ISSN:0143-1161    

DOI:10.1080/01431169508954408

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Many researchers have delimited objects' heights, mainly heights of the Earth surface for topographic mapping or digital elevation model (DEM), with SPOT-images by using stereo observe-systems. In this paper, we try to delimit buildings' heights from the shadow in a panchromatic SPOT-image. The heights of 42 buildings are calculated with this method and checked. The root-mean-square error is 3·69 m. A main inference comes from the blocked shadows.

ISSN:0143-1161    

DOI:10.1080/01431169508954409

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The inference of surface spectral reflectance using visible observations is complicated mainly because of scattering effects. In the present paper we attempt a solution to the problem of retrieval of surface reflectance from satellite radiance measurements based on a solution of the radiative transfer equation. We have developed an operational method which relies on multiple view angle observations or multiple solar zenith angle observations of the surface to accomplish part of this task in a routine manner. This approach may be used for ERS-2 ATSR visible bands because there will be two view angle observations for the same area at essentially the same time.

ISSN:0143-1161    

DOI:10.1080/01431169508954410

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

This paper presents a simple and operational thermal inertia model by using the phase angle information of the diurnal temperature change. The model which is developed in this paper is based on our first-order approximation operational thermal inertia model. We use a second-order approximation for the boundary conditions and a second-order approximation for the surface temperature series expression. The importance of this work is that from our model real thermal inertia (as distinct from apparent thermal inertia) can be computed directly. The model requires only one field measurement parameter for the calculation of real thermal inertia; this is the time of maximum temperature in the daytime and this parameter is easily obtained from a meteorological station. For the regions having vegetative cover, the thermal inertia value is the weighted thermal inertia values of vegetated cover and soil ground.

ISSN:0143-1161    

DOI:10.1080/01431169508954411

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Management systems on agricultural land in Norway are causing concern because of increasing area wide soil erosion, consequent increase in sediment loads and nutrient losses to waters, and their consequent pollution. Monitoring of areas in autumn is important because this is the start of a season when much of the erosion occurs. This is often caused by management systems in autumn, but also because climatic conditions in this season are important for erosion processes.

ISSN:0143-1161    

DOI:10.1080/01431169508954412

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The yield of grain Sorghum cultivated in dry-land regions in India fluctuates widely in relation to its critical growth phases depending on the weather conditions. Vegetation indices derived form remote sensing data acquired at the time of maximum vegetative growth are indicative of crop growth and vigour and consequent potential grain yields. In this paper we investigate rabi (winter) sorghum yields using Indian Remote Sensing Satellite's Linear Imaging and Self Scanning-I (IRS LISS-I) sensor data and monthly rainfall distribution data of the recent four seasons for the 37 tehsils (sub-units of districts) that constitute the three principal sorghum producing districts of the central Maharashtra state (India). The multiple linear regression yield models with both the spectral and spectro-meteorological parameters have been developed for tehsil, as well as the district yields, by identifying critical parameters with model estimation errors of about 22 per cent on tehsil yields and about 5 per cent on district yields. The yields are found to be correlated significantly with monsoon rainfall about 1 to 2 months before sowing. This study brings out the problems of yield modelling of the semi-arid tropical crop in a small region using remote sensing data only, and shows that the vegetation indices deduced from remote sensing data are found to be good indicators of the yield on large spatial scales, as the effects of varying rainfall on yields largely cancel out.

