资源三号卫星全色影像的姿态角常差检测

根据资源三号卫星传感器的成像原理,构建严格几何模型进行直接定位。通过对不同时间的资源三号全色影像进行实验,验证了姿态角常差的存在,并建立校正模型对其进行改正。利用少量控制点改正姿态角常差后,影像立体定位精度可显著提高。不同地区的实验结果表明,姿态角常差不是恒定不变的,需要根据长期观测建立其变化模型。     

短边三维网的布设及精度

本文讨论了各类短边三维网的布设原理、条件数计算和不确定性考虑,推导了精度估计公式,通过分析得出了几点结论,供布设时参考。     

Seafloor classification of the mound and channel provinces of the Porcupine Seabight: an application of the multibeam angular backscatter data

In this study multibeam angular backscatter data acquired in the eastern slope of the Porcupine Seabight are analysed. Processing of the angular backscatter data using the ‘NRGCOR’ software was made for 29 locations comprising different geological provinces like: carbonate mounds, buried mounds, seafloor channels, and inter-channel areas. A detailed methodology is developed to produce a map of angle-invariant (normalized) backscatter data by correcting the local angular backscatter values. The present paper involves detailed processing steps and related technical aspects of the normalization approach. The presented angle-invariant backscatter map possesses 12 dB dynamic range in terms of grey scale. A clear distinction is seen between the mound dominated northern area (Belgica province) and the Gollum channel seafloor at the southern end of the site. Qualitative analyses of the calculated mean backscatter values i.e., grey scale levels, utilizing angle-invariant backscatter data generally indicate backscatter values are highest (lighter grey scale) in the mound areas followed by buried mounds. The backscatter values are lowest in the inter-channel areas (lowest grey scale level). Moderate backscatter values (medium grey level) are observed from the Gollum and Kings channel data, and significant variability within the channel seafloor provinces. The segmentation of the channel seafloor provinces are made based on the computed grey scale levels for further analyses based on the angular backscatter strength. Three major parameters are utilized to classify four different seafloor provinces of the Porcupine Seabight by employing a semi-empirical method to analyse multibeam angular backscatter data. The predicted backscatter response which has been computed at 20° is the highest for the mound areas. The coefficient of variation (CV) of the mean backscatter response is also the highest for the mound areas. Interestingly, the slope value of the buried mound areas are found to be the highest. However, the channel seafloor of moderate backscatter response presents the lowest slope and CV values. A critical examination of the inter-channel areas indicates less variability within the estimated three parameters. Financial support of this study was granted by the European Commission Fifth Framework Project GEOMOUND (contract no. EVK3-CT-1999-00016).     

Sorted bedforms off Western Long Island,New York,USA: Asymmetrical morphology and twelve‐year migration record

Sorted bedforms are widely present in sediment‐starved littoral and inner shelf settings; they are indicators for hydrodynamic conditions and a primary contributor for the subsurface structure. This study investigated the morphology and migration of sorted bedforms on the inner shelf of Long Beach Barrier Island, New York, USA , by repeat geophysical and geological surveys in 2001, 2005 and 2013 (following superstorm Sandy) involving swath bathymetry, backscatter, chirp seismic reflection data and grab sampling. Swath data revealed that the western sector, comprising the western 75% of the survey region, is dominated by NNE –SSW ‐oriented, 0·5 to 1·0 km wide sorted bedforms with highly asymmetrical cross‐sections, with steeper slopes and coarser sands on the eastern (stoss) flanks. Many secondary bedforms were also observed (north–south to north‐east/south‐west oriented lineation structures) at the western edges of coarse sand zones. The eastern sector displays an unusual sorted bedform pattern that is dominated by coarse‐grained substrate, with isolated patches of fine‐grained sands oriented north‐east/south‐west which are 0·15 to 1·0 km in length and ca 30 to 200 m in width, similar in scale and orientation to the secondary bedforms in the western sector. Comparison analysis of the swath data sets indicates that the primary transverse sorted bedform morphology within the western sector was largely stable over this time frame, although the swales were deepened following the storms. The coarse/fine sand boundaries did migrate, however, moving ca 1 to 5 m eastward between 2001 and 2005, and ca 5 to 20 m westward between 2005 and 2013; the higher migration rates (up to 2·5 m year⁻¹) in the latter time period may be attributable to large storm forcing (for example, hurricanes Irene and Sandy). Significant north‐westward migration of the secondary bedforms and coarse sand patches in the western sector, as well as fine sand patches in the eastern sector were also observed; these features are far more mobile than the primary sorted bedforms, possibly because they are fine sand drifts that do not erode into the coarse substrate. Seismic reflection data revealed a transgressive ravinement beneath sorted bedforms, merging with the sea floor at the bottom of swales. The authors hypothesize that long‐term topographic migration of transverse sorted bedforms contributes to the formation and evolution of the ravinement.     

西准噶尔南部玛依勒洋盆开启、闭合时限:来自中泥盆统与下伏地质体之间角度不整合关系的证据

新疆西准噶尔南部地区出露多条蛇绿岩,其中玛依勒蛇绿岩是该地区比较重要的蛇绿岩之一,其所代表的古洋盆的开启、闭合时限一直是地学界争论的焦点。详细的野外调查发现:玛依勒蛇绿混杂岩呈构造岩块的形式就位于中-上志留统玛依拉山岩群复理石基质中或与寒武纪杂岩体在空间上密切共生,表明玛依勒蛇绿岩所代表的古洋盆至少在寒武纪时期就已经开启,一直持续到中-晚志留世;中泥盆统库鲁木迪组分别角度不整合于中-上志留统玛依拉山岩群和寒武纪杂岩体之上,从而限定了玛依勒洋盆闭合时限的上限为中泥盆世之前。地层剖面分析发现库鲁木迪组与玛依拉山岩群之间在岩性特征、地层序列、沉积环境等方面均存在显著差异,表明晚古生代早期是西准噶尔地区构造演化发展的重要转换时期,库鲁木迪组下部的陆相沉积序列是对玛依勒早古生代洋盆闭合过程的沉积学响应。这将对进一步研究西准噶尔的构造演化和古生代中亚地区的构造格局提供了重要的制约。     

A novel technique for detection of the toxic dinoflagellate, Karenia brevis, in the Gulf of Mexico from remotely sensed ocean color data

Karenia brevis, a toxic dinoflagellate that blooms regularly in the Gulf of Mexico, frequently causes widespread ecological and economic damage and can pose a serious threat to human health. A means for detecting blooms early and monitoring existing blooms that offers high spatial and temporal resolution is desired. Between 1999 and 2001, a large bio-optical data set consisting of spectral measurements of remote-sensing reflectance (R_rs(λ)), absorption (a(λ)), and backscattering (b_b(λ)) along with chlorophyll a concentrations and K. brevis cell counts was collected on the central west Florida shelf (WFS) as part of the Ecology and Oceanography of Harmful Algal Blooms (ECOHAB) and Hyperspectral Coastal Ocean Dynamics Experiment (HyCODE) programs. Reflectance model simulations indicate that absorption due to cellular pigmentation is not responsible for the factor of ∼3–4 decrease observed in R_rs(λ) for waters containing greater than 10⁴ cells l⁻¹ of K. brevis. Instead, particulate backscattering is responsible for this decreased reflectivity. Measured particulate backscattering coefficients were significantly lower when K. brevis concentrations exceeded 10⁴ cells l⁻¹ compared to values measured in high-chlorophyll (>1.5 mg m⁻³), diatom-dominated waters containing fewer than 10⁴ cells l⁻¹ of K. brevis. A classification technique for detecting high-chlorophyll, low-backscattering K. brevis blooms is developed. In addition, a method for quantifying chlorophyll concentrations in positively flagged pixels using fluorescence line height (FLH) data obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS) is introduced. Both techniques are successfully applied to Sea-viewing Wide Field-of-view Sensor (SeaWiFS) and MODIS data acquired in late August 2001 and validated using in situ K. brevis cell concentrations.     

Morphology of pockmarks along the western continental margin of India: Employing multibeam bathymetry and backscatter data

This study addresses the morphology of pockmarks along the western continental margin of India using multibeam bathymetry and backscatter data. Here, for the first time we have utilized the application of ArcGIS (Geographical Information System) for understanding the morphology of pockmarks from the western continental margin of India. The pockmarks observed in water depths of 145–330 m are circular, elliptical or elongated in plan-view, with an average length and width of 157 (±72) m and 83 (±19) m respectively. The average pockmark relief and perimeter are 1.9 (±0.9) m and 412 (±181) m, respectively. The pockmarks have average areas and volumes of 10 759 m² and 15 315 m³ respectively. Spatial separation that coincides with 210 m isobath divides the pockmarks into two groups with differing distributions and morphologies. These pockmarks originated from seepages of biogenic or thermogenic gas or from pore fluids from deeper sources, migrated vertically along the faults. Besides a possible structural control, the pockmark morphologies are also affected by bottom currents and/or by submarine slumping. The average acoustic backscatter strength from pockmark centre is higher (−35 dB) than the average backscatter of the total area (−40 dB), which suggests their possible linkage to the precipitation of diagenitic minerals from biodegradation of seepage material.     

菲律宾海板块西缘强震活动与地球自转角加速度变化关系研究

统计分析了1962~2016年菲律宾海板块与欧亚板块挤压带俯冲带强地震活动与地球自转角加速度变化间的关系。结果显示,研究时段菲律宾海板块西边缘带的25次强地震活动(MS≥7.5)有21次都发生在地球自转角加速度上升期,表明该地区强地震活动与地球自转角加速度之间存在相关性,最后讨论了这种相关性可能的力学机理。     

地物的二向性反射和方向谱特征

本文简要介绍了地物二向性反射的概念及其与地物三维空间结构之间的关系。本文建议在建立高分辨率地物波谱数据库的同时,开展不同类型地物BRDF模型的研究。否则耗资巨大的数据库仍不能有效地应用于结构千变万化的环境遥感。     

全站仪在数字化测图中的误差分析

论述了全站仪在数字化测图中的综合误差以及对测量成果的影响大小,并对其作了详细的探讨和分析。