一种陆地卫星影像厚云阴影检测方法     

卢鑫  赵红莉  杨树文  冶运涛  杨兴旺 《测绘科学》2016,41(5):87-90

针对现有的遥感影像厚云阴影监测方法存在过程复杂、精度不高等问题,该文提出一种TM影像厚云阴影检测方法:通过阈值分割提取影像中的所有阴影;对比一幅近时相的无云影像,分离出厚云的阴影,即云阴影为"有云"影像比"无云"影像多出的阴影;最后将提取结果与人机交互、云阴影增强模型法提取的结果进行对比分析。实验结果表明该方法提取精度较高,可以快速、准确地提取TM影像中的厚云阴影。  相似文献   

地质灾害监测预警信息共享机制研究   总被引：1，自引：0，他引：1  

黄露  谢忠  罗显刚 《测绘科学》2016,(5):55-59

为了提高共同防御地质灾害能力、建立多部门地质灾害监测预警信息的共享机制,该文运用云计算技术设计了一种面向服务的"终端-云端-虚拟端"架构模式,由国土资源、气象、水利等部门共同参与的地质灾害监测预警信息共享总体设计框架,并探讨了气象水利雨量数据对接标准建设、数据服务接口建设、地质灾害数据中心建设以及功能服务建设,为终端应用系统和用户提供一系列标准化的功能服务。最后通过原型系统验证,结果证明了提出方法的可行性。  相似文献   

车载LiDAR点云相连行道树精细分割   总被引：1，自引：0，他引：1  

张西童  李永强  毛杰  李有鹏  黄腾达 《测绘科学》2016,41(8):111-115

针对车载激光雷达获取的行道树树冠点云相连问题,该文提出了基于树木生长模型的距离加权分割方法。首先通过等距原则将相连树粗分割为单株树木,采用求差和拟合算法获得树木高度、胸径等属性信息;再根据树木的理论和实际生长模型,计算得到树冠距离加权值;最后在此基础上对树冠进行迭代处理,实现邻接行道树点云的精确分割。经过不同树种试验验证,该算法能够实现对多棵相连树点云的进一步精确分割。  相似文献   

非常复杂的异常台风路径的卫星云图特征   总被引：1，自引：0，他引：1  

朱奇志  包澄澜 《海洋预报》2001,18(2):54-61

异常的台风是台风预报中的一个主要难点，而非常复杂的怪路径虽然次数很吵，但却无法预报，有些甚至在事后都难以解释，本文对9119号台风（Nat)的一次怪路径作了个例分析，指出卫星云图不仅能对9119怪路径作出很好的解释，而且在其二次热带风暴一台风强度阶段能作出较好的预报。  相似文献   

A new hypothesis about the surface circulation in the eastern basin of the mediterranean sea   总被引：3，自引：1，他引：3  

Najwa Hamad  Claude Millot  Isabelle Taupier-Letage 《Progress in Oceanography》2005,66(2-4):287

In time, the circulation of the Atlantic Water (AW) in the eastern basin of the Mediterranean Sea has been described differently, according to two major representations. The historical one, which began with the scheme from Nielsen in 1912 and has been refined up to the 1980s, favours a counterclockwise circulation in the whole basin, with AW flowing in its southern part as a broad flow off Libya and Egypt (from the Ionian to the Levantine subbasins), then continuing along Middle-East and Turkey before flowing back westwards. The more recent one, issued in the 1990s, favours a clockwise circulation in the northern part of the Ionian continuing offshore across the basin from the Cretan to the central part of the Levantine as the so-called “Mid-Mediterranean Jet”. This jet is depicted then as splitting both clockwise in the southeastern part of the basin and counterclockwise off Turkey (where this representation agrees with the former). Because the recent representation cannot be considered as a refinement of the historical ones, we have been interested in understanding why a given data set available to everybody is interpreted in such different ways.In the Algerian subbasin, the combined use of satellite infrared images and a significant amount of in situ data sets (hydrology and both Eulerian and Lagrangian current measurements) allowed us to solve a similar controversy. Therefore, we examined the circulation features in the eastern basin, undertaking the detailed analysis of 1000 daily and weekly composite images spanning the period 1996–2000, and of monthly composite images available since 1985. Whenever in situ observations were available, we have confronted them with the satellite thermal signatures and have shown that both are consistent. This paper focuses on the overall (basin scale) results while the detailed ones are published in an other paper. The new scheme we propose is basically a refined version of the historical ones: the circulation of AW is counterclockwise in the whole eastern basin but it is more constrained alongslope than previously thought, and the broadening historically schematised appears to be due to intense mesoscale eddies mainly generated by the instability of this circulation.  相似文献   

The Increase of Biogenic Sulfate Aerosol and Particle Number in Marine Atmosphere over the Northwestern North Pacific     

Atsushi Ooki  Kazuhiko Miura  Mitsuo Uematsu 《Journal of Oceanography》2003,59(6):799-807

