ISSN:0143-1161    

DOI:10.1080/01431169608949169

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The results of a remote sensing study have been correlated with previous research on estuarine mixing processes and with ground sampling investigations to appraise the dispersal of effluent in the Tay estuary. The advantages of using remote sensing techniques to study the distribution of convergent fronts and their effect on the dispersal of effluent are demonstrated. The application of remote sensing data in the study of the near-shore dispersion from outfalls and the short-term dispersal behaviour of outfalls are discussed with reference to two particular sewer outfalls. The results of the remote sensing studies correlate highly with ground studies of the same areas. A modified simulation model of the flushing capacity of the Tay estuary has been developed incorporating the results of the remote sensing study. The results of the model are very similar to those calculated from a physical model. The preliminary results of a study to integrate urban hydrological and outfall dispersal models with remote sensing data are reviewed.

ISSN:0143-1161    

DOI:10.1080/01431169608949170

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Alias effect in satellite altimetry has been a topic of active research in recent years, as a result of a growing recognition of its remarkable potential consequences. So far, alias problems have been addressed in both time and space domains, but in the latter case only on the horizontal scales. In this study, we examine the impacts of alias effect on the amplitude of sea surface height measurements, which were previously of little concern. Three statistics are proposed to diagnose the resolvable amplitude or energy with respect to the original period, initial phase and data duration in the context of aliasing. The results obtained show clear evidence to support the argument that alias effect on amplitude is a common feature in altimeter sea surface height measurements, and is as important as other alias consequences.

ISSN:0143-1161    

DOI:10.1080/01431169608949171

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A mathematical model that allows simulations of the image of waves in ship wakes by either regular or interferometric airborne Synthetic Aperture Radar (SAR or INSAR) is described. The three-component velocity field induced at the ocean surface by a moving ship serves as the input to the model. The simulations take into account the effect of temporal variations of the wave field in the wake on the INSAR imaging by the velocity bunching mechanism. The model also accounts for the scanning distortion of the image. The developed algorithm allows study of the visibility of the ship wave wake by a regular SAR or by INSAR for arbitrary imaging parameters, as well as for different ship sizes and ship velocity vectors relative to the platform flight track. Various patterns of ship wake images obtained by numerical simulations are presented.

ISSN:0143-1161    

DOI:10.1080/01431169608949172

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

There is an increasing demand for development of new recreation areas and more intensive management of existing areas. With an eye to the design and implementation of comprehensive zoning plans, satellite remote sensing should provide an ideal tool for terrain analysis, vegetation, and cover type mapping, which are vital to intensive recreation planning. The study undertaken was aimed at examining the applicability of satellite remote sensing for providing necessary information to be used in forest recreation planning. A Landsat TM scene (path row 128/ 56) taken on 30 January 1992 was processed digitally on a Meridian PC image processing system by selecting a representative subsection of the scene that covered the study area. Existing land use, topographical maps, and other related ground information as well as contrast stretching and a maximum likelihood classifier ( MLC) technique were used to assist in the classification. The selection of potential recreation sites was based from potential surface analysis ( PSA ). The results showed that most of the undeveloped forest area located in the north-eastern part of Langkawi Island, Malaysia, was the most potential sites for recreational development, while the moderate recreation potential zones lay on the western part of the island. The mean overall classification accuracy obtained was 82% Therefore the study implies that it is possible to select potential recreation sites ranging from most potential to least potential in Langkawi Island using Landsat TM.

ISSN:0143-1161    

DOI:10.1080/01431169608949173

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The aim of this study is to test the feasibility of the detection and mapping of annual clearcuts from Landsat Thematic Mapper data over the forested region les Landes, in the south-west of France ( about 1 million hectares covered by uniform age monospecific forest stands of maritime pine) Two Landsat TM images acquired in summer 1985 and 1986 were used. The radiometric changes following a clearcut are analysed and compared to the changes following up other types of evolution, on a test area representing 200000ha. Newly clear felled stands showed strong increase in their mean radiometric level in the visible as well as in the middle infrared, but no clear variation in the near-infrared was found. Results of supervised image classifications using three different band combinations were compared to evaluate the potential contribution of the nearinfrared combined with the middle infrared for the detection of annual clear fellings. The following multi-temporal combinations were used: (TM–5–85, TM5– 86), (TM–5–85, TM–5–86, TM–4–86), (TM–5–85, TM–4–85, TM–5–86, TM–4–86). The combinations using the middle infrared alone led to the best identification of new clearcuts harvested between 1985 and 1986, but the commissionerror was high (about 25 per cent). The main confusion was observed on old clearcuts which were reforested between 1985 and 1986. In order to propose a global method for mapping and estimating the annual clearcuts over the whole Landes region, it is necessary to test whether the results are reproducible when images acquired at very different dates are used. Moreover, the cartographic accuracy must be controlled and improved. Effects of thinnings, which are not studied here, must also be taken into account. Then, we can propose a global system for monitoring regional forest resources.

