ISSN:0143-1161    

DOI:10.1080/01431169008955067

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Sea surface temperatures (SSTs) in Antarctic polynias are observed with NOAA-7 imagery. The study demonstrates the possibility of separating open water areas from clouds and ice with Advanced Very High Resolution Radiometer (AVHRR) channels 1, 3, 4 and 5 accurately enough for surface-temperature retrievals. Measurements from subsequent overpasses at different viewing angles agree with each other within the theoretically derived error bounds of 0.5 to 1 deg K. It is shown that even the cold Antarctic atmosphere requires a correction to the 11 μm satellite measurements to obtain adequate SST measurements.

ISSN:0143-1161    

DOI:10.1080/01431169008955068

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

A numerical simulation of a two-flow reflectance equation was used to fit aircraft radiance data taken from a high turbidity macrotidal region. The coefficients of the model were fitted on a trial-and-error basis but with reference to known physical conditions. Both a concentration and a wavelength dependence of the optical coefficients were necessary in order to produce the final scattering to absorption ratios. The simulation study also indicated that the maximum upwell-ing wavelength could be a pertinent parameter in helping to identify water masses. The simulated remote sensing algorithms worked equally well with both the Landsat MSS data and with Nimbus-7 CZCS data, the latter taken from two regions, the Bay of Fundy and the Beaufort Sea. The comparative analysis between image ground truthing and model predictions encountered three major limitations: (1) uncertainty in the atmospheric conditions and hence correction routines, (2) the influence of highly absorbing dissolved material associated with river runoff, and (3) the exact spectral shape for broad wavebands. Within these limitations the functional form of the remote sensing algorithms were similar to those suggested by Holyer, but also incorporated ratios of wavebands. Finally, the numerical simulations were used to predictin situsediment algorithms for current and future multispectral sensors onboard Landsat-4, and -5 (MSS and Thematic Mapper), SPOT and MOSS satellite systems.

ISSN:0143-1161    

DOI:10.1080/01431169008955069

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The importance of remote sensing for monitoring the marine environment is stressed. Model calculations predict the utility of the NOAA Advanced Very High Resolution Radiometer (AVHRR) for the synoptic assessment of the sea surface temperature (SST) and the total suspended matter concentration (TSM) over large areas of the North Sea. Data processing, algorithm development and image interpretation are described. Applications for ecological and pollution transport modelling are indicated.

ISSN:0143-1161    

DOI:10.1080/01431169008955070

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Water volume reflectance images of three water cooling reservoirs were derived from airborne Daedalus DS-1260 multispectral scanner (MSS) data using a radiative transfer model to eliminate atmospheric effects and to derive downwell-ing irradiances. Sixtyin situwater volume reflectances and the associated sensor and sun geometries were input into the radiative transfer model. Using the radiative transfer model to generate water volume reflectance values at each field site, an optimization procedure minimized the difference between modelled andin situwater volume reflectances resulting in optimized sensor brightness value to radiance conversion gain and bias factors, and optimized surface visual range and mean terrain background reflectance. Subsequently water volume reflectance images were derived at six wavelengths encompassing the blue to near-infrared using the optimized atmospheric parameters and conversion factors as inputs into the radiative transfer model. Modelled reflectance images were evaluated for accuracy by statistical comparison to the in situ reflectances, and for improved contrast by subjective comparison to the original images. Daedalus DS-1260 MSS bands 3, 4, 5, 7 and 8 modelled reflectances explained 19, 78, 86, 89 and 82 per cent, respectively of thein situreflectance variances, while band 2 correlation was not significant (p<0.05). All generated reflectance image histograms showed dramatic improvement in contrast when compared with the histograms depicting variance within the original images.

ISSN:0143-1161    

DOI:10.1080/01431169008955071

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Variability of the Columbia River plume in coastal waters off the northwestern United States, 1979-1985, was observed in sea surface temperature and phytopiankton pigment images derived from Advanced Very High Resolution Radiometer and Coastal Zone Colour Scanner data. The orientation, shape, intensity and relative temperature of the plume vary in response to coastal winds and wind-driven surface currents. From October to April, plume water is oriented northward along the coast. Following the spring transition in April or May, the plume is oriented southward, either adjacent to the coast or offshore. Transition between the winter and summer forms can be observed in the satellite imagery. Brief reversals of the prevailing seasonal winds cause rapid changes in the orientation and shape of the plume. Remote sensing of the Columbia River plume offers valuable information for oceanographic studies and fisheries management in the region. Derivation of an appropriate visible-infrared signature for plume waters and tracking of tidal pulses in the plume is suggested as a promising direction for future research.

ISSN:0143-1161    

DOI:10.1080/01431169008955072

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

For multispectral analysis of forest land in mountainous areas, the estimation of true reflectance without the terrain having an effect on the sensor response is indispensable. To study this subject, the authors carried out the following experiment. First, we made a precise digital terrain model (DTM) at an interval of 10 m for a test forest site covered with Lambertian-type crown surface. Analysing the forest land from the SPOT data with the precise DTM, we obtained a classification result of forest type about 20 per cent higher accuracy than the result without application of this method.

ISSN:0143-1161    

DOI:10.1080/01431169008955073

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The bidirectional reflectance patterns of a complete (dense) canopy are examined as functions of canopy architecture, as specified by azimuth angle δeand zenith angle ψ for a leaf normal. The leaves are assumed to be opaque Lambertian reflectors, all with identical orientation and reflectance properties throughout the canopy, and randomly distributed with respect to the irradiation field and the viewing direction. Multiple reflections are not considered and irradiation is by direct beam only. Simple analytical expressions for the bidirectional reflectance factor are presented and analysed. The nadir reflectance (expressed as a fraction of the leaf reflectance) for canopies whose leaves face the sun, δe= 0, is bounded by cos ψ and 1/2; cos ψ. The nadir reflectance initially increases with increasing ψ, but then decreases when ψ reaches moderate to large values. For a δe= π canopy, on the other hand, the much lower nadir reflectance is bounded by ½ cos ψ and 0, and decreases with increasing ψ throughout the entire range of ψ (0 to ½π). The maximum bidirectional reflectance occurs at large viewing zenith angles (i.e. close to the horizon). The maximum reflectance is always higher for a δe= 0 canopy than for a δe= π canopy, but the differences become small when ψ approaches ½π. The bidirectional reflectance thus depends on the leaf azimuth as well as the zenith angle. Leaf-area azimuthal distributions should be considered when conducting model inversions to infer canopy characteristics and architecture.

ISSN:0143-1161    

DOI:10.1080/01431169008955074

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Sodar (sound radar) echograms recorded at the Indian Statistical Institute, Calcutta, often exhibit stratified or elevated layers over the ground-based inversion. These have been noticed often after the occurrences of thunderstorms and rain. These layers may be single or multiple, continuous or intermittent and are associated with some perturbations even as gravity wavelike structures. All these features of the lower atmospheric structures over this coastal station, as detected by a sound radar, are discussed in this paper.

ISSN:0143-1161    

DOI:10.1080/01431169008955075

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

A polytetrafluoroethylene (PTFE ‘Halon’) coating is described for the manufacture of reference reflection panels for field radiometry. Data are given for the spectral and Lambertian properties of the surface of these panels compared with others with coatings of barium sulphate or pressed Halon.

ISSN:0143-1161    

DOI:10.1080/01431169008955076

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor