共查询到20条相似文献,搜索用时 31 毫秒
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Maged Marghany Arthur P. Cracknell Mazlan Hashim 《International Journal of Applied Earth Observation and Geoinformation》2009
This paper introduces a modified formula for the fractal box counting dimension. The method is based on utilization of the probability distribution formula in the fractal box count. The purpose of this method is to use it for the discrimination of oil spill areas from the surrounding features, e.g., sea surface and look-alikes in RADARSAT-1 SAR Wide beam mode (W1) and Standard beam mode (S2) data have been collected under different wind speeds. The results show that the new formula of the fractal box counting dimension is able to discriminate between oil spills, look-alike areas and pixels of the size of a single ship. The W1 mode data illustrate an error standard deviation of 0.05, thus performing a better discrimination of oil spills as compared to S2 mode data. We conclude that automatic detection and discrimination of oil spill and other sea surface features can be opertionalized by using the new formula for fractal box counting. 相似文献
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海洋重力似大地水准面与区域测高似大地水准面的拟合问题 总被引:3,自引:0,他引:3
研究了将陆地重力似大地水准面与GPS水;住似大地水准面拟合的处理方法推广到海洋的问题.首先从理论上证明了当存在海面地形.则海洋大地水准面与似大地水准面不重合.导出了在海洋上大地水;住面差距与高程异常之间差值的公式.由此给出了求定平均海面相对于区域高程基准的正常高以及测高似大地水准面的计算公式。由于测高平均海面与GPS大地高有相近的精度.提出了将海洋重力似大地水准面与区域测高似大地水准面拟合的处理方法.并利用当前最新的海面地形模型和测高平均海面模型做了数值估计。 相似文献
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Polarizaton characteristics of completely diffuse light reflected from a wind roughened sea surface and its total reflectance are studied for various wind speeds on the assumption that distribution of wave slopes around their mean is Gaussian. The angular distribution of diffuse reflectance and polarization status of reflected light are also estimated with a view to exploring possibilities of using these parameters for remote sensing of sea state from a satellite, aircraft or an observation tower. The efficiency of Brewster’s angle technique in eliminating reflected light from the sea surface radiance for remote sensing of subsurface material is examined for non flat sea surface in the light of these results. the results show that the diffuse light reflected from the sea surface contains information on the sea state in the form of its status of polarization and can be used as an observational tool in remote sensing of sea state. The scope and limitations of the method proposed are discussed. 相似文献
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为提高对渤海海冰旋转和平移运动的监测精度,提出一种基于投影变换的相位相关跟踪方法。选取连续8景静止水色成像仪(GOCI)图像序列,根据特征图像窗口的投影变换构造辅助函数,通过寻求函数最优解得到旋转角度集合,选择修正相关系数确定最佳旋转角度,同时根据相位信息实现海冰样本间亚像素级别的平移跟踪,消除传统相位相关法中因忽略图像相频特性所造成的匹配误差。实验结果表明,以手动测量的旋转角度为基准,该方法和传统相位相关法的旋转监测均方根误差的最大值/平均值分别为0.59/0.50与1.41/0.94,跟踪速度提高了50.6%;海冰平移运动的速度矢量与辽东湾的现场实测数据及历史资料记录数据基本一致。该方法对渤海海冰旋转和平移运动具有较好的跟踪效果。 相似文献
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The effects of the deviations of sea surface topography from the geoid are estimated for terrestrial geoid computations as
obtained from Stokes' formula. The results are based on an equal-area expansion of Lisitzin's sea surface topography data
in a spherical harmonic series. It is realized that those data affect mainly the harmonics of degree n≤10. Consequently, in
geoids obtained from combination solutions (where low harmonics are dominated by harmonics as obtained from differential orbit
improvement) the sea surface topography effects are relatively small. 相似文献
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分析了海域使用的时态特性,扩展了基态修正时空数据模型,设计了一种适用于海域使用的宗海时空数据组织模式,实现了历史数据的恢复和海域使用实体的历史追踪。 相似文献
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M.C. Naeije K.F. Wakker R. Scharroo B.A.C. Ambrosius 《ISPRS Journal of Photogrammetry and Remote Sensing》1992,47(5-6)
This paper discusses an altimeter data processing technique designed to compute time series of the mesoscale dynamic sea surface and to produce mean sea surfaces and surface variability. The technique has been applied to Geosat data collected over the North and South Atlantic and the South Indian Ocean. The computed mean sea surfaces show a high correlation with ocean bottom topography, whereas the variability is found to be associated with mesoscale ocean currents. High variability levels are spotted near the Gulfstream Extension and the Agulhas Return Current.Detailed examination of the sea surface and related flow field time series made it possible to identify a large number of eddies and to keep track of them in both the nort-west and south-east Atlantic. Additionally, some of the eddy characteristics have been resolved such as translation and swirl velocity. It is found that the eddy motion is affected by ocean bottom slopes. 相似文献
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On the basis of gravity field model (EIGEN_CG01C), together with multi-altimeter data, the improved deflection of the vertical gridded in 2′×2′ in China marginal sea and gridded in 5′×5′ in the global sea was determined by using the weighted method of along-track least squares, and the accuracy is better than 1.2″ in China marginal sea. As for the quality of the deflection of the vertical, it meets the challenge for the gravity field of high resolution and accuracy. It shows that, compared with the shipboard gravimetry in the sea, the accuracy of the gravity anomalies computed with the marine deflection of the vertical by inverse Vening-Meinesz formula is 7.75 m·s?2. 相似文献
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大气加权平均温度的准确获取对高精度的GPS水汽反演至关重要。文中基于线性回归理论,在分析加权平均温度与地面温度间相关性的基础上,采用一元线性拟合的方法,建立大气加权平均温度经验模型。最后,采用香港地区2006-2015年无线电探空资料对经验模型进行验证。实验结果表明,文中模型计算加权平均温度的整体均方根误差为2.356 K,较Bevis模型精度提高了41.94%,且季节变化对加权平均温度计算的影响并不明显;对于GPS水汽反演,采用本文经验模型反演水汽的均方根误差为1.807 mm,平均偏差为1.362 mm,能够满足GPS可降水量反演的精度,且优于Bevis模型。 相似文献
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The classical integral formula for determining the indirect effect in connection with the Stokes–Helmert method is related
to a planar approximation of the sea level. A strict integral formula, as well as some approximations to it, are derived.
