青藏高原湖泊现代变化遥感方法研究

我国青藏高原分布着地球上海拔最高、数量最多、面积最大的高原湖群。据统计, 仅青藏高原面积大于1. 0 km ² 的湖泊就有1 091 个, 总面积约44 993. 3 km², 约占全国湖泊总面积的49. 4%。青藏高原湖泊不仅是青藏高原水循环的一个关键因子, 也是青藏高原生态环境的重要要素, 青藏高原湖泊的变化是气候变化敏感的指示器。在全球气候变暖的影响下, 对气候反应敏感的冰川和冻土都在退缩和融化, 青藏高原的湖泊也有明显的响应。青藏高原自然条件恶劣, 交通不便, 数据采集困难。卫星遥感技术是探测湖泊的先进手段, 随着遥感资料的日益丰富, 应用遥感手段研究湖泊变化是可取的方法。1970～2000 年以来的地形图、航空相片和多时相TM 卫星遥感资料, 建立湖泊现代变化遥感综合分析方法, 并对青藏高原南部的羊卓雍湖和沉错等湖泊的变化进行了分析。结果表明, 用遥感方法研究湖泊变化是可行的; 在1970～2000 年期间, 地处青藏高原南部的羊卓雍湖和沉错湖都呈萎缩趋势, 但在1990～2000 年期间有微弱的扩大趋势。     

星载激光雷达在青藏高原湖泊变迁中的应用研究

基于ICESat GLAS数据,结合气温和降水地面观测数据,利用ANUSPLINE空间内插法和Theil-Sen’s中值斜率法,分析探讨HY 2003~2010年青藏高原湖泊水位变化特点及其对气候变化的时空响应特征。结果表明:青藏高原大部分湖泊水位集中在4 500~5 000m,主要分布在青藏高原的中部和西部地区,该地区湖泊水位变化十分剧烈,部分湖泊水位上升十分明显。高原南部的打加错、羊卓雍错和高原西部的班公错的湖泊水位下降趋势显著。同时,不同流域的湖泊水位随着气温和降水的变化而呈现出不同的变化趋势,湖泊水量的增加除依靠降水的直接补给外,也会受由温度变暖引起的积雪融水增加的影响。     

新一代海洋遥感水色传感器展望

一、水色遥感机理和遥感水色传感器的现状浮游植物生长引起的水色变化,是研究渔业和海洋生态的重要依据。海洋表层叶绿素α的浓度是海洋初级生产力的重要指数,是海洋食物链中的重要一环。几十年来海洋生物学家采用常规调查船方法进行水色调查和研究。由于遥感技术的发展,近十几年来科学家开始应用空间遥感手段获得全球性大洋水色几何分布图和随时间变化的分布图,从而发现浮游植物的     

基于自适应加权平均的水色遥感数据融合

水色遥感数据在海洋生产力评估、海洋污染监测等领域中应用广泛,但是受云雨天气、太阳耀斑、纬度位置、轨道间隙的影响,单一的水色遥感数据日均覆盖率只能达到10%～15%甚至更少,导致水色遥感技术在海洋领域的应用受到限制。水色遥感数据融合通过对不同水色传感器数据进行整合,使融合数据比单一传感器数据具有更好的空间覆盖和时间覆盖。选择中国东海为研究区域,首先对不同水色传感器的叶绿素浓度数据进行比较,证明同一天不同传感器数据一致性良好,在空间覆盖上既互相重叠又形成互补关系,保证了数据融合的可行性。在业务化运行的加权平均算法的基础上,提出了利用窗口中各数据源有效像元所占的比例来确定其对应权值的自适应加权平均融合算法。目视判别和统计分析结果表明,该算法能够较好地保持源数据细节特征,保证不同数据覆盖区域间的数据连续性,降低数据源噪声,提高数据空间覆盖率和置信度。     

遥感湖泊面积MTMF提取方法及空间尺度效应研究

主要研究遥感湖泊面积亚像元分解提取方法和空间尺度效应,为遥感湖泊面积提取、检验及基于此的局地气候变化分析提供科学的基础数据。在对TM遥感数据进行升尺度处理的基础上,采用混合调制匹配滤波(Mixture Tuned Matched Filtering,MTMF)进行亚像元分解,得到不同空间分辨率的湖泊面积。进而分析不同面积湖泊随遥感空间尺度的变化。结果表明:(1)当通过对高空间分辨率的遥感数据重采样获取多尺度遥感影像进行湖泊面积提取及湖泊空间尺度效应分析时,采用最近邻法比像元聚合重采样法更合理。(2)MTMF亚像元分解法可以用于基于水体光谱特征的遥感湖泊边界提取和面积计算,但边界提取过程中容易将湖泊与河流或其他非湖泊的水体混淆。(3)遥感湖泊面积的提取结果受所用遥感影像空间分辨率的影响较大,影像的空间分辨率越低,湖泊面积提取的偏差越大,尤其对面积较小的湖泊。     

世界海洋卫星的发射现状

世界海洋卫星包括 :海洋水色卫星、海洋地形卫星和海洋环境卫星。海洋水色卫星是通过星上装载的遥感设备对海洋水色要素进行探测 ,为海洋生物资源开发利用、海洋污染监测与防治、海岸带资源开发和海洋科学研究等提供科学依据和基础数据。最具代表性的海洋水色卫星是 1 997年 8月 1日美国宇航局成功发射的专用海洋水色卫星 "海星 " ,它标志着因水色遥感器 "沿海水色扫描仪 "在 1 986年停止运转而中断了 1 0年的全球海洋水色遥感数据又得以继续 ,而且可以得到质量更高的海洋水色资料。美国计划自 "海星 "卫星发射开始 ,进行 2 0年时序全球海洋…     

青藏高原不同气候子区典型湖泊多时间尺度变化的遥感对比研究

青藏高原湖泊作为气候变化的重要指示器,监测高原湖泊水位变化对于准确评估该地区的气候及其对周围水文与环境的影响至关重要.而由于青藏高原地理环境复杂且恶劣,难以对湖泊进行长时间、连续的实地观测,但遥感技术的发展弥补了这个不足.利用多源测高卫星数据可以有效地监测湖泊水位长时序连续变化,促进对青藏高原湖泊气候变化响应特征的理解...     

珠海一号欧比特高光谱数据交叉辐射定标初探

搭载于“珠海一号”卫星星座的欧比特高光谱OHS（Orbit Hyper Spectral）传感器,以较高的光谱分辨率和空间分辨率,在近岸及内陆湖泊水色遥感应用方面具有很大潜力。然而OHS缺乏星上定标系统,目前在轨定标采用陆地定标场的资料,其定标结果在水体等低反射率地物误差较大。因此提出一种基于传感器入瞳总辐亮度的交叉辐射定标法,该方法结合QAA（Quasi-Analytical Algorithm）准分析算法和6SV2.1辐射传输模型,利用GOCI（Geostationary Ocean Color Imager）多光谱数据对OHS高光谱数据进行交叉辐射定标。研究结果表明：①GOCI和OHS传感器获取的地物辐射相关性好,在可见光波段范围内,R²均高于0.84;②重新定标后的数据能明显改善不同传感器之间的辐射差异,在可见光波段范围内,定标误差小于9%。实验为高光谱传感器的辐射定标提供了一种新的方法,对建立高光谱定量化、业务化水色遥感处理系统,特别对OHS数据在水域的各种应用具有重要意义。     

