ISSN:0143-1161    

DOI:10.1080/01431169508954426

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

NOAA AVHRR thermal infrared images, meteorological measurements and model calculations have been used to estimate the magnitude of the processes controlling the sea surface temperature variability in the Bay of Biscay. The estimates are based on the equation of temperature conservation and the equation for the total derivative. The results show that local time change, advection, horizontal diffusion and vertical turbulent flux vary with time and space. The sea surface temperature variability is mainly controlled by vertical turbulent flux and advection. For an average of five-day estimates, the order of the relative importance of the processes is vertical turbulence (38 per cent), advection (32 per cent), local time change (22 per cent) and horizontal diffusion (8 per cent).

ISSN:0143-1161    

DOI:10.1080/01431169508954427

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Since February 1989 measurements from MOS-1 could be received at Syowa Station in Antarctica. The first set of MOS-1 visible and thermal infrared (VTIR) recordings from Syowa Station is analysed in this study. A method developed by Schüssel and Grassl is applied for ice and cloud filtering. For clear ocean pixels the sea surface temperatures are estimated by applying Muneyama's split window algorithm. A sea surface temperature composite of ten VTIR passes is presented.

ISSN:0143-1161    

DOI:10.1080/01431169508954428

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

This paper presents the most suitable image processing techniques being used at present for recognising features either lying on the seafloor or floating in the water column. The preprocessing methodology is already incorporated in the sonar system, and as we cannot access the raw data, it is not included in this paper. The studied images correspond to the Cabrera Archipelago, in the Mediterranean Sea.

ISSN:0143-1161    

DOI:10.1080/01431169508954429

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The change in cropping pattern between rabi 1990-91 and kharif 1991-92 crop seasons is studied for 36 distributary command of Tungabhadra left-bank main canal. Indian Remote Sensing Satellite (IRS)-LISS 2 data of 25 February 1991 (rabi) and 2 October 1991 (kharif) are subjected to change detection analysis by developing suitable image differencing algorithm. On the differenced image no change areas of same crop or fallow and change areas of one crop to other crop, fallow to crop or crop to fallow are identified by selecting appropriate threshold values. The results show that though there is marginal increase in the cropped area, the cropping pattern is almost similar.

ISSN:0143-1161    

DOI:10.1080/01431169508954430

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A detailed laboratory experiment was conducted on three soils of different textures viz., sand, sandy clay loam and clay to study the influence of soil salinity and sodicity on the complex dielectric behaviour of soils as a function of volumetric soil moisture using an L-band (1 ·25 GHz) dielectric probe. The results revealed that soil salinity has no influence on the real part of the dielectric constant (ϵ') whereas, the imaginary part (ϵ'') is dependent and increases with increase in salinity for all the soils considered. It was found that the real part is more dependent on soil moisture and imaginary part on soil salinity. The sodicity of a soil has no influence either on real part or imaginary part. This study shows L-band (1·25 GHz) microwave response to soil salinity. It also demonstrates the possibility of separating saline soils from sodic soils at L-band frequencies under moist soil conditions.

ISSN:0143-1161    

DOI:10.1080/01431169508954431

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

AVHRR data are widely used to monitor vegetation greenness and to provide a gross measure of primary production throughout the world. This paper examines whether AVHRR data can be used for determining the extent of land degradation in arid rangelands under commercial grazing using models of vegetation dynamics and animal grazing behaviour developed for Landsat-MSS data. These models are applied after large rainfall events and either search for systematic change in average vegetation cover across relatively uniform landscapes with increasing distance from stock watering points or examine the magnitude of vegetation response to rainfall for each pixel.

ISSN:0143-1161    

DOI:10.1080/01431169508954432

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

In recent years significant effort has gone into collecting, processing, and analysing normalized difference vegetation index (NDVI) data derived from the National Oceanic and Atmospheric Administration's (NOAA) 1-km advanced very high resolution radiometer (AVHRR) for environmental applications. The ISODATA clustering procedure has been employed using time-series AVHRR maximum NDVI composites to produce a land cover characteristics data base. This study examines the sensitivity of the ISODATA clustering results to changes in sampling procedures and processing parameters when applied to NOAA NDVI time-series data. The effects of varying the sampling strategy, sampling intensity, clustering parameters, and number of iterations have been evaluated. The ISODATA clustering procedure was most sensitive to variations in sampling intensity and clustering parameters.

ISSN:0143-1161    

DOI:10.1080/01431169508954433

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Eight and a half years (January 1979 to August 1987) of Scanning Multichannel Microwave Radiometer (SMMR) data taken at a frequency of 6·6 GHz for both day and night observations at both polarizations were processed, documented and used to study the relationship between brightness temperature (TB) and antecedent precipitation index (API) in a wide range of vegetation index (normalized difference vegetation index (NDVI) varies from 0·2 to 0·6) in the mid-west and southern United States. In general, this study validates the model structure for soil wetness developed by Choudhury and Golus. For NDVI greater than 0·45 the resultant microwave signal is substantially affected by the vegetation. The night-time observations by both polarizations gave a better correlation between TBand API. The horizontal polarization is more sensitive to vegetation. For the least and greatest vegetated areas, nighttime observations by vertical polarization showed less scatter in the TBversus API relation. A non-linear model was developed for soil wetness using horizontal and vertical plarization and their difference. The estimate of error for this model is better than previous models, and can be used to obtain six levels of soil moisture.

ISSN:0143-1161    

DOI:10.1080/01431169508954434

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The directional spectral reflectance of deciduous forests changes markedly throughout the year as a consequence of the phenology of the canopy and understorey and changes in the spatial arrangement and density of scene components. This paper presents the results of a 1-year experiment using a tower-mounted spectroradiometer to measure the seasonal changes in the nadir reflectance properties of ash and beech canopies. Seasonal variations in reflectance in red wavelengths were found to be inversely related to percentage cover, whilst variations in near-infrared reflectance were directly related to percentage cover although for both wavelength regions changes in reflectance were not always exactly synchronous with changes in percentage cover. A strong rectilinear relation was observed between NDVI and percentage cover when data from both species were combined. The shape of the seasonal NDVI profile revealed differences between the two species that was ascribed to phenological differences between ash and beech canopies. The position of the wavelength of maximum slope in the region 680-750 nm, was found to shift between two domains depending on the particular association of scene elements presented to the sensor as canopy cover changed.

ISSN:0143-1161    

DOI:10.1080/01431169508954435

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor