Using satellite altimetry data to augment flow estimation techniques on the Mekong River

Satellite altimetry is routinely used to provide levels for oceans or large inland water bodies from space. By utilizing retracking schemes specially designed for inland waters, meaningful river stages can also be recovered when standard techniques fail. Utilizing retracked waveforms from ERS‐2 and ENVISAT along the Mekong, comparisons against observed stage measurements show that the altimetric measurements have a root mean square error (RMSE) of 0·44–0·65 m for ENVISAT and 0·46–0·76 m for ERS‐2. For many applications, however, stage is insufficient because discharge is the primary requirement. Investigations were therefore undertaken to estimate discharges at a downstream site (Nakhon Phanom (NP)) assuming that in situ data are available at a site 400 km upstream (Vientiane). Two hypothetical, but realistic scenarios were considered. Firstly, that NP was the site of a de‐commissioned gauge and secondly, that the site has never been gauged. Using both scenarios, predictions were made for the daily discharge using methods with and without altimetric stage data. In the first scenario using a linear regression approach the altimetry data improved the Nash‐Sutcliffe r² value from 0·884 to 0·935. The second scenario used known river cross‐sections while lateral inflows were inferred from a hydrological model: this scenario gave an increase in the r² value from 0·823 to 0·893. The use of altimetric stage data is shown to improve estimated discharges and further applications are discussed. Copyright © 2010 John Wiley & Sons, Ltd.     

一种半导体激光天气雷达的波形设计

本文利用霍尔序列设计一种半导体激光天气雷达的发射波形,解决了用m序列时无法解决的信号压缩比要求和系统运算速度限制之间的矛盾。文中给出了波形的设计和产生方法及其性能模拟结果。     

Radar attenuation due to melting: a comparison of physical models proposed for the melting morphology

The radio wave attenuation through the melting layer at various frequencies is investigated. The effect of the melting morphology on the attenuation computed by the Mie theory is discussed. To obtain the rate of melting of snowflakes, a melting model is given. In this model, the six different patterns proposed by Fabry and Szyrmer [J. Atmos. Sci., 56 (1999) 3593] to calculate the permittivity of the melting particles are used and the specific attenuation for each morphology is obtained. A comparison between the computed specific attenuation computed for the frequencies 2.8, 9.4 and 22.2 GHz is made. This analysis suggests that the large variability in the specific attenuation given by these models is due to the melting morphology in which the melting snow is modeled as a snow sphere surrounded by a water shell.     

Results of the first Italian planetary radar experiment

We describe the first intercontinental planetary radar initiative undertaken in Italy.We present the results of the observations of Near-Earth Asteroid (NEA) 33342 (1998 WT24), performed in December 2001 using the bistatic configurations Goldstone-Medicina and Evpatoria-Medicina, with the 32-m Medicina dish used to receive echoes in both cases.The experiment goal was to characterise the system for radar follow-up observations of NEA and artificial orbiting debris, in the framework of a feasibility study which aims at using the Sardinia Radio Telescope, at present under construction, also as a planetary radar facility.     

Monitoring vertical deformation due to water pumping in the city of Paris (France) with differential interferometry

The Saint-Lazare area in Paris (France) has undergone important water pumping for the construction of the underground Haussmann–Saint-Lazare station for the EOLE subway line. This paper presents the monitoring of the small surface displacements related to this pumping activity, by classical SAR interferometry. Piezometric measurements provided on 87 piezometers by SNCF and IGC as well as precise levelling data acquired on 626 points by SNCF are also examined. Their comparison with interferometric results shows their good agreement and complementarity, as well as the potential ‘operationality’ of SAR interferometric approach in such a study. To cite this article: B. Fruneau et al., C. R. Geoscience 337 (2005).     

地质雷达双域数据处理软件及其应用

美国影象有限公司（GeoImage, LLC）开发的“基特\|雷达” （Git\|Radar）软件，既可进行时间域的分析 ，又能直观地在深度域执行反射波振幅或能量的迭加分析.该软件包括一般的二维，三维等绘图支持，且自动化程度较高，普通技术人员经过简单培训即可操作使用.文中给出两个应用实例.     

基于串口控制的人影作业指挥系统

介绍基于RS-232串口控制的人影作业指挥系统的串口通信硬件电路连接、程序结构和地理模型。     

Analysis of heavy rainfall events in North Rhine–Westphalia with radar and raingauge data

Five heavy rainfall events were investigated with radar and raingauge data. Special attention was paid to quality check and adjustment of radar data. Attenuation effects could be observed on both, C-Band and on X-Band radar. Adjustment of radar data to raingauge values turned out to be difficult in the vicinity of heavy local rain cells. Four adjustment methods were analysed and radar data from different radar stations were compared. As a further result of this project, the spatial extent of the precipitation fields was identified by adjusted radar data and compared to raingauge data. For each rainfall event, radar derived accumulated rainfall images and catchment time series were produced.     

乌苏XDR数字化雷达识别雹云指标初探

冰雹是兵团农七师和乌苏市主要灾害性天气之一，常给农业生产造成危害。为了提高防雹作业的效果，1998年对乌苏711雷达进行了数字化改造。作者根据1998～2003年6年回波资料的统计分析，总结出适合本地的识别雹云的指标。     

Statistical evaluation of a radar rainfall system for sewer system management

Urban areas are faced with mounting demands for managing waste and stormwater for a cleaner environment. Rainfall information is a critical component in efficient management of urban drainage systems. A major water quality impact affecting receiving waterbodies is the discharge of untreated waste and stormwater during precipitation, termed wet weather flow. Elimination or reduction of wet weather flow in metropolitan sewer districts is a major goal of environmental protection agencies and often requires considerable capital improvements. Design of these improvements requires accurate rainfall data in conjunction with monitored wastewater flow data. Characterizing the hydrologic/hydraulic performance of the sewer using distant rain gauges can cause oversizing and wasted expenditures. Advanced technology has improved our ability to measure accurately rainfall over large areas. Weather radar, when combined with rain gauge measurements, provides detailed information concerning rainfall intensities over specific watersheds. Knowing how much rain fell over contributing areas during specific periods aids in characterizing inflow and infiltration to sanitary and combined sewers, calibration of sewer system models, and in operation of predictive real-time control measures. Described herein is the design of a system for managing rainfall information for sewer system management, along with statistical analysis of 60 events from a large metropolitan sewer district. Analysis of the lower quartile rainfall events indicates that the expected average difference is 25.61%. Upper quartile rainfall events have an expected average difference of 17.25%. Rain gauge and radar accumulations are compared and evaluated in relation to specific needs of an urban application. Overall, the events analyzed agree to within ± 8% based on the median average difference between gauge and radar.