海洋测高卫星的激光定轨

综述了海洋测高卫星激光定轨的发展近况,论述了我国将发射的HY-2海洋二号卫星实现激光定轨的技术途径及其达到厘米级精度定轨的可能性。     

改进单组CEI基线对卫星定轨精度的影响研究

短基线相位干涉测量是一种被动测角卫星定轨跟踪方法,测量精度高。利用该方法采用单组正交双基线对静地卫星的定轨精度进行了仿真计算,并分别采用物理延长东西基线和东西基线阵列两种方法来考察对卫星定轨精度的改进情况。仿真结果表明,物理延长东西基线可以显著提高定轨精度;若星下点与跟踪网相距较远,则东西向基线阵列可显著提高定轨精度,且该方法对我国北斗卫星群的整体定轨效果很好,能进行几十米级的定轨。     

青岛市城区演化及发展的卫星遥感分析

通过对1988、1997和2002年3个时相的Landsat卫星遥感数据分析，获得适合青岛市城区发展研究的遥感波段组合，获得了青岛近20多年来城区扩展的总体信息。从3个时相遥感影像的对比结果可以看出，1988年到1997年期间青岛市城区扩展较为显著，市南、市北、四方、李沧和崂山5区面积从89．5km^2发展到169．5km^2，1997年以后仅崂山区西部有小面积扩展。城阳和黄岛区的变化较大，1988年到1997年间分别以大约14倍和15倍的速度增长，1997年到2002年城阳城区面积从38．1km^2扩展到50．3km^2，黄岛城区面积翻番。从自然条件的角度来看，青岛市东部多山地发展空间小，城阳区大部分处于海拔100m以下，而城区面积不到总面积的1／6，黄岛区也存在近3倍于现今的城区面积的发展空间。可以看出在环胶州湾的发展带上，城区扩展存在着明显的不平衡现象，今后我们应该改善导致这种不平衡发展的因素，加强胶州湾沿岸交通网的建设，将下一步的发展重点放在胶州湾北岸、西南岸以及崂山东北部低地区域的建设上。     

High-resolution mean sea surface computed with altimeter data of Ers-1 (geodetic mission) and topex-poseidon

The remote-sensing satellite ERS-1, launched in 1991 to study the Earth's environment, was placed on a geodetic (168-day repeat) orbit between 1994 April and 1995 March to map, through altimetric measurements, the gravity field over the whole oceanic domain with a resolution of 8 km at the equator in both along-track and cross-track directions. We have analysed the precise altimeter data of the geodetic mission, and, by also using one year of Topex-Poseidon altimeter data, we have computed a global high-resolution mean sea surface. The various steps involved in pre-processing the ERS-1 data consisted of correcting the data for environmental factors, editing, and reducing, through crossover analyses, the radial orbit error, which directly affects sea-surface height measurements. For this purpose, we adjusted sinusoids at 1 and 2 cycle rev⁻¹ along the ERS-1 profiles in order to minimize crossover differences between ERS-1 and yearly averaged Topex-Poseidon profiles. In effect, the orbit of Topex-Poseidon is very accurately determined (within 2–3 cm for the radial component), so Topex-Poseidon altimeter profiles can serve as a reference to reduce the ERS-1 radial orbit error. The ERS-1 residual orbit error was further reduced through a second crossover analysis between all ascending and descending profiles of the geodetic mission. The along-track ERS-1 and Topex-Poseidon data were then interpolated over the whole oceanic domain on a regular grid of 1/16°× 1/16° size. The mapping of the gridded sea-surface heights reveals the very fine structure of the marine geoid, up until now unknown at a global scale. This new data set will be most useful for marine geophysical and tectonic investigations.     

Mapping of the Culann-Tohil region of Io from Galileo imaging data

We have used Galileo spacecraft data to produce a geomorphologic map of the Culann-Tohil region of Io's antijovian hemisphere. This region includes a newly discovered shield volcano, Ts?i Goab Tholus and a neighboring bright flow field, Ts?i Goab Fluctus, the active Culann Patera and the enigmatic Tohil Mons-Radegast Patera-Tohil Patera complex. Analysis of Voyager global color and Galileo Solid-State Imaging (SSI) high-resolution, regional (50-330 m/pixel), and global color (1.4 km/pixel) images, along with available Galileo Near-Infrared Mapping Spectrometer (NIMS) data, suggests that 16 distinct geologic units can be defined and characterized in this region, including 5 types of diffuse deposits. Ts?i Goab Fluctus is the center of a low-temperature hotspot detected by NIMS late during the Galileo mission, and could represent the best case for active effusive sulfur volcanism detected by Galileo. The Culann volcanic center has produced a range of explosive and effusive deposits, including an outer yellowish ring of enhanced sulfur dioxide (SO₂), an inner red ring of SO₂ with short-chain sulfur (S₃-S₄) contaminants, and two irregular green diffuse deposits (one in Tohil Patera) apparently produced by the interaction of dark, silicate lava flows with sulfurous contaminants ballistically-emplaced from Culann's eruption plume(s). Fresh and red-mantled dark lava flows west of the Culann vent can be contrasted with unusual red-brown flows east of the vent. These red-brown flows have a distinct color that is suggestive of a compositional difference, although whether this is due to surface alteration or distinct lava compositions cannot be determined. The main massif of Tohil Mons is covered with ridges and grooves, defining a unit of tectonically disrupted crustal materials. Tohil Mons also contains a younger unit of mottled crustal materials that were displaced by mass wasting processes. Neighboring Radegast Patera contains a NIMS hotspot and a young lava lake of dark silicate flows, whereas the southwest portion of Tohil Patera contains white flow-like units, perhaps consisting of ‘ponds’ of effusively emplaced SO₂. From 0°-15° S the hummocky bright plains unit away from volcanic centers contains scarps, grooves, pits, graben, and channel-like features, some of which have been modified by erosion. Although the most active volcanic centers appear to be found in structural lows (as indicated by mapping of scarps), DEMs derived from stereo images show that, with the exception of Tohil Mons, there is less than 1 km of relief in the Culann-Tohil region. There is no discernable correlation between centers of active volcanism and topography.     