ISSN:0143-1161    

DOI:10.1080/01431169508954413

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The capability of airborne (AVIRIS) and laboratory spectrometry was investigated for assessing the chemical composition of foliar elements of a pine forest (The Landes, SW France). Simultaneously with AVIRIS acquisition, an atmospheric profile was carried out, and the forest vegetation was sampled for chemical analyses and laboratory spectral measurements. Predictive relations between concentrations of nitrogen (r=97 per cent), lignin (r = 89 per cent) and cellulose ( = 83 per cent) and reflectances of pre-treated pine needles were determined through stepwise regression analyses. A methodology was designed to assess their extrapolation to remotely acquired spectrometric data: (1) geometric and atmospheric corrections, (2) registration within a biophysical data base (e.g. LAI, biomass), and (3) comparative statistical analysis of laboratory and airborne spectrometric information. The application of laboratory derived relationships led to relatively large correlations for nitrogen (74 per cent) and cellulose (79 per cent); poorer results were obtained for lignin (55 per cent). The use of atmospherically corrected reflectances led to slightly worse correlations: nitrogen ( 73 per cent), cellulose (78 per cent) and lignin (44 per cent). It was attempted to improve these results while taking into account the influence of the canopy structure and total quantity of chemical compounds. (1) Slightly poorer results were obtained when chemical concentrations were weighted with local biomass and LAI values. (2) Predictive equations based on laboratory measurements were applied to reflectances of pine needles that were computed through the inversion of two reflectance models. This last approach improved correlations for lignin ( 74 per cent). No improvement was observed for nitrogen ( 70 per cent) and cellulose ( 69 per cent). Finally, in order to provide suitable information to GIS based ecosystem models chemical concentrations were tentatively mapped.

ISSN:0143-1161    

DOI:10.1080/01431169508954414

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

We validated a canopy backscatter model for loblolly pine forest stands at the Duke Forest, North Carolina, by comparing the observed and modelled SAR backscatter from the stands. Given the SAR backscatter data calibration uncertainty, the model made good predictions of C-HH, C-HV, L-HH, L-HV, L-VV, P-HH, and P-HV backscatter for most of 25 stands studied. The model overestimated C-VV backscatter for several stands, and largely overestimated P-VV backscatter for most of the stands. Using the collected SAR backscatter and ground data, and the backscatter model, we studied the influences of changes in biomass on SAR backscatter as a function of radar frequency and polarization, and evaluated the feasibility of deriving the biomass from the backscatter. This study showed that C-HH, C-HV, C-VV, L-VV, and P-VV SAR backscatter may be insensitive to the biomass change. L-HH, L-HV, P-HH, and P-HV SAR backscatter changed more than 5dB as the biomass varied. This study also showed that the L-HH and P-HH backscatter or L-HV and P-H V backscatter may be used to develop algorithms to retrieve trunk biomass or canopy biomass of the loblolly pine forests.

ISSN:0143-1161    

DOI:10.1080/01431169508954415

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

An improved direct method is presented for the calculation of fog optical depth and liquid water path from fog top albedo using AVHRR channel 1. Fog top albedo is determined by means of a simple radiative transfer model under special consideration of radiometric corrections. By the conversion of channel I digital counts into a reflectance factor, a correction has to be performed, due to the degradation of channel 1 radiometer with time. By omitting atmospheric and anisotropy corrections, modal uncertainties in the calculations of fog top albedo in the order of ±25 per cent and ± 5 per cent were obtained. Assuming a homogeneous droplet distribution within fog layers at scan lime, a horizontal visibility was calculated from fog optical depth and fog geometrical thickness, whereas fog liquid water content was derived from liquid water path and fog thickness. Ground truth from high resolution transmiss-ometer observations showed an encouraging accuracy with a mean deviation between the observed and calculated visibility of about 56 m and a mean error in the determination of fog liquid water content of about 0·025 gm−3.

ISSN:0143-1161    

DOI:10.1080/01431169508954416

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A series of 1 km Advanced Very High Resolution Radiometer (AVHRR) images for the period of 1991-1992 are used to compute the attitude variations of the NOAA-11 spacecraft using ground control points (GCPs or land surface reference points) in conjunction with a recently developed precise AVHRR image navigation software package (Rosborough et al. 1994). The images were first corrected for the NOAA satellite clock drift and then roughly 2-3 images per month were used to compute roll, pitch and yaw to match the GCPs in each image. Higher frequency satellite attitude variations were monitored using a 2 to 3 day sampling interval for two month-long periods in May 1991 and February 1992. The pitch and yaw behaviour of NOAA-11 was found to oscillate about a mean value near 0·0, with an amplitude of ±0·002 radians for pitch and ±0·001 radians for yaw. The variability in the roll axis was characterized by an amplitude of ±0·0015 radians about a mean offset of −0·002 radians. The higher frequency month-long samples showed similar behaviour in terms of amplitude and phase when compared with the annual time series. The NOAA-11 onboard attitude information was found to have a much smaller amplitude with extremely regular variability and was apparently not related to the AVHRR image derived attitude variations.

ISSN:0143-1161    

DOI:10.1080/01431169508954417

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor