1:10 000基础测绘数字产品的质量控制     

夏荣 《测绘与空间地理信息》2007,30(2):167-168

从生产实际出发,对1:10000基础测绘数字产品DLG,DEM,DOM,E00质量控制的主要内容和方法进行了较全面的阐述,并提出了一些影响测绘产品质量的问题。  相似文献   

GRACE和SLR观测的地球动力学扁率最大熵谱及小波相关分析          下载免费PDF全文

张子占  陆洋  许厚泽 《地球物理学报》2007,50(5):1383-1389

卫星重力测量技术的实现为测定地球动力学扁率提供了新的方式和途径，GRACE卫星是目前最新的重力测量卫星，据其恢复的低阶重力场较以往精度得到大大提高，然而其观测地球动力学扁率（二阶项）却与卫星激光测距（SLR）结果相差较大.本文采用最大熵谱和小波分析方法对GRACE和SLR观测的地球动力学扁率时间序列信号进行定量比较分析，结果表明：GRACE观测的地球动力学扁率年际周期变化振幅仅为SLR观测结果的25%，并且目前GRACE观测的地球动力学扁率数据中含有系统输入信息和相位差，但前者较后者包含有较强的短周期（2～6月）信息.造成这种差异的主要原因可能来自于GRACE与SLR全球观测数据时空分布不同.  相似文献   

Outgoing long wave radiation variability from IR satellite data prior to major earthquakes   总被引：12，自引：1，他引：12  

Dimitar Ouzounov  Defu Liu  Kang Chunli  Guido Cervone  Menas Kafatos  Patrick Taylor 《Tectonophysics》2007,431(1-4):211

Our analysis of the continuous outgoing long wave earth radiation (OLR) indicates anomalous variations prior to a number of medium to large earthquakes. The most recent analysis of OLR is from the M9.0 Sumatra Andaman Islands mega trust event. We compared the reference fields for December 2001 to 2004 and found OLR anomalous values, > 80 W/m², (2σ) within the epicentral area on Dec 21, 2004, 5 days before the event. We used the NOAA/IR daily (one degree) and monthly (two and half degree) gridded data to differentiate between the global and seasonal variability and the transient local anomalies. The cause of such anomalies is not fully understood; one possible explanation is the existence of thermal outgoing radiation as a result of near ground air ionization and latent heat change due to change of air humidity and temperature. This phenomenon is hypothesized to be part of a relationship between tectonic stresses, electrochemical and thermodynamic processes in the atmosphere and increasing mid IR flux, all part of a family of electromagnetic (EM) phenomena related to earthquake activity. The time scale of the observed variations is a few weeks before the onset of the seismic event. In comparison with several years of data, the observed time-series preceding the earthquake had unusually high OLR. The OLR anomaly corresponds to a large area of ground coverage and coincides with the main epicentral zone. The significance of these observations is explored using data from most recent East Asian earthquake swarm of December 2004 and three other earthquakes.  相似文献   

一次局地冰雹的新一代天气雷达回波演变特征分析     

谢向阳  张平文  刘臣亮 《沙漠与绿洲气象(新疆气象)》2007,1(5):42-43

2004年5月31日20时40分至21时15分,兵团农六师芳新垦区出现了一次局地冰雹天气,冰雹直径为0.5～0.8cm,但冰雹密度大,致使芳草湖农场353hm2棉花受灾。本文应用雷达的二次产品及回波特征对局地冰雹的发展、演变进行分析,对发展迅速的局地冰雹云的雷达识别和准确预报冰雹落区是有意义的。  相似文献   

闽西一次冰雹过程的雷达产品分析   总被引：1，自引：1，他引：1       下载免费PDF全文

刘君肖秀珠  张红梅徐竹泉 《气象科技》2007,35(B12):86-88,93

以闽西一次典型冰雹过程为例，对这次冰雹过程的雷达基本反射率和基本速度特征进行了定性分析，对回波强度、回波顶高、强回波核高度、垂直积分液态含水量和多普勒速度等进行了定量分析。通过分析发现了一些冰雹雷达产品的重要指标和判据，这些结论在龙岩市日常的天气预报业务工作中对判断是否为冰雹回波和降雹时段、地点有很好的作用。  相似文献   

Testing satellite and ground thermal imaging of low-temperature fumarolic fields: The dormant Nisyros Volcano (Greece)   总被引：1，自引：0，他引：1  

E. Lagios  S. Vassilopoulou  V. Sakkas  V. Dietrich  B.N. Damiata  A. Ganas 《ISPRS Journal of Photogrammetry and Remote Sensing》2007,62(6):447-460

The Nisyros Volcano (Greece) was monitored by satellite and ground thermal imaging during the period 2000–2002. Three night-scheduled Landsat-7 ETM⁺ thermal (band 6) images of Nisyros Island were processed to obtain land surface temperature. Ground temperature data were also collected during one of the satellite overpasses. Processed results involving orthorectification and 3-D atmospheric correction clearly show the existence of a thermal anomaly inside the Nisyros Caldera. This anomaly is associated mainly with the largest hydrothermal craters and has land surface temperatures 5–10 °C warmer than its surroundings. The ground temperature generally increased by about 4 °C inside the main crater over the period 2000–2002. Ground thermal images of the hydrothermal Stephanos Crater were also collected in 2002 using a portable thermal infrared camera. These images were calibrated to ground temperature data and orthorectified. A difference of about 0–2 °C was observed between the ground thermal images and the ground temperature data. The overall study demonstrates that satellite remote sensing of low-temperature fumarolic fields within calderas can provide a reliable long-term monitoring tool of dormant volcanoes that have the potential to reactivate. Similarly, a portable thermo-imager can easily be deployed for real-time monitoring using telemetric data transfer. The operational costs for both systems are relatively low for an early warning system.  相似文献   

导航卫星原子钟频率漂移特性分析   总被引：2，自引：0，他引：2  

郭海荣  杨生  何海波 《全球定位系统》2007,32(6):5-10

介绍了原子钟频漂定义，总结了频率漂移率测试评定方法，比较分析了不同噪声情况下的频率漂移率估计方法，并用实验室真空状态铷钟的频率偏差数据和GPS卫星钟的精密星历数据进行了计算分析，表明铷钟都有明显频漂，GPSIIR铷钟的日漂移率在10^-15。量级，而铯钟频漂不是很明显。研究了频漂对原子钟时域稳定性影响规律，还利用模拟数据进行了计算分析。验证了方法的有效性．  相似文献   

德国降水预报产品的应用和检验     

巴哈古丽  赵战成 《沙漠与绿洲气象(新疆气象)》2007,1(4):27-30

利用德国降水预报输出的24和48h降水预报产品,对2005年1—12月巴音郭楞蒙古自治州(简称巴州,下同)9个气象站分别进行了降水预报效果的检验分析,统计分析其在各月、各季、年的降水预报能力,得出其空报率较大,准确率和漏报率较低,但对巴州南部地区的大降水天气有一定的指导意义。  相似文献   

雷暴云电结构与闪电关系初探   总被引：1，自引：13，他引：1       下载免费PDF全文

罗霞  陈渭民  李照荣  胡胜娟  李旭 《气象科学》2007,27(3):280-286

利用雷暴云偶极性电结构理论,结合卫星和雷达资料分析了不同荷电结构下地面电场。结果表明:当正电荷中心高度越高、负电荷中心高度越低,形成的地面负电场越大,越有利于地闪的形成;负地闪发生后或云砧下方,地面电场成正极性,易引发正地闪;地闪分布与雷达回波、卫星云图中雷暴云位置基本一致,结合雷达和卫星资料可初步判断正/负地闪发生位置。  相似文献   

Near real-time estimation of Sea and Land surface temperature for MSG SEVIRI sensors     

《International Journal of Applied Earth Observation and Geoinformation》2020

Land and Sea Surface Temperatures (LST and SST) are both recognized as Essential Climate Variables, and are routinely retrieved by a wealth of satellites. However, for validated approaches, the latest data are usually not available to the general public. We offer to bridge this gap, by using Meteosat Second Generation (MSG) Spinning Enhanced Visible and InfraRed Imager (SEVIRI), with its 15 min temporal resolution. Here, we present generic algorithms for the retrieval of both LST and SST, valid for the SEVIRI instrument onboard MSG platforms 8–11, which we validate using hourly data of 4 ground stations and 11 buoys in Spain over the years 2015 to 2018. These validations show that in the best conditions of surface homogeneity (cloud-free summer nights), errors in our LST estimation are below 1.5 K for stations with good thermal homogeneity. Comparison with LSA-SAF (Land Surface Analysis - Satellite Application Facility) LST shows differences below 2 K for most of SEVIRI disk, with higher differences in arid areas and during daytime. As for SST retrieval, the average error amount to 0.67 K for cloud-free buoy data. These algorithms have been implemented in a near-real time processing chain, which provide actualized LST and SST maps every 15 min within 5 min of image reception. These maps, along with other products, can be freely consulted from a dedicated webpage (https://www.uv.es/iplsat).  相似文献