ISSN:0143-1161    

DOI:10.1080/01431168608954713

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Through an extensive literature review the results of previous lidar investigations in Australia, Canada, Sweden, the U.S.A. and West Germany have been evaluated. Based on these findings estimates are given for the anticipated depth capability, measurement accuracy and operational constraints for a laser system in U.K. waters. Consideration is also given to the possibility of deploying a depth-sounding lidar for non-bathymetric purposes such as depth-resolved turbidity mapping.

ISSN:0143-1161    

DOI:10.1080/01431168608954714

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

A semianalytic Monte Carlo radiative transfer model (SALMON) is employed to probe the effects of multiple-scattering events on the time- and depth-resolved lidar signals from homogeneous aqueous media. The effective total attenuation coefficients in the single-scattering approximation are determined as functions of dimensionless parameters characterizing the lidar system and the medium. Results show that single-scattering events dominate when these parameters are close to their lower bounds and that when their values exceed unity multiple-scattering events dominate.

ISSN:0143-1161    

DOI:10.1080/01431168608954715

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Whitecap coverage (W), which influences the apparent microwave brightness temperature and short-wave albedo of the sea surface, is not only a strongly non-linear function of the l0m-elevation wind speed (U), but also varies with changes in the stability of the lower atmosphere (i.e. with alterations in the water-air temperature difference AT), and with changes in the surface-sea water temperature (Tw). Thus wind retrieval algorithms to be applied to open ocean data from whitecap-detecting satellite instruments should ideally be of the form, U(W, δT, Tw, d), where d is a measure of the effective wind duration. The wind speed associated with the onset of whitecapping, while also varying with AT and Tw, is typically 3 to 3-5ms-1, not the often quoted 7ms-1

ISSN:0143-1161    

DOI:10.1080/01431168608954716

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

An algorithm for the retrieval of the sediment content of turbid coastal waters from Coastal Zone Colour Scanner (CZCS) data has been developed theoretically and tested against experimental values. The theoretical approach consisted of numerical simulations and sensitivity analyses, focused on the search for a retrieval variable with low sensitivity to chlorophyll-like pigments, and to uncertainties in the procedure for the determination of the atmospheric correction applied to the remotely measured radiances. The variableX, = [R(550) - R(670)]° [R{520)/R(550)]6where R(λ) is the subsurface irradiance reflectance at wavelength X, has been found to meet the above requirements, provided 0–5asλ 1·5 and – 2·5≤b≤–0·7. The algorithm log(sed.) = A + Blog(Ars) has been applied to the analysis of a set of CZCS scenes of the Adriatic Sea, with sediment and chlorophyll concentration ranges from 1 to 13gm-3 and from 0–1 to l–5mgm~3, respectively. The theoretically predicted low sensitivity to the atmospheric correction method has been confirmed by the experimental evidence, suggesting the possibility of using a simplified correction procedure, even in turbid waters where sediment and chlorophyll contents are uncorrelated. The experimental exercise led to the identification of two water types in the northern basin of the Adriatic Sea, characterized by a substantially different correlation between sediment and chlorophyll, and corresponding to coastal zones with different hydrological conditions

ISSN:0143-1161    

DOI:10.1080/01431168608954717

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Radiance measurements using a hand-held radiometer configured to match LANDSAT TM bands 3–5 were compiled from Spartina anglica plots in five geographically separate marshes in Brittany, France. Aboveground biomass of the plots was harvested following the determination of radiance. Simple regression models employing a vegetation index to predict S. anglica leaf, live and total aboveground biomass from spectral radiance values were derived from data collected in one of the marshes. Radiance measurements gathered in the other four marshes (test marshes) were substituted into the biomass estimation models. In three of the test marshes, the mean model-predicted leaf and live biomass were within 1–13 per cent of the harvest values. In the other test marsh, dead material located near the top of the canopy caused biomass to be underestimated. Total (live and dead) biomass predictions were not close to harvest values in any of the marshes. This study demonstrated that a simple regression equation relating radiance data (in the form of a vegetation index) to S. anglica biomass in one marsh can be employed to accurately predict leaf and live S. anglica biomass in other, distant, marshes.

ISSN:0143-1161    

DOI:10.1080/01431168608954718

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

A canopy-reflectance (CR) model for row-planted vegetation is presented. Its use for an estimation of important biophysical variables like leaf-area index (LAI) and average leaf angle (ALA) from bidirectional CR data is discussed. Using field-measured CR data for a partially covered soybean canopy, it is shown that one can accurately estimate LAI, ALA and extent of percentage of ground cover from CR data. Row canopy reflectance

ISSN:0143-1161    

DOI:10.1080/01431168608954719

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The Earth's forests fix carbon from the atmosphere during photosynthesis. Scientists are concerned that massive forest removals may promote an increase in atmospheric carbon dioxide, with possible global warming and related environmental effects. Space-based remote sensing may enable the production of accurate world forest maps needed to examine this concern objectively. To test the limits of remote sensing for large-area forest mapping, we use LANDSAT data acquired over a site in the forested mountains of southern California to examine the relative capacities of a variety of popular image processing algorithms to discriminate different forest types. Results indicate that certain algorithms are best suited to forest classification. Differences in performance between the algorithms tested appear related to variations in their sensitivities to spectral variations caused by background reflectance, differential illumination, and spatial pattern by species. Results emphasize the complexity between the land-cover regime, remotely sensed data and the algorithms used to process these data.

ISSN:0143-1161    

DOI:10.1080/01431168608954720

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Antarctic research is often difficult to conduct because of the harsh environment, large extent of the continent and remoteness of many areas of interest. Satellite remote sensing is being investigated as a tool for aiding research throughout Antarctica. One application is the detection of katabatic winds and their temperature structure. Presented here is a katabatic event that occurred in July 1984 and was detected in the NOAA-7 polar orbiter thermal data. The study area is over the Transantarctic Mountains and Ross Ice Shelf. Results of the research and image processing analysis done for this case are provided. Intial results show that the satellite data can supply much information about the temperature change that occurs during this adiabatic process. Temperature increases were found to range from 20 to 30 deg k higher than the surrounding area temperatures for Byrd and Skelton glaciers. This was verified from ground information, collected by automatic weather stations, throughout the Ross Ice Shelf and east Antarctica.

ISSN:0143-1161    

DOI:10.1080/01431168608954721

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

ISSN:0143-1161    

DOI:10.1080/01431168608954723

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor