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21.
林连溪 《测绘与空间地理信息》2014,(9):201-203
高度测量可以用水准测量、三角高程测量、数字化直接测量等多种测量方法,当前由于结构复杂的建构筑物日益增多,对于这类建构筑物的高度测量中,不一定都能顺利施测,常用的测量方法显示出其局限性。本文以对中国女排三连冠纪念碑碑高测量为例,介绍了一种新的高度测量方法——两站测角高度测量法。 相似文献
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引发广西两次严重山洪地质灾害的暴雨过程分析 总被引:2,自引:0,他引:2
利用常规观测、卫星云图、雷达探测以及自动站雨量等资料,对2010年6月27—28日和2012年5月20—22日桂西北两次严重山洪地质灾害的气象条件进行了对比分析,结果表明:(1) 强降雨发生在桂西北暴雨区,最大过程雨量>350 mm,过程最大中尺度雨团和致灾区最大中尺度雨团值分别>100 mm·h-1和>70 mm·h-1,集中降雨时段为02—06时。灾害开始于后半夜,发生在最大过程雨量和地质条件脆弱区,不同的地质状况对应不同的灾害;灾害性天气具有区域小、降雨时段集中、过程雨量大、强度强及引发灾害重等特征。(2) 暴雨发生在欧亚地区500 hPa呈两脊一槽型、200 hPa南亚高压脊线贯穿广西上空及季风云系活跃的背景下。高空为槽或低涡、地面为干线或锋面,属低涡暴雨型。(3) 高空要素变化为雨前降压升温、后降温。不稳定能量及层结、低层辐合、中低层涡旋、整层大气的上升运动、高温高湿及水汽强烈辐合是物理量特征。(4) 云图上对流云团生成、合并对强降雨有指示意义,暴雨发生在云团合并发展阶段;TBB值<200 K可以作为强降雨的指标。低质心强雷达回波产生的列车效应或回波停滞和地形作用是造成强降雨的重要因素,低层辐合、高层辐散导致了强烈的上升运动,有利于强对流的发展与维持。 相似文献
23.
文章利用察右中旗2010年人工观测与自动仪器观测的对比分析,分析两种观测技术获取的气象数据所存在的差异,确保结果的科学性,为自动站业务化运行和气候资料的连续性提供一定参考依据。 相似文献
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Reference evapotranspiration (ETo) is a key component in efficient water management, especially in arid and semi-arid environments. However, accurate ETo assessment at the regional scale is complicated by the limited number of weather stations and the strict requirements in terms of their location and surrounding physical conditions for the collection of valid weather data. In an attempt to overcome this limitation, new approaches based on the use of remote sensing techniques and weather forecast tools have been proposed.Use of the Land Surface Analysis Satellite Application Facility (LSA SAF) tool and Geographic Information Systems (GIS) have allowed the design and development of innovative approaches for ETo assessment, which are especially useful for areas lacking available weather data from weather stations. Thus, by identifying the best-performing interpolation approaches (such as the Thin Plate Splines, TPS) and by developing new approaches (such as the use of data from the most similar weather station, TS, or spatially distributed correction factors, CITS), errors as low as 1.1% were achieved for ETo assessment. Spatial and temporal analyses reveal that the generated errors were smaller during spring and summer as well as in homogenous topographic areas.The proposed approaches not only enabled accurate calculations of seasonal and daily ETo values, but also contributed to the development of a useful methodology for evaluating the optimum number of weather stations to be integrated into a weather station network and the appropriateness of their locations. In addition to ETo, other variables included in weather forecast datasets (such as temperature or rainfall) could be evaluated using the same innovative methodology proposed in this study. 相似文献
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R. Pillet D. Rouland G. Roult D. A. Wiens 《Physics of the Earth and Planetary Interiors》1999,110(3-4):211-234
Direct earthquake-to-station Rayleigh and Love wave data observed on high gain broadband records are analyzed in order to improve the lateral resolution of the uppermost mantle in the southwest Pacific region. We used data of nine permanent Geoscope and Iris stations located in the southern hemisphere and nine other stations as part of two temporary networks, the first one installed in New Caledonia and Vanuatu (hereafter named Cavascope network) by ORSTOM and the EOST from Louis Pasteur University in Strasbourg (France) and the second one installed in the Fiji, Tonga and Niue islands (hereafter named Spase network) by Washington University in St. Louis (USA). In order to collect more significant details on the surficial structures, we included the analysis of short period waves down to 8 s. A multiple frequency filtering technique has been used to recover phase velocities of Rayleigh and Love waves for selected earthquakes with magnitude greater than 5.5 and with known centroid moment tensor (CMT). About 1100 well-distributed seismograms have been processed in the period range 8–100 s and corrections for topography and water depth have been applied to the observed phase velocities. The geographical distribution of phase velocity anomalies have then been computed using the tomographic method developed by Montagner [Montagner, J.P., 1986a. Regional three-dimensional structures using long-period surface waves. Ann. Geophys. 4 (B3), 283–294]. Due to a poor knowledge of dense, well-distributed, crustal thickness values and corresponding velocity models, we did not perform or speculate on the construction of an S-wave 3D velocity model; therefore, we limited this study to the interpretation of the phase velocity distribution. The location of phase velocity anomalies are well determined and the deviations are discussed within the framework of the geological context and compared with other tomographic models. At long periods, from 40 s to 100 s, our results agree well with most of previous studies: the tomographic imaging shows a large contrast between low and high phase velocities along the Solomon, New Hebrides and Fiji–Tonga trenches. The lowest phase velocity anomalies are distributed beneath northern and southern Fiji basins and the Lau basin (corresponding to the volume situated just above the dipping slabs), whereas the highest values are displayed beneath the Pacific plate and the eastern part of Indian plate downgoing under the North Fiji basin. At shorter periods, our results show that the phase velocity distributions are well correlated with the large structural crustal domains. The use of local temporary broadband stations in the central part of the studied area gives us the opportunity to observe surface waves showing well-dispersed trains, allowing extended velocity measurements down to 8 s although aliasing due to multipaths become important. The continental regions (Eastern Australia, New Guinea, Fiji islands and New Zealand) show low velocities which are likely due to thick continental crust, whereas the Tasmanian, D'Entrecasteaux, and the Northern and Southern Fiji basins are characterized by higher velocities suggesting thinner oceanic crust. Additional analysis including the anisotropic case and S-wave velocity inversion with depth is in progress. 相似文献
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全国水文站网管理信息系统研究 总被引:2,自引:0,他引:2
全国水文站网管理信息系统是应用GIS技术开发的信息管理系统,它为优化水文站网,提高站网管理水平,提供了迅速、全面的信息支持系统建成后,可实现水上网图、文、声、像信息的查询、漫游和图形报表的输出。介绍了系统的设计与研究成果。 相似文献
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选用中国21个地磁基准台站2011年的绝对子夜均值数据,分析D、H、Z分量年变化量空间分布特征。结果显示,各分量年变化量等值线分布比较均匀,其中:D分量年变化量等值线大致沿南北向分布,零经线附近台站年变化量较小;H分量年变化量等值线大致呈U型分布,且中心点位于甘肃省;Z分量年变化量等值线沿纬线方向,随纬度减小而增大。 相似文献