ISSN:0143-1161    

DOI:10.1080/01431169608949174

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Data acquired during the Mac-Europe 91 campaign over the Black Forest ( Germany) are used to study the synergy of optical imaging spectrometer data ( AVIRIS) and polarimetric microwave data ( AIRSAR) for forest resource assessment. Original and new derived bands from AIRSAR and AVIRIS data are used to predict age and biomass. The best predictors ( bands) are selected through a multivariate stepwise regression analysis of each of the datasets separately. Then the joint AIRSAR-AVIRIS dataset is analysed. This study shows how the synergistic use of AIRSAR and AVIRIS data improves significantly the predictions obtained from the individual datasets for both age and biomass over the test site. In the analysis of AVIRIS data a new approach for processing large datasets as those provided by imaging spectrometers is presented, so that maximum likelihood classification of these datasets becomes feasible.

ISSN:0143-1161    

DOI:10.1080/01431169608949175

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The agricultural land cover in a 263 km2 irrigation district was classified utilizing two Landsat 5 TM scenes. Manual and automatic selection of training areas for the classification of two single subscenes and a combined multitemporal subscene result in several differently classified images. The extent of each land cover class was first estimated by area frame sampling and further expansion of the ground data to the entire irrigation area. The regression of the sampled surface on the corresponding pixels in the classified images was used to improve the regression estimates of the areas of different land cover classes. To ascertain if there is any statistical difference between the relative efficiencies (RE) of the regression estimator using each one of the classifications, and being RE= 1/ (1 -r2) a test of equality between correlation coefficients was applied. When the correlation coefficients were significantly different the most precise estimation was indicated by the highest RE. Manual multitemporal classifications provided the most precise results, with the exception of the single image spring classification of rice.

ISSN:0143-1161    

DOI:10.1080/01431169608949176

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The huge sulphur dioxide and heavy metal emissions from the nickel and copper smelters in the Kola Peninsula, Russia, have caused severe vegetation damage and destruction in the surrounding areas during the past few decades. An attempt was made to detect changes in the state of the vegetation in the environs of the Monchegorsk smelters using Landsat MSS images from the years 1978, 1980, 1986, and 1989 as an input for muUitemporal image analysis. By comparing Normalized Difference Vegetation Index ( NDVI) values from different years, a clear deterioration in the proportion of green vegetation could be distinguished during the time period observed. Unsupervised classification of the images showed the same trend: the vegetation around the smelters has undergone severe degradation. A large composite image mosaic of the TM channels 6, 4 and 1 overlaid by a S02 distribution model showed clearly that severe damage area corresponds to an yearly average concentration of 40-60μ g m−3 of S02.

ISSN:0143-1161    

DOI:10.1080/01431169608949177

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A geometrical model, taking into account the diffuse, as well as the specular component of energy leaving soil surfaces in the visible and near-infrared, is discussed here. The model computes the bidirectional, reflectance of soils illuminated by a single source. A rough soil surface is simulated by equal-sized spheroids regularly spaced on a horizontal surface. The model was tested using soil bidirectional reflectance data obtained in laboratory conditions by Jacquemoud et al in 1992. Two parameters describing soil surface geometry were used for modelling the soil relalive reflectance in laboratory conditions: the relative distance (d/ a) between spheroids (relative to their horizontal radii ( a )and the shape of spheroids (b/ a) ( as proportion of their vertical (b) to horizontal radii (a)) The simulation of reflectance for soil surfaces of pebbles and sand, containing simple dense particles with rounded edges, can be carried out using the d/ a and b/ a ratios which nearly described their aclual geometry. The reflectance of more geometrically complicated soil surfaces, such as clay and peat with irregular secondary porous aggregates, can be simulated by surfaces of effective geometry of vertically elongated spheroids.

ISSN:0143-1161    

DOI:10.1080/01431169608949178

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor