Remote sensing technique for near-surface wind by optical images of rough water surface

The study of a new remote-sensing technique for the investigation of near-surface wind fields is an important oceanographic problem. This article is focused on a new method of recording wind fields by the analysis of optical images of sea surface and range–time–intensity images (RTI images) of the sea surface. An RTI image constructed from optical profiles of the sea surface is an optical analogue of a side-looking radar image of the sea surface but has a higher spatial resolution and some possibility for remote sensing of sea roughness. It is possible to form RTI images with a range from some tens of metres to tens of kilometres, depending on the spatial resolution needed. A set of original optical devices for recoding RTI images using linear arrays of CCD-photodiodes was created. An analytical model of sea surface radiance for visible light was developed taking into account the polarization of light and shadowing of surface waves for grazing view geometry. The principle of remote sensing of near-surface winds by its manifestations on a waved surface under grazing angles based on a comparison of measured and modelled surface radiance is discussed. Investigations of near-surface wind field features in internal reservoirs and various regions of the seas during the last few years have been conducted by optical systems. The structure of near-surface wind fields, eddies, wind fronts, and katabatic wind flows for ranges from hundreds of metres to some tens of kilometres was recorded and analysed. Derived data of optical monitoring of water surfaces may serve for future investigations of near-surface wind features.     

Remote sensing and GIS activities in UNESCO

The role of UNESCO is to promote international peace and security through cooperation in the fields of education, science and culture. In view of eradicating illiteracy, overcoming unsustainability of natural resources, confronting environmental problems, safeguarding historical monuments, and preserving natural and cultural heritage, UNESCO develops international research programmes and makes best possible use of new advances in technology, namely remote sensing and GIS, in order to effectively carry out activities in the framework of its programmes. Part one describes remote sensing and GIS use in international programmes such as the Man and the Biosphere (MAB) programme for biosphere reserve development and ecosystem monitoring, management and conservation; the International Hydrological Programme (IHP) for surface and ground water research management; the International Geological Correlation Programme (IGCP) for the creation of a data base on the spectral signatures of rocks and soils; and in several projects concerning ocean investigation and climate observation conducted in the framework of the Intergovernmental Oceanographic Commission (IOC). In part two constraints of using the remote sensing and GIS technology are addressed and remaining difficulties in accessing and exchanging data, training issues and costs are discussed.     

Remote sensing of the Indo-Pacific region: ocean colour,sea level,winds and sea surface temperatures

The 1997–1998 ENSO (El Niño-Southern Oscillation) was not only the largest event of the century but also the most comprehensively observed. Satellite data were employed for ocean colour, sea level, winds, sea surface temperature (SST), and outgoing longwave radiation (OLR) were used to describe the response of the surface marine ecosystem associated with the ENSO event. Some of the large-scale anomalies in ocean colour include elevated biological activity to the north of the Equator in the Pacific coincident with lower sea levels associated with the classic ENSO-horseshoe pattern ecosystem response to the anomalous upwelling in the eastern Indian Ocean caused by the 1997–1998 dipole event, and the dramatic eastward propagating feature in the Equatorial Pacific in response to the La Niña dynamics. Ocean general circulation model (OGCM) experiments show that capturing the high-frequency wind changes is crucial for simulating the La Niña and the coupled biological–physical model (OBGCM) runs clearly show that higher frequency winds are also important for capturing the mean upwelling and nutrient supply into the euphotic zone. Thus, the QuickSCAT winds are expected to play a major role in ecosystem modelling in the future. This study shows the utility of satellite data for understanding not only ocean circulation but also the coupled ecosystem variability. Morcover, it is also shown that spatio-temporal resolution of the satellite winds will directly affect the accuracy of oceanic and ecosystem simulations.     

Remote sensing applications in the Australian Bureau of Meteorology

Abstract

The space age for the Bureau of Meteorology arrived in December 1963 with the first direct receipt in Australia of visual images of clouds from the US TIROS-8 satellite. Since that time, the successful application of advances in satellite data, products and services has brought dramatic improvements to most aspects of the Bureau's operations and research. This paper documents the developments of the past 25 years by describing the Bureau's current national infrastructure for the reception, processing and dissemination of meteorological satellite data and the way in which satellite data and systems are used to improve the Bureau's services. The meteorological satellite has emerged not only as a highly cost-effective primary observation platform, providing an increasingly diverse range of meteorological data, but also as a vital communications medium for both general meteorological information and the interrogation of complementary observational systems. The prospects for further major advances in the application of satellite information within the Bureau are very high. During the early 1990s and beyond, the next generation of active remote sensing technology will replace the current passive sensor technology deployed in the international meteorological satellite network. As a result, further improvement in the ability of the Australian meteorological community to describe quantitatively the dynamic and thermodynamic structure of the atmospheric and marine environment is confidently predicted.     

Remote sensing and GIS for an oil spill contingency plan,Ras-Mohammed,Egypt

Ras-Mohammed area located at the southern tip of Sinai, is an important and unique environment which has valuable resources that should be carefully maintained. This area is threatened by numerous anthropogenic activities. The most important risk is that associated with possible oil spills from tankers crossing the Suez canal

The main objective of this study is to prepare an oil spill contingency plan for the study area. SPOT-XS data were used to derive valuable information about the different resources of the area, especially the shallow coral reef communities

SPOT images, ground surveys and GIS analysis have enabled an accurate evaluation of environmental sensitivity. This helped to put forward a proposal of an oil spill contingency plan, in order to protect environmentally sensitive areas such as Ras-Mohammed.     

Remote sensing applications in the Southeast Sumatra coastal environment

The coastal lowland swamps, rivers and estuarine areas north of Palembang, South Sumatra constitute a resource base likely to be extensively exploited during the next several years. Activities such as swamp forest logging, extensive fisheries, movement of government sponsored transmigrants and Buginese settlers into the area have intensified in recent years. Palembang is an important port which is difficult to maintain at sufficient depth to allow use by deep water ships, thereby creating interest in a coastal port location. In the near future it will be necessary to develop a multiple resource use management strategy based on national priorities, local needs and ecological constraints. Landforms, vegetation patterns, sediment and erosion sites, land use dynamics, settlement patterns and albedo are analysed from a time series of aerial photographs and LANDSAT imagery. The results, correlated with field data, indicate patterns of ecological constraints and resource use dynamics that have implications for development over much of the eastern coast of Sumatra.     

Remote sensing and GIS for estimation of irrigation crop water demand

Satellite images supported by global positioning systems (GPS) and field visits were used to identify the cropping pattern of a large irrigation scheme in Central Asia. Two methods were used to estimate the crop evapotranspiration (ET). In the first, the ETs of the different crops were calculated from local field climatic data using the Penman–Monteith method of calculating crop water requirements as used in the Food and Agriculture Organization (FAO) CropWat programme. The satellite data were transferred to a geographical information system (GIS) and the area of each crop type was identified. Combining the two sets of data gave an estimate of ET and total evaporative water demand for each crop. ET was also calculated directly from the satellite data using a modified sensible heat flux approach (SEBAL). The Penman–Monteith approach estimated the ET to be 5.7, 3.3, 4.4 and 6.3?mm?d^?1 for cotton, mixed crop, alfalfa and rice respectively, whereas the ET estimated from the satellite data were 4.4, 3, 3.2 and 5.3?mm?d^?1, respectively. The possible causes of these differences are discussed. The FAO Penman–Monteith methodology for estimating crop water requirements is best for planning purposes but the SEBAL approach is potentially more useful for management in that it establishes the amount of water being used by the crop and can help identify where water is being wasted.     

Remote sensing analysis of the land surface temperature anomaly in the sand-dune region across the Israel-Egypt border

In the sand-dune region across the Israel-Egypt border, an anomalous phenomenon of thermal variation was observed on remote sensing images: the Israeli side with much more vegetation cover has higher surface temperature than the Egyptian side, where bare sand surface prevails. The study intends to examine the phenomenon using NOAA-AVHRR and Landsat TM data. The focus is to analyse the seasonal and spatial change of land surface temperature (LST) in the border region, to verify it through ground truth measurements and to simulate the average LST change on both sides according to surface composition structure. A split window algorithm containing only two parameters (transmittance and emissivity) has been developed for retrieving LST from NOAA-AVHRR data and a mono-window algorithm is proposed for computing LST from the only one thermal band of Landsat TM data. Application of these algorithms to the available AVHRR and Landsat TM data indicates that the LST anomaly does occur not only in one day but almost all the year. In hot dry summer the Israeli side is usually about 2.5-3.5°C hotter. In wet cool winter the LST difference between the sides is not large but the Israeli side still has higher LST. The Egyptian side may have slightly higher LST when surface temperature is below 20°C, several days after heavy rain, which leads to very wet surface conditions. The sharp LST contrast disappears on night-time images. Ground truth measurements indicate that the LST contrast mainly can be attributed to the surface temperature difference on the two typical surface patterns: biogenic crust and bare sand, which have above 3°C difference in surface temperature during summer. Experiments on soil samples from the field indicate that biogenic crust and sand have emissivity values of about 0.972 and 0.954, respectively, in hot dry conditions that match the environment of the region in summer. Surface composition determination based on three methods indicates that more than 72% of the ground on the Israeli side is covered with biogenic crust and more than 80% on the Egyptian side is bare sand. Actually, the LST anomaly can be understood as the direct result of surface composition difference, especially in biogenic crust and sand cover rate. Simulation with this surface composition difference shows that the Israeli side has steadily higher LST when the temperature of the biogenic crust is more than 1°C higher that of the sand surface, which usually occurs at moderate to high temperature levels (>30°C). When temperature is between 15 and 25°C, such as at about midnight, the two sides will have no obvious LST difference. This result is in agreement with the remote sensing observation. Therefore, it can be concluded that the vegetation cover does not contribute much to the LST contrast in comparison to the effect of the biogenic crust and sand cover.     

Use of low cost Landsat ETM+ to spot burnt villages in Darfur,Sudan

A change detection analysis of Landsat ETM+ data from the conflict‐affected area of Darfur Province in Sudan demonstrates that the recent (2003–2004) widespread burning of villages can be mapped with high accuracy (98.5% producer accuracy) at a much lower cost than other methods. By comparing albedo from two images with a 1 year interval, it was found that approximately half of the 352 survey villages had a decreased reflection pattern that could be linked to being burnt. The analysis found albedo more stable as a burnt village indicator than the use of Landsat bands 4 and 7 and the normalized burn ratio. The method is very cost effective and permits the large scale monitoring of certain types of human rights abuse, such as scorched‐earth tactics.     

Remote sensing and GIS for locating favourable zones of lead-zinc-copper mineralization in Rajpura-Dariba area,Rajasthan, India

This paper reports the results of a pilot study carried out in RajpuraDariba area, Rajasthan, for locating favourable zones of lead-zinc-copper (Pb-Zn-Cu) mineralization using remote sensing, Geographical Information System (GIS) and geostatistical modelling techniques. Remotely sensed data, both aerial and satellite, were used to update the existing geological map. ATLAS GIS software and multivariate geostatistical techniques were used to analyse and integrate different types of geological and geophysical datasets. The Favourability Index (FI) maps prepared during this study show the occurrence of three favourable zones for Pb-Zn-Cu mineralization. They are: (i) around and north of Rawan ka Khera; (ii) isolated spots between Ruppura and Bhupalsagar; and (iii) north of Dhani. Selective geochemical sampling and resistivity profiling carried out in these favourable zones indicated the presence of geochemical anomalies (anomalous concentrations of Zn and Cu) and low/moderate resistivity zones, respectively. Recent drilling carried out by the Department of Mines and Geology (DMG), Rajasthan, at about 2.5 km north of Rawan ka Khera (one of the predicted favourable zones) indicated evidence of Cu mineralization at a depth of about 70 m.     

Remote sensing of aerosols over the oceans using AVHRR data Theory,practice and applications

Abstract

The basic features of single- and dual-channel aerosol retrieval algorithms based on matching radiances measured in AVHRR channels -1 (～0.58-0.68 μm) and -2( ～0.73-1.10μm) with model computations will be described. The use of the NOAA/NESDIS single-channel algorithm will be illustrated with examples of detection and mapping of enhanced atmospheric turbidity over the oceans. The effects of variations in the physical and radiative properties of atmospheric aerosols, and in atmospheric ozone and water vapour, will be briefly discussed in the light of model sensitivity analyses.     

Remote sensing of solar-induced chlorophyll fluorescence: Review of methods and applications

Interest in remote sensing (RS) of solar-induced chlorophyll fluorescence (F) by terrestrial vegetation is motivated by the link of F to photosynthetic efficiency which could be exploited for large scale monitoring of plant status and functioning. Today, passive RS of F is feasible with different prototypes and commercial ground-based, airborne, and even spaceborne instruments under certain conditions. This interest is generating an increasing number of research projects linking F and RS, such as the development of new F remote retrieval techniques, the understanding of the link between the F signal and vegetation physiology and the feasibility of a satellite mission specifically designed for F monitoring. This paper reviews the main issues to be addressed for estimating F from RS observations. Scattered information about F estimation exists in the literature. Here, more than 40 scientific papers dealing with F estimation are reviewed and major differences are found in approaches, instruments and experimental setups. Different approaches are grouped into major categories according to RS data requirements (i.e. radiance or reflectance, multispectral or hyperspectral) and techniques used to extract F from the remote signal. Theoretical assumptions, advantages and drawbacks of each method are outlined and provide perspectives for future research. Finally, applications of the measured F signal at the three scales of observation (ground, aircraft and satellite) are presented and discussed to provide the state of the art in F estimation.     

Remote sensing and GIS for detecting changes in the aquatic vegetation of a rehabilitated lake

Remote sensing and geographical information system (GIS) methods combined with ground estimations were used to assess the effects of rehabilitation on the aquatic vegetation of a shallow, eutrophic lake in Finland. Aerial photograph interpretation was used to study the distribution of aquatic vegetation before (1953, 1996) and after (2001) rehabilitation in 1997. A digital elevation model was derived to relate the change in the aquatic vegetation to water depth. In addition, changes in the biomass of the most abundant species of the lake, Common Club-rush (Schoenoplectus lacustris), were studied by means of a regression analysis relating the ground estimations to the reflectance values (R ²=0.889, p@lt;0.001). The results indicated that the objective of the rehabilitation--to stop the overgrowth process--has at least temporarily been achieved. After rehabilitation the most noticeable change had taken place in the area covered by floating-leaved vegetation. Greater proportional changes in the aquatic vegetation areas had occurred in the deep rather than in the shallow areas. A decrease in biomass of Common Club-rush was estimated to be 30% due to rehabilitation. The use of remote sensing and GIS provided valuable information on temporal and spatial changes in the aquatic vegetation, and the methods could be applied more extensively for lake monitoring purposes.     

Remote sensing and GIS techniques for the study of springs in a watershed in Garhwal in the Himalayas,India

Water has been described as the elixir of life, the source of energy that sustains life on Earth and the factor that governs the evolution and the functioning of the universe. Increased use of water in the face of the impairment of the natural environment and ecology and the drying up of springs and reduction in their discharge and those of streams in the Lesser and Outer Himalayas are the most serious problems calling for study and exploration of groundwater resources in the Himalayan region. The hilly regions of India are facing a serious water availability crisis, particularly during summer months. Viable sources of water, such as springs in the Himalayas, which are plentiful in the hills, are drying up due to rapid and unplanned developments. The present study deals with the delineation of springs in the Chandrabhaga watershed using remote sensing and GIS technologies. The study demonstrates that the coincidence of lineaments, derived from merged satellite data, and the drainage density show good correlation with the present spring locations in the Chandrabhaga watershed. The study shows also that the locations of various springs have changed since 1981, perhaps due to rapid changes in the landuse pattern in the watershed between 1981 and 1997. Besides landuse, topography, geology and geological structures are among the most influential factors affecting spring location and discharge. An integrated approach of remote sensing and GIS is proved to be an efficacious technique for the study of springs in a mountainous watershed.     

Remote sensing of vegetation principles,techniques, and applications,edited by Hamlyn G. Jones and Robin A. Vaughn

In South African grasslands, rangeland management is strongly related to land tenure. Communal farms are reported to exhibit less desirable vegetation conditions for livestock than commercial farms. Time series of high spatial and temporal resolution imagery may be useful for improved evaluation of these rangelands as they provide information at a spatial scale similar to the typical scale of field assessments and may thus overcome the limited spatio-temporal representativeness of field measurements. A time series of 13 RapidEye images over one growing season (2010–2011) was used to explore spectral differences between and within two management systems (commercial vs. communal). Isomap ordination was applied to map continuous spectral dissimilarities of sample plots. Using regression with simultaneous autoregressive models (SAR), dissimilarities were subsequently related to ecological variables of plant and soil, including indicators for grazing effects. The largest differences were found between sample plots of communal and commercial farms. Vegetation attributes were significantly related to dissimilarities in reflectance, both from the growing season and the dormant period. However, these relationships did not suggest vegetation degradation on communal farms. They further suggest that a management-related pattern of grazing disturbance in the summer months led to spectral differences between farms but could have impaired the detailed characterization of spectral dissimilarities related to differences in vegetation composition.     

Remote sensing of bare surface soil moisture using EMAC/ESAR data

In this paper we present first results of bare surface soil moisture retrieval using data from the European Multisensor Airborne Campaign/ Experimental Synthetic Aperture Radar (EMAC/ESAR) collected on 9 April 1994 in the Zwalm catchment, Belgium. Data from EMAC Reflective Optics System Imaging Spectrometer (ROSIS) collected on 12 July 1994 over the same catchment were used to develop land use maps. Concurrent to the EMAC/ESAR overflights field data were collected in two subcatchments of the Zwalm catchment. The paper first presents the data processing procedures used for the radar images. Then we apply a theoretical backscattering model to investigate the sensitivity of EMAC/ESAR backscattering coefficients to surface parameters (topography, surface roughness, vegetation and soil moisture). By comparing the predicted backscattering coefficients to the observed ones, we can conclude that classical measurement techniques for surface roughness parameters in remote sensing campaigns are not accurate enough for retrieving soil moisture using theoretical models. A method based on simultaneous retrieval of surface roughness parameters and soil moisture using multiple ESAR measurements is hence proposed. Promising results for retrieved soil moisture confirm the validity of the proposed method.     

Remote sensing of coastlines: detection,extraction and monitoring

This paper reviews the current status of the use of remote sensing for the detection, extraction and monitoring of coastlines. The review takes the US system as an example. However, the issues at hand can be applied to any other part of the world. Visual interpretation of airborne remote sensing data is still widely and popularly used for coastal delineation. However, a variety of remote sensing data and techniques are available to detect, extract and monitor the coastline. The developed techniques have reached a level of maturity such that they are applied in operational settings.     

Stratification of forest density and its validation by NDVI analysis in a part of western Himalaya,India using Remote sensing and GIS techniques

This study deals with the assessment of the status of forest density in the Kangra district of Himachal Pradesh, western Himalaya. A classified forest map of the area with an accuracy of 88.17% was produced using the hybrid classification method in Erdas Imagine. An IRS 1D LISS III satellite image was used for mapping and classification. Forest density was calculated in the ArcGIS environment by overlaying a mesh of uniform resolution cells (500 m×500 m) on a classified forest map. The forest density value of each cell was later used for the preparation of forest density contours. The forest density output was verified by Normalized Difference Vegetation Index (NDVI) analyses. The forest cover of the study area was found to be 34.3%. Baroh area had the highest (45.87%) forest density and Baijnath (18.65%) the lowest. Central and western regions of the district showed high‐value forest density contours (>50%). The derived NDVI values were compared against the forest density classes for assessing the accuracy of the results obtained. A positive correlation (r = 0.99) between NDVI values and forest density confirms the accuracy of the results.