逐步回归分析的间接法和直接法),从而使我们对整个形变区域有一个形变的整体概念,也使我们能方便地得出形变区任何一个已知其平面位置的点在任一观测期内的形变量。  相似文献   

Test of Hack's slope to bed material relationship in the Southern Eifel Uplands,Germany     

Rolf Schruder 《地球表面变化过程与地形》1991,16(8):731-736

The local reach gradient of small gravel bed rivers (drainage area 0-8-110 km²) in the Eifel, West Germany, is adjusted to transport the river bed sediments. Transport of gravel becomes possible under high flow conditions (Shields entrainment factor ≈-03). Mean bed material size for riffle sections increases with distance downstream. For small drainage areas channel slope is a negative exponential function of drainage area, while for the larger region the additional influence of bedload size has to be considered. Good agreement with Hack's data (1957) for Virginia and Maryland, U.S.A., is achieved (S = 0.0066 (D₅₀/A)^{- 40.}, r = 0.67).  相似文献   

THE　RIVER　CHANNEL　ADJUSTMENT　AS　INFLUENCED　BY　THE　FLOODPLAIN　GEOECOSYSTEM：　AN　EXAMPLE　FROM　THE　HONGSHAN　RESERVOIR     

XU Jiongxin  SHI Changxing 《国际泥沙研究》1994,(3)

ＴＨＥＲＩＶＥＲＣＨＡＮＮＥＬＡＤＪＵＳＴＭＥＮＴＡＳＩＮＦＬＵＥＮＣＥＤＢＹＴＨＥＦＬＯＯＤＰＬＡＩＮＧＥＯＥＣＯＳＹＳＴＥＭ：ＡＮＥＸＡＭＰＬＥＦＲＯＭＴＨＥＨＯＮＧＳＨＡＮＲＥＳＥＲＶＯＩＲ￥ＸＵＪｉｏｎｇｘｉｎ；ＳＨＩＣｈａｎｇｘｉｎｇ（Ｐｒ...  相似文献   

BAYES方差分量估计在虚拟权平差中的应用     

覃辉 《四川测绘》1994,17(3):110-114

本文把近似Bayes方基分量估计公式应用于矿区扩建网的虚拟权平差中，解决了具体计算中的一些实际问题，最后，通过一矿区扩建网平差实例验证了该方法的可行性．  相似文献