基于ISCAN和CYCLONE的三维街景数据处理方法     

邢建华  李朝奎  方文  李慧婷 《地理信息世界》2016,(1):124-128

如何快速有效地获取高精度、高分辨率的地理空间信息数据已经成为城市智慧化发展的重要问题,本文分析了三维街景地图的发展现状与目前多数街景数据采集手段存在的问题,介绍了利用中海达一体化移动三维激光测量系统采集点云数据的过程,以及结合徕卡CYCLONE软件进行建模的方法,对原始测量的点云数据进行去噪、平滑、拼接配准等处理后得到目标建筑物精准的表面信息,进而构建三维表面模型,将校正过的照片进行纹理映射得到真实的三维模型。实验证明:此方法可快速地获取较为精准的点云数据并且实现对建筑物的快速建模。  相似文献   

祁连山南麓夏季地形云特征及山谷风影响分析     

刘蓓 《气象科技》2016,44(1):67-75

利用门源、祁连气象站2004—2013年6—8月逐时常规观测资料,分析了地形云的日变化特征,结果表明:两站夏季总、低云量的日变化呈现双峰型特征;层积云和积雨云的日变化呈反相特征。层积云出现频率最高在清晨,积雨云在午后至傍晚出现频率最高;门源站层积云出现频率高于祁连站,而祁连站积雨云出现频率高于门源站。两站山谷风环流特征明显,风速最大值出现在午后,最小值出现在清晨;门源站谷风控制时间长于山风,祁连站山风控制时间长于谷风。两站积雨云出现时间与山谷风风速最大值出现时间之间具有对应关系;有天气系统影响时形成的积雨云,持续时间较长,降水较多;仅由地形风及热力、湍流作用形成的积雨云,持续时间较短,降水较少。层积云的形成有3种类型:第1种由高层云演变而来;第2种由积雨云对流发展受到抑制而形成;第3种由局地山谷风环流形成,云的形成与山谷风环流以及边界层日变化特征相关。  相似文献   

华北地区气溶胶垂直分布特征的观测与分析     

孙强  范学花  夏祥鳌 《气象与环境科学》2016,39(1):26-33

利用2006 2013年CALIOP激光雷达Level 1B数据的气溶胶衰减后向散射系数、退偏比和色比观测,分析了华北地区大气气溶胶光学特性的垂直分布特征。统计结果显示:2010-2013年,华北地区4-8 km高度范围内衰减后向散射系数均值呈减小的趋势,而0-4 km高度范围内衰减后向散射系数均值呈增长趋势。说明2010年以后近地面层(0-2 km)气溶胶散射作用逐渐增强,高层(4-8 km)气溶胶散射作用逐渐降低,这与近年华北地区霾天气(颗粒物主要聚集在近地层)日趋增加、沙尘天气(沙尘气溶胶层经常存在于4-8 km的范围)有所减少相吻合。20062013年,华北地区冬季0-4 km高度范围内衰减后向散射系数均值最大,近地面层气溶胶散射作用最大,这与该地区冬季取暖燃烧排放增加有关。春、秋两季4-8 km高度范围内衰减后向散射系数均值较大,夏季0-8 km各高度范围内衰减后向散射系数均最小,说明春、秋季节的气溶胶散射贡献主要来自4-8 km的对流层上部大气。春季对流层上部的高后向散射系数与华北地区春季频发的沙尘天气有关,秋季对流层上部的高后向散射系数与华北收获季节的生物质燃烧有关。2008年以后,华北地区2-8 km范围内各高度层的退偏比均值逐年减小,这说明规则的球形气溶胶粒子在近几年有所增加。0-4 km范围的低层大气,2009年后色比均值缓慢增加。而6-8 km范围内的色比均值从2008年后一直都是减小的,说明2008年后对流层上部大气(4-8 km)气溶胶粒子的尺度在减小,这也与近几年沙尘天气减少、霾天数增加的现象是一致的。0-8 km各个高度范围内的退偏比和色比均值春季最大,且退偏比随着高度的增加而增加,再次证明春季华北受沙尘天气影响,不规则的粗粒子气溶胶最多。夏、冬季节近地面层(0-2km)退偏比和色比均值略大于2-4 km高度层的,夏、冬两季近地面主要以人为活动排放的气溶胶为主,冬季除了汽车尾气排放和工业排放外,还有取暖增加的排放。近地面层易受人为活动影响混合一些不规则气溶胶。  相似文献   