面向湖泊水色监测的卫星遥感成像仿真初步研究——基于Hyperion场景

成像过程仿真是论证面向二类水体水色监测卫星遥感系统的必要环节。本文设定了面向湖泊水色监测的卫星遥感概念系统的性能和技术参数,在此基础上基于Hyperion场景开展对该系统的仿真初步研究。在地表场景仿真中,通过大气校正、线性光谱内插和光谱卷积等过程获得地表辐射场景;在大气辐射传输仿真中,根据成像系统和大气状况参数建立了大气查找表;在传感器系统仿真中,基于等效电子法理论建立了信噪比模型并经过线性数字量化输出了仿真数字图像和信噪比图像。研究结果表明:(1)仿真数字影像较好地重现了原始场景中的几何和辐射信息;(2)受大气程辐射的影响,信噪比随波长增加而增大;(3)信噪比在概念系统的前3个波段上小于400∶1,而在其他波段上高于400∶1,采用时间延迟积分技术可以达到二类水体水色监测对辐射灵敏度的要求。     

EASE-Grid投影对青藏高原雪水当量产品的验证影响分析

本文介绍EASE-Grid 3种投影的定义,利用地面实测数据和理论方式开展不同投影下AMSR-E雪水当量(SWE)产品的精度验证对比分析,研究其不同投影导致误差产生的原因。验证对比结果表明,青藏高原地区北半球方位角等积投影和全球圆柱体等积投影对于验证结果具有很大影响。理论分析结果表明,我国青藏高原地区在全球圆柱体等积投影下网格发生的形变较小,更适合采用全球圆柱体等积投影。进一步研究表明,AMSR-E亮温数据轨道采样点落入北半球方位角等积投影和全球圆柱体等积投影对应网格差异较大。雪水当量产品验证结果的误差包含了算法误差和投影带来的误差。在开展大尺度遥感反演时,应根据具体研究区所处的纬度范围及研究目的,选取适合的投影方式以降低投影引起的误差。     

智慧巡湖系统在湖泊管理中的探索应用

针对湖泊人工巡查方面存在的巡查效率低下、管理不全面、分工不到位、问题追踪更新不及时等问题,提出利用无人机智慧巡检方式,通过无人机沿湖泊岸线航拍提取大量图像,利用 SIFT 算法完成图像无缝拼接,提取图像主要目标区域,并利用 SIFT 特征完成目标图像与原始图像的比对,从而识别湖泊岸线变化情况。 该方法应用在石臼湖固城湖湖泊巡查中,无人机初次飞行时提取湖泊网格地理数据及建筑物构筑物的信息作为原始数据,完成 2 期巡检,覆盖范围和识别精度较人工巡查有很大提高。在实际应用中发现在水生物识别的细节和巡查频次上还有待提高,目前作为湖泊辅助性巡查上优势明显,作为一种独立的巡查方式及在智能分析决策上值得进一步探讨。     

Absorption and scattering properties of water body in Taihu Lake,China: absorption

In order to acquire inherent optical properties to serve the lake water colour/quality remote sensing in Taihu Lake 67 samples were distributed almost all over the lake. Surface water samples were collected and returned to the laboratory for the subsequent processing and analysis. In the laboratory, the absorptions due to the total particulate matter, non‐algal particulate matter, phytoplankton pigment, and CDOM, together with their concentrations were measured and/or calculated, respectively. Then their absorption properties were analysed and compared with those of other lake waters and/or coastal/open waters. Some different and similar characteristics were uncovered. On the one hand, it provides not only a solid basement for the Taihu Lake water colour/quality remote sensing with semi‐analytical/analytical approach but also a typical case for inherent optical properties of case two water especially for inland freshwater lakes. On the other, it is very helpful to improve the practical and intensive application and development of remote sensing in monitoring lake water quality.     

