Remote sensing and information value (IV) model for regional mapping of fluvial channels and topographic wetness in the Saudi Arabia

This study aims to map regions of near surface fluvial channels, mega-basins and topographic wetness in Saudi Arabia using remote sensing data and an information value (IV) model, which is a modified approach of weight of evidence. We used the new version of the Shuttle Radar Topographic Mission (SRTM) to delineate the fluvial channels, mega-basin, and slope. These hydrological parameters were used to index the topographic wetness of each mega-basin in the region based on IV in a Geographic Information System. We validated our method using the Space Imaging Radar-C and Landsat 8 images and compared the textural features (fluvial channels) evident from SRTM digital elevation model and to determine whether these patterns were different. Our results revealed that the region is drained by nine tributaries and that the Err Rub Al Khali and Sahba mega-basins have the highest value of the IV and topographic wetness values; the Arran and coastal mega-basins have the lowest value of the IV and topographic wetness values. An integrated approach is timely and economically effective and can be applied throughout the arid and semi-arid regions to help hydrologists and urban developers.     

Discriminating lava flows of different age within Nyamuragira’s volcanic field using spectral mixture analysis

In this study, linear spectral mixture analysis (LSMA) is used to characterize the spectral heterogeneity of lava flows from Nyamuragira volcano, Democratic Republic of Congo, where vegetation and lava are the two main land covers. In order to estimate fractions of vegetation and lava through satellite remote sensing, we made use of 30 m resolution Landsat Enhanced Thematic Mapper Plus (ETM+) and Advanced Land Imager (ALI) imagery. 2 m Pleiades data was used for validation. From the results, we conclude that (1) LSMA is capable of characterizing volcanic fields and discriminating between different types of lava surfaces; (2) three lava endmembers can be identified as lava of old, intermediate and young age, corresponding to different stages in lichen growth and chemical weathering; (3) a strong relationship is observed between vegetation fraction and lava age, where vegetation at Nyamuragira starts to significantly colonize lava flows ∼15 years after eruption and occupies over 50% of the lava surfaces ∼40 years after eruption. Our study demonstrates the capability of spectral unmixing to characterize lava surfaces and vegetation colonization over time, which is particularly useful for poorly known volcanoes or those not accessible for physical or political reasons.     

Spectral properties of volcanic materials from hyperspectral field and satellite data compared with LiDAR data at Mt. Etna

Spectral properties of volcanic materials in the optical region (350–2500 nm) of the electromagnetic spectrum are analyzed. The goal is to characterize air-fall deposits, recent lava flows, and old lava flows based on their spectral reflectance properties and on the textural characteristics (grain size) of pyroclastic deposits at an active basaltic volcano. Data were acquired during a spectroradiometric field survey at Mt. Etna (Italy) in summer 2003 and combined with hyperspectral satellite (Hyperion) and airborne LiDAR (Light Detection and Ranging) data. In addition, air-fall deposits produced by the highly explosive 2002–2003 eruption have been sampled and spectrally characterized at different distances from the new vents. The spectral analysis shows that air-fall deposits are characterized by low reflectance values besides variations in grain size. This distinguishes them from other surface materials. Old lava flows show highest reflectance values due to weathering and vegetation cover. The spectral data set derived from the field survey has been compared to corrected satellite hyperspectral data in order to investigate the Hyperion capabilities to differentiate the surface cover using the reflectance properties. This has allowed us to identify the 2002–2003 air-fall deposits in a thematic image just few months after their emplacement. Moreover, the observed differences in the field spectra of volcanic surfaces have been compared with differences in the signal intensity detected by airborne LiDAR survey showing the possibility to include information on the texture of volcanic surfaces at Mt. Etna. The approach presented here may be particularly useful for remote and inaccessible volcanic areas and also represents a potentially powerful tool for the exploration of extraterrestrial volcanic surfaces.     

2022年汤加火山喷发的综合遥感快速解译分析

2022年1月14日—15日南太平洋汤加Hunga Tonga-Hunga Ha'apai(HTHH)海底火山发生剧烈喷发并造成海啸,引起了国际广泛关注.对此次"千年一遇"的汤加HTHH火山喷发事件进行应急响应,首先综合利用国内外多时相卫星光学影像、雷达影像、全球导航卫星系统(global navigation sat...     

Retrieval of land surface temperature and emissivity from satellite data: Physics, theoretical limitations and current methods

Remote sensing from satellites is the only means to obtain land surface temperature (LST) and emissivity on a larger scale. LST has many applications, e.g., in radiation budget experiments and global warming, and desertification studies. Over the last decades, substantial amount of research was dedicated towards extracting LST and emissivity from surface-leaving radiance and de-coupling the two from each other. This paper provides the physical basis, discusses theoretical limitations, and gives an overview of the current methods for space-borne passive sensors operating in the infrared range, e.g., NOAA-AVHRR, Meteosat, ERS-ATSR, TERRA-MODIS, and TERRA-ASTER. Atmospheric effects on estimated LST are described and atmospheric-correction using a radiative transfer model (RTM) is explained. The methods discussed are the single channel method, the split window techniques (SWTs), and the multi-angle method.     

Geologic remote sensing for geothermal exploration: A review

This paper is a comprehensive review of the potential for remote sensing in exploring for geothermal resources. Temperature gradients in the earth crust are typically 25–30 °C per kilometer depth, however in active volcanic areas situated in subduction or rift zones gradients of up to 150 °C per kilometer depth can be reached. In such volcanic areas, meteoric water in permeable and porous rocks is heated and hot water is trapped to form a geothermal reservoir. At the Earth's surface hot springs and fumaroles are evidence of hot geothermal water. In low enthalpy systems the heat can be used for heating/cooling and drying while in high enthalpy systems energy is generated using hot water or steam. In this paper we review the potential of remote sensing in the exploration for geothermal resources. We embark from the traditional suite of geophysical and geochemical prospecting techniques to arrive at parameters at the Earth surface that can be measured by earth observing satellites. Next, we summarize direct and indirect detection of geothermal potential using alteration mineralogy, temperature anomalies and heat fluxes, geobotanical anomalies and Earth surface deformation. A section of this paper is dedicated to published remote sensing studies illustrating the principles of mapping: surface deformation, gaseous emissions, mineral mapping, heat flux measurements, temperature mapping and geobotany. In a case study from the La Pacana caldera (Chili) geothermal field we illustrate the cross cutting relationships between various surface manifestations of geothermal reservoirs and how remotely sensed indicators can contribute to exploration. We conclude that although remote sensing of geothermal systems has not reached full maturity, there is great potential for integrating these surface measurements in a exploration framework. A number of recommendations for future research result from our analysis of geothermal systems and the present contributions of remote sensing to studying these systems. These are grouped along a number of question lines: ‘how reproducible are remote sensing products’, ‘can long term monitoring of geothermal systems be achieved’ and ‘do surface manifestations link to subsurface features’?     

Detecting anomalous CO2 flux using space borne spectroscopy

Over the time-scale, earth's atmospheric CO₂ concentration has varied and that is mostly determined by balance among the geochemical processes including burial of organic carbon in sediments, silicate rock weathering and volcanic activity. The best recorded atmospheric CO₂ variability is derived from Vostok ice core that records last four glacial/interglacial cycles. The present CO₂ concentration of earth's atmosphere has exceeded far that it was predicted from the ice core data. Other than rapid industrialization and urbanization since last century, geo-natural hazards such as volcanic activity, leakage from hydrocarbon reservoirs and spontaneous combustion of coal contribute a considerable amount of CO₂ to the atmosphere. Spontaneous combustion of coal is common occurrence in most coal producing countries and sometimes it could be in an enormous scale. Remote sensing has already proved to be a significant tool in coalfire identification and monitoring studies. However, coalfire related CO₂ quantification from remote sensing data has not endeavoured yet by scientific communities because of low spectral resolution of commercially available remote sensing data and relatively sparse CO₂ plume than other geological hazards like volcanic activity. The present research has attempted two methods to identify the CO₂ flux emitted from coalfires in a coalmining region in north China. Firstly, a band rationing method was used for column atmospheric retrieval of CO₂ and secondly atmospheric models were simulated in fast atmospheric signature code (FASCOD) to understand the local radiation transport and then the model was implemented with the inputs from hyperspectral remote sensing data. It was observed that retrieval of columnar abundance of CO₂ with the band rationing method is faster as less simulation required in FASCOD. Alternatively, the inversion model could retrieve CO₂ concentration from a (certain) source because it excludes the uncertainties in the higher altitude.     

大气CO2浓度卫星遥感进展

大气CO2是重要的温室气体,CO2浓度及其空间分布是全球气候变化评估中的主要不确定性因素之一。从1998年以来,卫星遥感大气CO2成为获取全球CO2的重要手段。本文阐述了现阶段大气CO2浓度卫星遥感反演进展情况,包括CO2探测载荷、反演算法和算法验证等。同时,论文详细介绍了近红外波段和热红外波段的反演算法特点和不确定因素,并针对CO2反演应用需求提出了展望。     

Change detection from remotely sensed images: From pixel-based to object-based approaches

The appetite for up-to-date information about earth’s surface is ever increasing, as such information provides a base for a large number of applications, including local, regional and global resources monitoring, land-cover and land-use change monitoring, and environmental studies. The data from remote sensing satellites provide opportunities to acquire information about land at varying resolutions and has been widely used for change detection studies. A large number of change detection methodologies and techniques, utilizing remotely sensed data, have been developed, and newer techniques are still emerging. This paper begins with a discussion of the traditionally pixel-based and (mostly) statistics-oriented change detection techniques which focus mainly on the spectral values and mostly ignore the spatial context. This is succeeded by a review of object-based change detection techniques. Finally there is a brief discussion of spatial data mining techniques in image processing and change detection from remote sensing data. The merits and issues of different techniques are compared. The importance of the exponential increase in the image data volume and multiple sensors and associated challenges on the development of change detection techniques are highlighted. With the wide use of very-high-resolution (VHR) remotely sensed images, object-based methods and data mining techniques may have more potential in change detection.     

Evaluation and use of Resourcesat-I data for agricultural applications

Resourcesat-1 satellite offers a unique opportunity of simultaneous observations at three different spatial scales through LISS-IV, LISS-III^* (improved LISS-III) and AWiFS sensors from a common platform. The sensors have enhanced capabilities in terms of spectral, spatial and radiometric resolution as compared to earlier Indian Remote sensing Satellite sensors. This paper summarizes the results of various studies such as evaluation of sensor characteristics, inter-sensor comparison studies, derivation and validation of surface reflectance measurements, quantification of improvements due to Resourcesat-1 sensors, and their use for various agricultural applications. The studies presented in this paper demonstrate that suit of sensors onboard Resourcesat-1 satellite provides better prospects for several agricultural applications like crop identification, discrimination and crop inventory for some major Indian crops, than its predecessors on IRS satellites.     

地表不透水面信息遥感的主要方法分析

全球范围内的城市扩张已使得大量的不透水面取代了以植被为主的地表自然景观,并给生态环境带来了明显的负面影响。不透水面作为一个影响生态环境的关键因子已引起了全社会的广泛关注。如何及时快速地掌握不透水面的空间分布信息,准确无误地量化不透水面的动态变化信息,是城市规划、环境保护亟待解决的现实问题。而遥感以其快速、大范围、多尺度、可重复的对地观测优势为解决这一问题提供了很好的解决方案。不透水面遥感研究经过近十几年的发展已有了长足的进步,多种针对不透水面信息反演的遥感创新技术与方法被相继提出。本文重点分析了这些针对遥感不透水面提出的创新技术,详细地指出了它们的优势和不足,并在此基础上总结了中国遥感工作者在不透水面遥感方面的研究工作。当前许多不透水面信息的反演精度都可以达到85%以上,但是不透水面与裸土和阴影信息的混淆仍是困扰不透水面信息精准反演的主要问题。由于大部分不透水面材料具有和砂土石同源的特点,因此在现有影像光谱分辨率不足的情况下,单靠光谱是很难进一步提高不透水面信息的反演精度,而借助LiDAR等其他辅助数据,将有望帮助解决这一瓶颈问题。     

Volcanic ash detection by GPS signal

We investigate the ability of GPS to detect volcanic plumes at Mt. Etna, Italy. We use a robust statistical approach to highlight whether the presence of a volcanic plume in the atmosphere may really affect the GPS undifferenced post-fit phase residuals. The proposed method has been tested for the September 4–5, 2007 activity of Mt. Etna. This eruption produced powerful lava fountains forming a weak, a few kilometers high plume for several hours, representing typical activity at Etna over the last 5 years. We analyzed data from nineteen Etna permanent GPS stations located on the volcano flanks at different heights and applied a statistical test based on four main steps: (a) realization of a simplified model representing the volcanic plume in atmosphere; (b) evaluation of the GPS satellite and station couples intersecting the plume; (c) calculation of the volcanic plume region crossed by the GPS signal; (d) application of a robust statistical test in order to see whether the volcanic plume affected the GPS signals. Results show that during the September 4–5, 2007 explosive activity, the GPS residuals definitely include the contribution of the volcanic plume. Our analysis shows that values of the GPS residuals are ten times smaller than those found for the Miyakejima eruption (Japan), highlighting a likely relationship between residuals and eruption intensity. In the future, data derived from the GPS stations located on Etna’s flanks could be used to improve the alerting system of volcanic ash, already operating at the Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Etneo.     