The Southern Annular Mode and opposite-phased Basin Mode of the Southern Ocean circulation

Over the Southern Ocean the dominant modes of the atmospheric field are known as the Southern Annular Mode (SAM) or Antarctic Oscillation, and the Pacific South American (PSA) pattern. Statistical analysis of sea surface wind (SSW) from satellite observation revealed two leading modes of SAM-like and PSA patterns. In the high latitudes, the SAM-like pattern of the SSW had a large amplitude over the Bellingshausen Basin and Australian-Antarctic Basin, with opposite phase between the two basins. On the intraseasonal time scale, large-scale sea surface height (SSH) also had notable variability, showing a basin-scale anti-phase mode over the two basins. To explain the response of oceanic variations to these atmospheric modes, we analyzed the relationship between the dominant modes of wind stress and large-scale SSH on the intraseasonal time scale. The SAM-like pattern of wind stress was correlated with the SSH variation over the two basins. The SSH basin mode was most simply explained by a simple barotropic response to the SAM-like mode of wind stress, with the curl of opposite phase between the two basins. We conclude that the zonal asymmetry of the wind field of the SAM plays an important role in driving the antiphase SSH basin modes.     

基于GF-4卫星的杭州湾悬浮泥沙浓度遥感监测研究

悬浮泥沙作为重要水质参数,其分布和动态变化对河口及近岸的生态、环境、物质循环等都具有深远的影响。我国静止轨道高分四号(GF-4)卫星数据具有高时间和高空间分辨率的观测优势,在水色遥感上具有重大应用潜力。为探究GF-4卫星对悬浮泥沙浓度的监测能力,本文以杭州湾为研究区,构建反演模型,利用静止海洋水色成像仪进行交叉验证。结果表明,以GF-4卫星第5和第4波段遥感反射率的比值作为遥感因子建立的反演模型精度较高,决定系数为0.92,均方根误差为223.2 mg/L,平均相对误差为17.2%。交叉验证结果显示,GF-4卫星作为一种新的遥感数据源,在低浓度区与静止海洋水色成像仪反演悬浮泥沙浓度分布相似,但在高浓度区的差异随浓度增高而增大,总体可满足中国大部分海区的监测需求。     

HJ卫星图像水稻种植面积的识别分析

 HJ-1A/1B卫星具有较高时空分辨率,是提取水稻等农作物种植面积的潜力数据源。本文以江汉平原腹地的监利县及周边相邻区域为研究区,根据水稻物候历,选取样区水稻生长关键期的多时相HJ-1A/1B卫星数据,利用水稻移栽期的水分信息和生长期的归一化植被指数(NDVI)变化信息,结合陆表水系数(LSWI)、短波红外波段的反射率(R_IRS-B2)、差归一化植被指数(DNDVI),构建了HJ卫星数据的水稻种植面积识别方法,提取了研究区2009-2011年水稻种植面积,得到面积精度和样本点精度均不小于90%,Kappa值不小于0.80的结果。     

黑河调水对下游生态环境恢复效果的卫星遥感监测分析

利用2002年7月至2003年9月EOS/MODIS资料, 计算了黑河尾闾湖——东居延海重新出现后水域面积并分析其变化特征; 通过对2002和2003年6~8月黑河下游额济纳旗和古日乃绿洲植被指数的对比分析, 了解黑河调水对下游植被恢复的效果。结果表明: 东居延海重新出现后仍为季节性湖泊, 其面积2002年初冬最大, 2003年春季迅速减小并于6月6日干涸。随着中游地区再次向下游调水, 2003年8月中旬东居延海再次出现, 干涸时间为70d, 较前些年大大缩短。东居延海再现后对位于河道周围的额济纳旗绿洲植被恢复效果比较明显, 对远离河道的古日乃绿洲植被生长影响不显著。     

遥感图像震害特征组合增强模型及其算法实现

在高分辨率遥感图像中, 不同震害损毁程度的建筑物呈现不同的图像特征, 鉴于此本文提出一种利用遥感图像多特征分析建筑物损毁程度的检测方法. 以2015年尼泊尔M_S8.1地震为例, 结合震后高分一号卫星全色遥感图像和城市道路矢量数据提供的街区信息, 以建筑物街区为单元进行图像纹理提取和局部空间统计等多类别图像特征参数分析, 并构建多特征分类模型, 将震后建筑物街区划分为基本完好、 部分损毁和严重损毁等3个类别. 试验结果表明, 本文提取的参数能够有效地表征损毁建筑物的图像特征, 而且建筑物震害损毁检测精度较高. 该方法可用于建筑物震害损毁信息的快速提取, 为震后应急救援提供指导; 同时还可为我国自主研发高分卫星遥感数据在地震灾害信息提取中的应用提供技术参考与方法借鉴.