利用气象卫星资料分析长江口通海航道泥沙分布

利用气象卫星的时间、空间上的优势,在总结长江河口河槽演变基本模式的基础上,结合卫星图像的分析,确定和研究长江口泥沙地区悬移质的输移路线和活动范围,探讨分析了长江口悬浮泥沙浓度分布动态,分析了滩槽泥沙交换对航道淤积的影响,为长江口深水航道整治方案的确定提供了科学依据。     

舟山群岛海岸线遥感信息提取及时空演变分析

作为我国第一个由岛屿组成的地级市,舟山市具备丰富的海洋资源,准确监测海岸线动态信息对其意义重大.而悬浮泥沙含量较大、岸线曲折、滩涂众多等给舟山群岛海岸线提取和时空演变分析带来了挑战.针对此问题,基于缨帽变换在表征地物含水量方面的优势,利用长时间序列卫星遥感数据开展海岸线时空演变分析.结果表明,该方法能够有效去除悬浮泥沙...     

基于MODIS 数据的悬浮泥沙定量遥感方法

以黄海及东海海域为对象,研究用MOD IS数据提取我国海域悬浮泥沙时空分布的定量遥感方法,建立了基于MOD IS数据的悬浮泥沙定量遥感实用模式。研究表明,用250 m和1 000 m分辨率的MOD IS数据进行悬浮泥沙浓度的定量遥感,可以达到实际应用的精度要求。这说明,MOD IS数据是研究近岸水体中悬浮物输运变化规律的一种经济实用数据源。     

基于遥感的鄱阳湖丰水期悬浮泥沙数值模拟预测

悬浮泥沙是湖泊水体的重要水质要素之一,是湖泊水生态系统重要影响因子。利用遥感提取的鄱阳湖底质类型数据,对各类型底质区域上泥沙模型参数进行敏感性分析,基于2011年实测的不同底质区上泥沙浓度数据率定得到空间上不一致的泥沙模型参数,从而建立鄱阳湖丰水期二维悬浮泥沙输运模型。利用该模型模拟预测2013年丰水期悬浮泥沙输移过程,实测泥沙数据验证表明,模拟悬浮泥沙均方根误差为19.8 mg/L,相关系数R2为0.78,该模型能够较好地进行悬浮泥沙模拟预测。对比模型模拟和遥感反演的悬浮泥沙空间分布,两者具有较好的空间一致性,进一步表明该模型能够可靠地模拟预测鄱阳湖悬浮泥沙的时空动态变化。本研究充分利用遥感数据辅助建立鄱阳湖泥沙输移模型,为湖泊水环境动态变化监测提供有力的技术方法支撑,为进一步进行鄱阳湖水环境动态变化的数值模拟预测研究提供基础。     

近岸水体表层悬浮泥沙平均粒径遥感反演

悬浮泥沙的粒径分布特征不仅体现了悬浮颗粒态物质的存在状态,而且可以指示水动力及再悬浮作用的过程和强度,因此研究悬浮泥沙粒径分布特征具有重要意义。利用Mie理论建立悬浮泥沙平均粒径反演模型,结果表明,悬浮泥沙后向散射系数与其平均粒径的三次方线性关系明显,4个波段(412nm、443nm、555nm、667nm)拟合方程决定系数均在0.93以上,拟合误差最小值为16.6322%(412nm),最大值为20.3143%(667nm)。利用QAA算法从MODIS影像上反演研究区域悬浮泥沙后向散射系数,并结合反演的悬浮泥沙浓度推算研究区域表层悬浮泥沙的平均粒径。对比发现,近岸高悬浮泥沙区域的反演结果与实测数据吻合较好,相关研究可以为深入开展陆海相互作用、海洋生态系统演变和海洋参与全球碳循环等研究提供重要数据支持。     