西北太平洋热带云团发展与两类El Nio事件的联系          下载免费PDF全文

耿焕同  黄超  张伟  史达伟 《大气科学学报》2016,39(2):189-197

利用1982—2009年全球热带云团数据集、NCEP/NCAR再分析资料和英国Hadley中心海温资料,并引入热带云团生成率(Genesis Productivity,GP)来分析EP(Eastern Pacific)El Nio和CP(Central Pacific)El Nio事件与西北太平洋热带云团发展的相关性。研究表明,1)夏秋两季GP与Nio3指数在东南区(SE)均为显著正相关,在西南区(SW)仅秋季呈显著正相关;GP与EMI(El Nio Modoki Index)指数在夏季SE区域为显著正相关,在秋季南中国海(South China Sea,SCS)区呈负相关。2)在EP El Nio年,夏季SE区域的GP增大与低层涡度、高层散度以及低层相对湿度的相对增大一致。夏季SW区域与秋季SE区域的GP增大与有利的高低空配置相关,La Nia年则与之相反。3)在CP El Nio年,夏季SE区域的GP增大伴随着低层涡度和高层散度的增加,同时与充足的水汽及弱风切变相吻合;而秋季SCS区域的GP下降源于正涡度带、正散度带以及水汽带的东移。  相似文献   

Elimination of Interferences in the Determination of Palladium,Platinum and Rhodium Mass Fractions in Moss Samples using ICP‐MS/MS          下载免费PDF全文

Terhi Suoranta  Syed N. H. Bokhari  Thomas Meisel  Matti Niemelä  Paavo Perämäki 《Geostandards and Geoanalytical Research》2016,40(4):559-569

Moss samples (Pleurozium schreberi) exposed to traffic‐related emission of Pd, Pt and Rh were analysed in this study. Successful elimination of interferences was achieved in the determination of Pd, Pt and Rh mass fractions in these samples using inductively coupled plasma‐tandem mass spectrometry (ICP‐MS/MS). Based on the results, a reliable determination of Pd, Pt and Rh mass fractions in microwave‐digested moss samples was obtained using ammonia (10% NH₃ in He) in the collision/reaction cell when ¹⁰³Rh was measured either on‐mass (103→103) or with mass‐shift (103→171) and mass‐shifts for ¹⁰⁸Pd (108→159) and ¹⁹⁵Pt (195→229) were used. The ICP‐MS/MS procedure was validated using BCR‐723 (road dust) as a reference material. In addition, a good agreement between the ICP‐MS/MS results and the results obtained with cloud point extraction and quadrupole ICP‐MS was observed for the moss samples.  相似文献   

南海南部季风的自动气象站观测系统设计          下载免费PDF全文

李超  宁春林  刘宝超  苏清磊 《海岸工程》2016,35(4):42-50

为了更好地认识季风对南海南部海洋环境变化和生态系统变化的影响,在马来西亚的Bachok海洋站设计、安装了一种轻便型、耐腐蚀的海岸带自动气象站系统。该系统自动采集气温、气压、风速和风向、相对湿度、降水、太阳短波辐射和长波辐射共7个气象要素,将数据存入CF卡并通过串口主动上传至上位机,通过服务程序实时显示气象数据并上传气象数据至云服务器供用户下载。本系统利用实验室校准和最小二乘法的修正来保证数据质量,近一年的连续测试表明该系统的性能稳定,在2016-05纳入到全球气象观测区域站中。  相似文献   

Evolution of fluid flow and heat distribution over geological time scales at the margin of unconfined and confined carbonate sequences - A numerical investigation based on the Buda Thermal Karst analogue     

《Marine and Petroleum Geology》2016

Hydrogeological processes acting at the margins of confined and unconfined thick carbonate sequences are particularly interesting due to a complex system evolution including partial uplift of fully confined carbonate systems and subsequent erosion of cover layers. We provide insights into this evolution by simulating coupled density-dependent fluid flow and heat transport based on the Buda Thermal Karst (BTK) system (Hungary) in a 2D vertical plane. Applying an equivalent porous medium (EPM) approach using the Heatflow-Smoker finite element model, scenario modelling of three evolutionary steps was carried out between the fully-confined carbonate stage through to partly and completely unconfined conditions over the western ridge. The numerical simulations were used to derive the main evolutionary characteristics of groundwater flow and heat transport patterns for the unconfined and confined parts of the hydrogeologic system. The initial fully-confined state led to the development of thermal convection cells due to the insulating role of the low-permeability confining layer, which facilitates buoyancy-driven flow by restricting the dissipation of heat. Over geological time, these cells were gradually overprinted by gravity-driven flow and thermal advection due to uplift of the west ridge. The limited thickness of the cover allowed sufficient water infiltration into the system, which led to increased cooling. Further uplifting led to a prevalence of gravity-driven groundwater flow. The results highlight the critical role of confining formations on flow patterns, and their effect on heat distribution and dissipation over geological time scales. The results have important implications for heat accumulation as well as for the development of a deep geothermal energy potential in confined carbonates.  相似文献   