基于整数小波变换的多光谱图像无损压缩

多光谱图像一般都采用预测方法去除空间冗余和谱内冗余实现无损压缩。通过用提升方法构造整数小波变换, 将变换方法用于去除空间冗余；通过分类方法构造谱间预测器，用预测方法去除谱间冗余，两者相结合，实现无损压缩。由于变换方法的去相关性能良好，使该方法压缩效果大大改善。     

MONITORING OF ACTIVE VOLCANOES ON KAMCHATKA FROM THERMAL INFRARED SCANNER AND RADAR IMAGERY

On the basis of data recorded by a thermal infrared multispectral scanner (TIMS) carried on board an aircraft laboratory, maps of volcanic regions in Russia were compiled on which portions of lava dating to different periods were identified. SIR-C (Shuttle) data, processed by computer, made it possible to obtain distinct boundaries of lava flows with cross-polarization. A three-dimensional digital model of the Northern Fissure of the Great Tolbachik Fissure Eruption, on which TIMS, Zeiss, and SIR-C data were plotted, was constructed. A lineament analysis was made it possible to genetically classify cinder cones on the eastern slope of the Klyuchevskoy volcano, and a zone of areal volcanism was defined.     

Delineation of ground water potential zones in a hard rock terrain of Mysore district, Karnataka using IRS data and GIS techniques

In the present study, the ground water prospect of Mysore district has been delineated using remotely sensing data, base map of GSI, ground truth data, and geographic information system. Based on these integrated studies, it has been noticed that the lithology of the area mainly represents by amphibolite schists, hornblende-biotite gneiss, chamockite, quartzite and granite belonging to Archean to Lower Proterozoic. Resent alluvial deposits mainly occur as valley fills. Major lineaments are mainly confined to valley regions. Structurally the erosional and depositional landforms are occurring as hills, ridges, weathered pediments, weathered pediplains and valley fills. Geonaorphology, lineaments, drainage density, type of lithology and surface water bodies are directly influencing the ground water conditions and it is very good iu valley regions and in remaining area, it is moderate to poor.     

火星表面含水矿物探测进展

火星表面含水矿物类型识别和空间分布特征研究对圈定火星表面生命活动有利区域和探索可能存在的火星生命形式具有重要科学意义。本文总结了20世纪90年代以来火星表面含水矿物的探测进展,从火星轨道器光谱仪遥感探测、着陆器和巡视器就位探测两方面介绍了矿物探测使用的数据源,重点阐述了目前火星表面已经探测到的各类含水硅酸盐矿物、硫酸盐矿物、碳酸盐矿物、氯盐及高氯酸盐矿物等含水矿物的光谱特征、矿物具体类别及分布特征,分析了火星表面含水矿物定量反演的主要方法与地质意义。最后从比较行星学角度倡议开展地球和火星含水矿物形成环境和形成过程的类比研究。     

数字图像处理技术在煤层火灾遥感调查中的应用

本文介绍在S101图像处理系统上,应用数字图像处理技术提取有关煤层火灾信息的方法,着重介绍从多时相航空、航天热红外遥感图像中,提取地表活火区所使用的图像处理技术及其应用效果。     

High altitude aircraft remote sensing during the 1988 Yellowstone national park wildfires

Abstract

The advancement of satellite remote sensing has offered greater potential for mapping volcanic deposits. Although the development of weather‐independent microwave remote sensing has made the frequent detection over large area detection of deposits using SAR intensity image is sometimes hindered by ambiguities and noise. The ambiguities occur in volcanic deposit areas covered by young vegetation and that give either high or low backscatter depending upon their orientation. For this reason coherent images were integrated with SAR intensity images to extract more reliable information about volcanic deposited area. Besides, the layover areas due to the viewing geometry of SAR make difficulties to map the volcanic deposits on every side of the mountain. To avoid the influence of layover effects fusion techniques of ascending and descending pass SAR intensity and coherent images were developed. Using the fused images with an optical image, a color composite was developed to identify the areas affected by an eruption. In this color composite, especially vegetation damages can be easily identified.     

Groundwater prospects in a developing satellite township of Andhra Pradesh, India, using remote sensing techniques

Geomorphologic map prepared, using the remote sensing techniques and conventional methods, has been used to assess groundwater prospects in a developing satellite township of Visakhapatnam Metropolitan Complex. Andhra Pradesh, India. The geomorphic units delineated are denudational, fluvial and coastal. The study indicates that the fluvial and rolling plains are promising zones for groundwater occurrence. The denudational landforms are not considered as groundwater potential zones, whereas the groundwater occurring in the coastal plain is not suitable for any use, because of its brackish nature.