During a cruise aboard the R/V Hakuho-maru in the northwestern North Pacific in the summer of 1998 the particle number concentrations and the major ionic components of size fractionated aerosols were measured to investigate the aerosol produced by marine biological activity. Continuous low concentrations of nitrate (<1.8 nmol m⁻³), similar to the marine air background level, were found over the northwestern North Pacific (40–45°N) and the Sea of Okhotsk (44–45°N). Over the Sea of Okhotsk, a high concentration of chlorophyll-a (5.4 mg m⁻³) in seawater was observed, and atmospheric concentrations of non sea-salt (nss-) sulfate (44 nmol m⁻³), methane sulfonic acid (MSA) (1.8 nmol m⁻³) and particle number in the size range of 0.1 < D < 0.5 μm (199 cm⁻³) were found to be 9, 7, and 2 times, respectively, higher than those in the background marine air. The increase in particle number concentrations mainly in the size range of 0.2 < D < 0.3 μm was likely caused by the increase of biogenic sulfate over the high productive region of the Sea of Okhotsk. In humid air conditions (R.H. > 96%), the increased biogenic sulfate that condensed the large amount of water vapor would not have sufficient solute mass to activate as cloud condensation nuclei (CNN) and would remain as aerosol particles in the marine air with frequent sea-fogs over the high productive region. Biogenic sulfate originating from dimethyl sulfide (DMS) would gradually grow into the CCN size and continuously supply a great number of CCN to the marine air in the northwestern North Pacific. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

表面波破碎泡径谱的理论研究     

韩磊  袁业立 《海洋科学进展》2007,25(3):289-294

采用新的无量纲变量组合推导出波浪破碎形成的气泡总数与气体体积卷入率、湍流能谱密度以及表面张力之间的关系;利用观测结果提出两点假设,并据此将泡径谱N(a)推广为随泡径和深度的分布函数N(a,z)。  相似文献   

热带三大洋海表温度和云水关系的初探     

刘秦玉  秦婷 《中国海洋大学学报(自然科学版)》2007,37(3):345-350

热带太平洋、大西洋和热带印度洋是全球海洋-大气相互作用最显著的海域。为了探讨热带三大洋局地海洋-大气相互作用中的某些特征,利用新的卫星遥感资料对热带三大洋的云水和海表温度(SST)异常变化进行了统计相关分析。研究发现:在赤道太平洋和赤道大西洋云水和SST二者在超前或滞后5周内都呈现明显的正相关关系,表明3个赤道海域云水和SST之间具有明显的相互作用正反馈机制;在热带西印度洋SST异常超前CLW异常一周时,正相关系数最大,SST的变化导致云水的变化;而在以较冷海水为下垫面的赤道外东北太平洋,东南太平洋以及赤道外的南大西洋海域,二者呈明显的负相关关系,云水的变化会引起SST的变化。位于菲律宾以东的热带西北太平洋区,云水量的变化引起SST的变化;而赤道东印度洋暖池区即存在云水量的增加(减少)引起SST降低(升高)的现象,也存在SST降低(升高)引起云水量的减少(增加)的现象。以上结果将为进一步理解海洋-大气相互作用,在数值模式中正确设计海洋-大气边界层参数化方案提供参考。  相似文献   

Trajectory of Mesoscale Eddies in the Kuroshio Recirculation Region   总被引：4，自引：1，他引：4  

Naoto Ebuchi  Kimio Hanawa 《Journal of Oceanography》2001,57(4):471-480

Trajectories of mesoscale eddies in the Kuroshio recirculation region were investigated by using sea surface height (SSH) anomaly observed by the TOPEX/POSEIDON and ERS altimeters. Cyclonic and anticyclonic eddies have been traced on maps of the filtered SSH anomaly fields composed from the altimeter observations every ten days. Both the cyclonic and anticyclonic eddies propagate westward in the Kuroshio recirculation region from a region south of the Kuroshio Extension. The propagation speed of these eddies has been estimated as about 7 cm s⁻¹, which is much faster than the phase speed theoretically estimated for the baroclinic first-mode Rossby wave in the study area. It was also found that in the Izu-Ogasawara Ridge region, most of eddies pass through the gap between the Hachijojima Island and Ogasawara (Bonin) Islands, and some of the eddies decay around the Izu-Ogasawara Ridge. It seems that the trajectory of the eddies is crucially affected by the bottom topography. In the region south of Shikoku and east of Kyushu, some of the eddies coalesce with the Kuroshio. It is also suggested that this coalescence may trigger the path variation of the Kuroshio in the sea south of Japan. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

Sea surface temperature observation by Global Imager (GLI)/ADEOS-II: Algorithm and accuracy of the product   总被引：1，自引：0，他引：1  

Futoki Sakaida  Kohtaro Hosoda  Masao Moriyama  Hiroshi Murakami  Akira Mukaida  Hiroshi Kawamura 《Journal of Oceanography》2006,62(3):311-319

A sea surface temperature (SST) retrieval algorithm for Global Imager (GLI) aboard the ADEOS-II satellite has been developed. The algorithm is used to produce the standard SST product in the Japan Aerospace Exploration Agency (JAXA). The algorithm for cloud screening is formed by combinations of various types of tests to detect cloud-contaminated pixels. The combination is changed according to the solar zenith angle, which enables us to detect clouds even in the sun glitter region in daytime. The parameters in the cloud-detection tests have been tuned using the GLI global observations. SST is calculated by the Multi-Channel SST (MCSST) technique from the detected clear pixels. Using drifting buoy measurements, match-up data are produced to derive the coefficients of the MCSST equations and to examine their performance. The bias and RMSE of the GLI SST are 0.03 K and 0.66 K for daytime and, −0.01 K and 0.70 K for nighttime, respectively.  相似文献