Evaluation of four MERIS atmospheric correction algorithms in Lake Kasumigaura,Japan

Accurate atmospheric correction for turbid inland waters remains a significant challenge. Several atmospheric correction algorithms have been proposed to address this issue, but their performance is unclear in regard to Asian lakes, some of which have extremely high turbidity and different inherent optical properties from lakes in other continents. Here, four existing atmospheric correction algorithms were tested in Lake Kasumigaura, Japan (an extremely turbid inland lake), using in situ water-leaving reflectance and concurrently acquired medium resolution imaging spectrometer (MERIS) images. The four algorithms are (1) GWI (the standard Gordon and Wang algorithm with an iterative process and a bio-optical model) (2) MUMM (Management Unit of the North Sea Mathematical Models); (3) SCAPE-M (Self-Contained Atmospheric Parameters Estimation for MERIS Data) and (4) C2WP (Case-2 Water Processor). The results show that all four atmospheric correction algorithms have limitations in Lake Kasumigaura, even though SCAPE-M and MUMM gave acceptable accuracy for atmospheric correction in several cases (relative errors less than 30% for the 2006 and 2008 images). The poor performance occurred because the conditions in Lake Kasumigaura (i.e. the atmospheric state and/or turbidity) did not always meet the assumptions in each atmospheric correction algorithm (e.g. in 2010, the relative errors ranged from 42% to 83%). These results indicate that further improvements are necessary to address the issue of atmospheric correction for turbid inland waters such as Lake Kasumigaura, Japan.     

Remote sensing of algal blooms by aircraft and satellite in Lake Erie and Utah Lake

During late summer, when the surface waters of Lake Erie reach their maximum temperature, an algal bloom is likely to develop. Such phenomena, which characterize eutrophic conditions, have been noticed on other shallow lakes using the Earth Resources Technology Satellite (ERTS-1). The concentration of the algae into long streamers provides additional information on surface circulations. To augment the ERTS Multispectral Scanner Subsystem (MSS) data of Lake Erie an aircraft was used to obtain correlative thermal-IR and additional multiband photographs. The algal bloom is highly absorptive in the visible wavelengths but reverses contrast with the surrounding water in the near-IR bands. The absorption of shortwave energy heats the dark brown algal mass, providing a hot surface target for the thermal-IR scanner. A large bloom of Aphanizomenon flos-aquae observed in Utah Lake together with recent bloom history in Lake Erie is used to verify the Great Lakes bloom.     

Variability in ice phenology on Great Bear Lake and Great Slave Lake, Northwest Territories, Canada, from SeaWinds/QuikSCAT: 2000-2006

The temporal evolution of the backscatter coefficient, sigma-nought (σ°) from QuikSCAT was evaluated for monitoring ice phenology on Great Bear Lake (66°N, 121°W) and Great Slave Lake (61°40′N, 114°W), Northwest Territories, Canada. Results indicated that σ° from QuikSCAT can be used to detect melt onset, water clear of ice and freeze onset dates on both lakes. An ice phenology algorithm was then developed to assess the spatiotemporal variability on both lakes from QuikSCAT for the period 2000-2006. Results showed that for Great Slave Lake, the average melt onset date occurred on year day (YD) 123, the average water clear of ice date was on YD164, and the average freeze onset date was on YD330. On Great Bear Lake, the average melt onset date occurred on YD139, the average water clear of ice date was YD191, and the average freeze onset date was YD321. Ice cover remained present for at least five weeks longer on Great Bear Lake than on Great Slave Lake and most of the difference can be explained by earlier ice melt on Great Slave Lake. Spatially, on Great Bear Lake, melt onset took place first in the eastern arm, water clear of ice occurred first in southeastern and western arms, and freeze onset appeared first in the northern arm and along the shorelines. On Great Slave Lake, melt onset began first in the central basin and then progressed to the northern and eastern arms later in the season. The central basin of Great Slave Lake cleared earlier than the periphery due to the discharge from the Slave River. Freeze onset on Great Slave Lake occurred first within the east arm, closely followed by the north and west arms, and then finally in the centre of the main basin.     

基于WebGIS的湖北省湖泊时空演变系统设计与实现

位于长江中游的湖北省,分布有丰富广阔的湖泊资源,有着"千湖之省"的美誉.近年来水系自然演变和人类活动的影响使得湖泊面积变化显著.为充分了解湖北省湖泊变迁,文章利用WebGIS的空间信息处理功能、数据库等关键技术,设计建立湖北省湖泊信息数据库,实现对湖北省湖泊基本情况的时空演变的展示.系统可提供对湖北省湖泊信息的存储管理...     

基于TM 影像和DEM 的白碱湖湖面变化模拟

史前时期, 在石羊河下游存在着一个面积广大的统一终端湖--猪野泽, 随着气候的变化和人类活动的加剧, 猪野泽逐渐分裂、瓦解并最后完全干涸, 遗留下众多的终端湖残迹, 白碱湖为其中规模最大、干涸最晚者。以TM 遥感影像为数据源, 通过影像增强, 突出了白碱湖北岸岸坡上呈水平平行状分布的一组色调相间变化的条带。经过判读、对比分析和在GPS 导航下的实地考察, 其中的8 条被确认为曾经的湖岸线。利用该地区1∶5 万DEM , 读取这些湖岸线现代条件下的高程, 并在GIS 中对各湖岸线相应的湖面面积和水量进行了计算。结果表明, 白碱湖湖面的最高高程约1 320 m , 相应的最大湖面面积为1 600 km ², 其后经历过多次规模不等的退缩, 直至上个世纪完全干涸。     

ADCP测流在巢湖流域水资源监测中的应用

为满足巢湖湖(河)长制考核验收的需要,需对巢湖43个考核断面建设水资源监测站,对ADCP测流技术,以及走航式、水平式和垂线式3种测流设备进行介绍和比较,根据各种测流设备的适用范围和测流断面的特征,选择合适的建设方案,方案实施后,可以实现水质和水量同步监测,控制河流入湖污染总量,为湖(河)长制考核验收提供数据支持。     

Satellite-derived evaporation from Lake Eyre,South Australia

Abstract

Lake Eyre is a large salt lake situated on the Australian continent, draining an area of over 1 million km². The lake is usually dry, but it floods occasionally; the last few significant events occurring in 1984, 1974 and 1950. During the 1984 filling, satellite data from NOAA Advanced Very High Resolution Radiometer (AVHRR) were received and archived. These data have now been analysed to derive the areal extent of standing water as a function of time and hence the evaporation rate, assuming exchanges due to groundwater flow and gains due to rainfall and runoff are negligibly small. The highest levels were reached on 3 February 1984 and the lake was dry by the end of March 1985. Maximum evaporation of 280 mm occurred in February 1984 and a minimum of 60 mm occurred in July 1984. The total evaporation for the period February 1984 to February 1985 is estimated to be 2190 mm ± 100 mm for Lake Eyre North and 1980 mm ± 110 mm for Lake Eyre South. These estimates compare favourably with field data collected over the same period. It is suggested that the satellite data could provide a reasonable estimate of evaporation from shallow lakes in other semi-arid, inaccessible regions.     

Study on Lake Izvorul Muntelui rehabilitation

In the actual economical and ecological context the rehabilitation of aquatic ecosystems represents one of the most important concerns all over the world. The physical, chemical and biological processes that take place inside a lake are very complex. A simple analysis of the field data is not enough. Even if those dates offers an appreciation of the global functioning of the ecosystem under the influence of certain factors, it does not allow to predict the system evolution, the optimization of the water arrangement, in order to respect and to assure the water quality criteria or to propose solutions for diminishing the lakes eutrophication.In the recent years, Lake Izvorul Muntelui, which is the largest artificial lake on the interior waters of Romania, experienced eutrophication problems. This paper analyzes the apparition condition, its effects onto water quality in the lake and the solutions for the rehabilitation of the ecosystem. Since systematic measured data are not available for this ecosystem, the mathematical modelling it is used.The simulation is done by considering the ecosystem dynamic and the stipulation of the spatial and temporal variation domains for the natural processes to appear and act onto perturbation factors to modify the ecological succession.Thus, different scenarios will be created allowing us to offer solutions for the eutrophication phenomenon and, in the same time, to identify solutions for the rehabilitation of the Izvorul Muntelui Lake.