近海岸悬浮泥沙遥感反演模型的分析探讨

简要介绍了国内外近海岸悬浮泥沙定量化遥感反演的研究进展及悬浮泥沙遥感反演模型的建立方法,通过对国内外近年研究的部分悬浮泥沙遥感反演模型进行简单分类、对比分析得出其优缺点,并针对部分悬浮泥沙遥感反演模型的不足和目前遥感技术在悬浮泥沙定量反演中的应用提出了一些肤浅见解。     

杭州湾悬浮泥沙多时相遥感分析

本文根据1984年的NOAA卫星多时相遥感资料,对杭州湾及其周围海区的表层悬浮泥沙浓度分布特征、扩散范围及季节性变化等作了分析与研究。并对悬浮泥沙影响建港工程及海区自然环境净化等问题进行了讨论。     

随机森林回归模型的悬浮泥沙浓度遥感估算

三峡工程蓄水以来,清水下泄,坝下游河段发生了长时间、长距离的沿程冲刷,河流悬浮泥沙浓度发生改变,给沿岸生态系统带来了不利影响。随机森林算法灵活、稳健,已被广泛应用于各类生态环境变量的回归预测分析,但其在水体悬浮泥沙浓度估算方面的能力尚未得到充分认识。基于泥沙站点监测数据和MODIS卫星遥感反射率数据,通过构建随机森林非参数回归预测模型,对三峡工程坝下游宜昌至城陵矶河段在建坝前后14年间(2002年—2015年)各月的悬浮泥沙浓度进行遥感估算。研究表明:(1)基于随机森林的悬浮泥沙浓度估算模型表现较好,模型预测值与实测值间相关性好、预测精度高,优于其他模型(线性回归、支持向量机、人工神经网络模型)。(2)在参与模型构建的MODIS波段变量中,红波段被认为是最重要的预测变量,但不能单独使用它进行预测,悬浮泥沙遥感预测需要多变量共同参与。(3)将悬浮泥沙数据按季节分类所构建的随机森林模型,其平均误差为0.46 mg/L,平均相对均方根误差为12.33%,估算效果最优,能够满足较高精度下悬浮泥沙浓度估算的需求。综上,可以考虑以季节为划分依据,用随机森林回归模型估算悬浮泥沙浓度,并用于后期坝下游河道悬浮泥沙浓度时空反演。     

辐射沙脊群海域悬沙场遥感反演方法

利用2006年江苏908调查水文泥沙测验数据和同期MODIS影像建立遥感定量反演模式,获取了半个潮周期的悬沙场以及全潮平均悬沙场,进行了辐射沙脊群海域悬沙场遥感反演方法的研究,并结合悬沙数学模型对结果进行了验证。研究表明,在辐射沙脊群海域,敏感参数(B1-B4)/(B1+B4)的对数模式反演悬沙场精度较高;遥感反演结果在总体上与数学模型计算结果相似,悬沙高值区主要分布在弶港、废黄河口和长江口附近;在细节上比数学模型表现得更精细,能清晰地反映河口、沙洲、水道等地貌对悬沙分布的影响。     

曹妃甸近海Ⅱ类水体光谱反射率与悬浮泥沙浓度相关性研究

利用水面以上法对曹妃甸近海Ⅱ类水体进行现场光谱测量,对获取的数据与同步采集的水体悬浮泥沙浓度进行相关分析,初步建立了水体悬浮泥沙浓度与TM数据对应的可见光至近红外波段遥感反射率的经验模型.研究结果表明:该地区近海Ⅱ类水体的反射率随悬浮泥沙浓度的增加而增加,在泥沙浓度小于20 mg/L时,570 nm处的反射率随泥沙浓度增加而增大的特征优于670 nm处的,但当泥沙浓度大于20 mg/L时,后者反射率的增幅明显优于前者;TM 3中心波段处的反射率与表层悬浮泥沙浓度(SPM)呈显著的指数相关,利用模型计算的悬浮泥沙浓度平均相对误差低于±28%.     

基于遥感反演结果的悬浮泥沙时空动态规律研究--以珠江河口及邻近海域为例

选择了珠江口及其邻近海域1995年~2000年152个时相的NOAA/AVHRR影像反演的悬浮泥沙浓度结果,通过对悬浮泥沙反演结果影像的叠加,求算叠加像素点像素平均值,计算了研究海域在1995~2000年间月、季及丰枯水期几个时间尺度上的悬浮泥沙平均浓度及其平均变化。结果大致表明了陆地径流对海域的影响范围和悬浮泥沙在海域的运动方向。     

Characterization of spatial and temporal variation of suspended sediments in the Yellow and East China Seas using satellite ocean color data

Total suspended sediment (TSS) data concentrations are retrieved from two sets of satellite ocean color data (the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard Aqua and the Korean Geostationary Ocean Color Imager (GOCI)) using an existing regional model to characterize spatial and temporal variation of TSS in the Yellow and East China Seas. MODIS-derived TSS maps show that TSS concentrations are, in general, high along the Korean and Chinese coasts including the Bohai Sea and the Yangtz River estuary, and lower in the middle of the Yellow Sea and the southeastern area of the East China Sea. The monthly average of 10-year MODIS data reveals that TSS values are highest during winter (January to February) and lowest in summer (July to August). Short-term TSS concentrations retrieved from GOCI data showed the dominant influence of semi-diurnal tidal changes on sediment dynamics through temporal (hourly) and spatial distribution in coastal zones of the Yellow sea. The results presented here demonstrate that the satellite-derived TSS products can be utilized as an application tool for future studies on long- and short-term sediment dynamics of turbid coastal waters. In particular, GOCI observations provide unique important capabilities to characterize and quantify the water properties at high temporal (hourly) and spatial (0.5 km) resolutions in the turbid coastal waters of the Yellow Sea and its vicinities.     

黄河口水体光谱特性及悬沙浓度遥感估测

通过黄河口含沙水体野外遥感光谱反射率的观测实验，探讨了黄河口水体表观光谱特性，分析了悬浮体中有机颗粒含量和悬沙粒度对光谱特性的影响。针对Landsat TM／ETM^＋影像波段特性，对黄河口含沙水体在其可见光至近红外4个波段的光谱特性进行了模拟分析，并结合表观光谱观测数据建立了经验回归函数，以估测不同时相黄河口水体表层悬沙的浓度。     

应用遥感技术分析韩江河口悬沙的动态特征

利用韩江河口近20多a的卫星影像资料，结合GIS技术，通过对韩江河口流势、流态和水沙输移特征的分析，探讨韩江河口 出口水流动力状况及其对泥沙输移的影响。结果表明，韩江河口区内泥沙含量较低，在河口区内涨落潮流呈西南-东北向运动，在 河口外则易受西南沿岸流影响，具有近岸输沙的特性。     

九龙江下游水质遥感反演及时空变化分析

在同步历史实测数据较为缺乏的条件下,基于波谱特征的比值法可以有效进行水体叶绿素a(Chla)和悬浮颗粒物(Tss)浓度的反演。利用不同时期的Landsat遥感卫星影像对九龙江下游河段的叶绿素a和悬浮颗粒物浓度进行了年际变化分析及季节变化分析发现:较高的叶绿素a浓度主要出现在北溪浦南段(北8北9)以及石龟头至北11段,叶绿素a在枯水期呈现浓度增大的趋势;高悬浮颗粒物浓度较易出现在龙津溪入口(北9郭坑公路桥)河段,高悬浮颗粒物浓度季节主要发生在丰水季节。     

Radiometric mapping of the Berg River estuary

Geographic Information Systems (GIS) consists of various tools to perform spatial analyses in a wide variety of disciplines, including radiometric analysis to characterize the distribution of natural radionuclide concentrations. Recently, open-source GIS has become popular among geospatial users because it can be freely used, and powerful tools are constantly developed to enhance software capabilities. Gamma-ray spectroscopy was used to measure the concentrations of these natural radionuclides by dragging a Delta Underwater Gamma System (DUGS) among the sediment in the Berg River estuary located in Velddrif, South Africa. In this study, QGIS was used to visually illustrate and interpret the distribution of natural radionuclides, that is, potassium (K⁴⁰), thorium (Th²³²), and uranium (U²³⁸). These concentrations can be used to investigate various geographical and geological phenomena, which include sediment processes. The data were then interpreted to derive sediment characteristics. Various features of tidal estuaries were demonstrated by the results.     

中分辨率遥感图像条带噪声的去除

CMODIS是中国第一个发射上天的中分辨率成像光谱仪 ,它有 34个波段 ,波长范围从可见光到红外波段。CMODIS数据含有大量有很高实用价值的光谱信息。但是由于CMODIS传感器之间对接受的地物辐射信号的响应特性不同导致CMODIS数据中的许多波段含有大量的条带噪声 ,严重影响了CMODIS数据的解译和信息提取。在介绍了几种常用于TM ,MSS ,SPOT等多传感器遥感图像中的条带噪声去除方法基础上 ,提出了一种新的有限长脉冲响应滤波 (FIR)法 ,并比较了该方法和其它几种常用方法对几何纠正前后非均匀地物分布的CMODIS数据的去条带噪声结果。结果表明这种新方法要优于本文中提到的几种常用方法 ,具有很好的去条带噪声效果 ,同时保持图像原有信息。这种方法在其它多传感器遥感图像的条带噪声去除中也有很强的适用性。     

Scaling Effects on MODIS Band Ratio of 645 to 859 nm Aggregated from 250 m to 1 km Resolution: A Case Study in Yellow River Estuary

In this study, a theoretical model for studying the scaling effects on the two-band ratio of red to near-infrared band (TBRRN) is suggested. The model is used to explain the relationship between scaling error and local scale error; the results revealed that a special scale scaling procedure can be divided into a series smaller scale scaling procedures, and the total scaling error is the sum of the scaling error of these series’ smaller scale scaling procedure. Consequently, under the condition that the local scale is adequately fine, the total scale error at the target scale may be estimated accurately. In order to understand the mechanisms associated with scale in practical remote sensing, TBRRN data with 250 m and 1 km resolution is estimated from MODIS data at 645 and 859 nm, retrieved on September 1, 2009, in the Yellow River estuary, China. It is found that the TBRRN estimated from the 1 km resolution MODIS data is ~2.94 % smaller than as estimated from the 250 m MODIS data. The large scaling error distributes neither in the turbid waters, nor in the low suspended sediment regions, but instead in the high-low suspended sediment concentration transitional zone, which may be attributed to the spatial variable of suspended sediment in the transitional zone. This paper also points out that, owing to the importance of total scale error in achieving NASA’s mission in oceanic remote sensing, the way in which to conveniently and precisely estimate the total scale error of remote sensing parameters may potentially be an important topic in the field of oceanic remote sensing, both in present research and in the future.     

Spectral characteristics of sediment laden water

A Laboratory experiment has been conducted to establish relation between absolute percent reflectance as measured by Exotech spectro-radiometer compatible to LANDSAT MSS and corresponding known sediment concentrations in a specially designed laboratory sedimentation tank under known illumination conditions. Sediment samples are collected from the bed load deposits of JAYAKWADI reservoir by using a bed load sampler and are analysed in the laboratory for their particle size distribution. Sediment concentrations in the range of 50–1100 mg/l are used in the experiment. A multiple linear regression equation has been developed between absolute percent reflectance and sediment concentration. The results indicate that diffused absolute reflectance from water volume increases with increased sediment concentration and separability between bands is higher at higher concentrations. Exotech band 2 provides significant response from suspended sediment concentrations. There is almost one to one correspondence between predicted (from the model) suspended sediment concentrations and actual concentrations with a coefficient of determination of 0.962 and a standard eror of estimate of 56.47 mg/l. This may be due to the fact that most of the noise sources are nearly eliminated in the controlled laboratory experiment.