It is concluded that the cap- size truncated integral formulas will suffer from the omission of some long-wavelength contributions,
of the order of 50 cm in high mountains for the classical formula. This long-wavelength information can be represented by
a set of spherical harmonic coefficients of the topography to, say, degree and order 360. Hence, for practical use, a combination
of the classical formula and a set of spherical harmonics is recommended.
Received: 10 March 1998 / Accepted: 16 November 1998 相似文献
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钱文倩 《测绘与空间地理信息》2017,(2):146-148
利用全球平均海平面的高程数据,研究基于反距离权重内插方法来处理Jason测高数据资料得出全球平均海面的数学模型,并将所得结果与利用WHU2013 MSS模型得出的结果进行了对比。此外,还通过计算全球海平面的变化值,分析了全球海平面变化的季节性特征、长期性趋势以及年际变化与厄尔尼诺事件的相关性。 相似文献
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中国东海叶绿素浓度变化分析及其海水温度响应 总被引:1,自引:0,他引:1
海洋叶绿素浓度时空格局分析及与海水温度的响应研究对于海洋资源的开发和保护及赤潮的预防具有重要意义。本文基于2004—2018年东海叶绿素浓度和海水温度数据运用趋势分析及ArcGIS10.2软件,对东海叶绿素浓度作了时空分析研究,并结合海水温度进行了回归分析,以探究叶绿素对海水温度变化的响应机制。结果表明:①东海叶绿素浓度在2004—2018年间没有明显的年际变化特征。年内则随时间上下波动,冬季为波峰,夏季为波谷。离海岸带越近,叶绿素浓度越高。②东海海域海水温度在年际尺度上呈波动式起伏变化。在季节尺度上夏秋两季温度较高,春季次之,冬季最低。从沿海到外海海域海温逐渐升高。③就空间相关性而言,东海海域叶绿素浓度与海水温度整体呈负相关,在不同海域相关程度不同。长江口和外海区域叶绿素浓度与海水温度具有很强的相关性;在沿海区域,由于受到城市环境、经济发展及人类生产生活的影响,海水温度与叶绿素浓度的相关性不明显。 相似文献
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物质世界的不同层次中的事物都具有随时间演化的特性。制图区域内事物的演化使制图区域在不同时刻有不同的状态。在t>t0时,依据制图物体从属于制图区域不同状态的条件,可定义现势地物、消亡地物和新生地物。根据拓朴映射原理,给出了地图符号的一般式,再根据制图对象的时态特征,定义了现势地图符号和失真地图符号。利用同一图上现势地图符号集和失真地图符号集互为补集的关系,提出了地图现势值公式,从而实现了地图现势性概念的定量刻划。由于本公式仅涉及失真符号的面积量算并对经验事实具有解释功能,因而有广阔的应用前景。 相似文献
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利用TOPEX/Poseidon卫星测高资料监测全球海平面变化 总被引:17,自引:1,他引:17
本文利用1993年1月至1999年5月的TOPEX/Poseidon卫星测高数据计算了全球海平变化。海平面模型误差和不恰当的加权方法都会影响全球海平面序列的周年变化,潮汐模型误差对于季节性变化有明显的影响。利用两个高度计算的海平面变化存在周年变化存在明显的差异,利用TOPEX高度计和Poseidon高度计得到的该时段全球平均海平面的变化率分别为2.0mm/a和-0.5mm/a。与南方涛动指数的比较 相似文献
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针对星载接收平台提出了一种利用全球导航卫星系统反射信号(Global Navigation Satellite Systemreflectometry,GNSS-R)进行海冰边界探测的方法。该方法利用导航卫星信号经海冰和海水表面散射后反射信号时延相关功率映射(delay map,DM)的差异,结合镜面反射点位置来探测海冰边界。利用自适应阈值调整算法处理TDS-1卫星数据,获取有效的DM数据,进而得到DM衍生量随镜面反射点位置的变化趋势,并设置DM衍生量的阈值来识别海冰。与全球海冰分布图对比发现,DM衍生量阈值对应的镜面反射点位置与海冰分布图的海冰边界位置基本吻合,证明了DM的有效区时延距离、相关功率的峰值和归一化标准差均可用于海冰边界探测,星载GNSS-R技术在海冰边界探测领域具有较大潜力。 相似文献