Fitting boxes to Manhattan scenes using linear integer programming   总被引：1，自引：0，他引：1  

Minglei Li  Liangliang Nan  Shaochuang Liu 《International Journal of Digital Earth》2016,9(8):806-817

We propose an approach for automatic generation of building models by assembling a set of boxes using a Manhattan-world assumption. The method first aligns the point cloud with a per-building local coordinate system, and then fits axis-aligned planes to the point cloud through an iterative regularization process. The refined planes partition the space of the data into a series of compact cubic cells (candidate boxes) spanning the entire 3D space of the input data. We then choose to approximate the target building by the assembly of a subset of these candidate boxes using a binary linear programming formulation. The objective function is designed to maximize the point cloud coverage and the compactness of the final model. Finally, all selected boxes are merged into a lightweight polygonal mesh model, which is suitable for interactive visualization of large scale urban scenes. Experimental results and a comparison with state-of-the-art methods demonstrate the effectiveness of the proposed framework.  相似文献   

GRAPES-Meso模式浅对流云辐射效应的改进试验   总被引：1，自引：0，他引：1  

康家琦  王建捷  黄丽萍  万子为 《气象学报》2016,74(5):715-732

在万子为等（2015）对GRAPES-Meso模式浅对流参数化改进的基础上,进一步引入了浅对流云量诊断计算,并设计旨在完善浅对流云辐射效应的浅云云量和云中水凝物的补偿方案,以改进模式低层云量偏少和浅对流云辐射效应不足的问题。通过对数值试验结果的诊断和对比分析以及与观测的比较,重点考察了浅对流云量计算与浅对流激发的协调性、浅对流云对低云补偿后所产生的辐射效应以及对模式地面要素预报的影响等,验证了改进方案的合理性与有效性。结果表明:（1）浅对流云量诊断计算合理,其云覆盖区与浅对流激发区相吻合,引入浅对流云量的计算可减小模式云量的计算偏差、使其向观测结果靠近;（2）改进方案在浅对流发生区低层0.5-4 km高度范围内,对影响模式云辐射过程的浅云云量和云中水凝物形成有效补偿,最明显的浅云补偿在1-1.5 km高度处,浅对流活跃时期浅对流过程对浅云水凝物（云水和雨水之和）的补偿量可达20%-55%;（3）云光学厚度对浅云水凝物的补偿响应合理,即水凝物的补偿引起云光学厚度增大,两者的变化特征在时空分布上十分相似,且云光学厚度之变化受云水补偿的影响比受雨水补偿的影响更明显;（4）在白天时段,浅云补偿所产生的辐射效应使模式地表太阳总辐射有所下降,缩小了与观测的偏差,进而使地表温度和地面2 m气温模拟偏差减小。改进方案在缓解模式云量偏少、地表太阳总辐射偏强和地面2 m气温偏高等方面的作用,在批量试验中得到了验证。   相似文献   

Diagnosis of the forcing of inertial-gravity waves in a severe convection system     

Lingkun Ran  Changsheng Chen 《大气科学进展》2016,33(11):1271-1284

The non-hydrostatic wave equation set in Cartesian coordinates is rearranged to gain insight into wave generation in a mesoscale severe convection system. The wave equation is characterized by a wave operator on the lhs, and forcing involving three terms—linear and nonlinear terms, and diabatic heating—on the rhs. The equation was applied to a case of severe convection that occurred in East China. The calculation with simulation data showed that the diabatic forcing and linear and nonlinear forcing presented large magnitude at different altitudes in the severe convection region. Further analysis revealed the diabatic forcing due to condensational latent heating had an important influence on the generation of gravity waves in the middle and lower levels. The linear forcing resulting from the Laplacian of potential-temperature linear forcing was dominant in the middle and upper levels. The nonlinear forcing was determined by the Laplacian of potential-temperature nonlinear forcing. Therefore, the forcing of gravity waves was closely associated with the thermodynamic processes in the severe convection case. The reason may be that, besides the vertical component of pressure gradient force, the vertical oscillation of atmospheric particles was dominated by the buoyancy for inertial gravity waves. The latent heating and potential-temperature linear and nonlinear forcing played an important role in the buoyancy tendency. Consequently, these thermodynamic elements influenced the evolution of inertial-gravity waves.  相似文献