摘要:

Agricultural crops and rangeland resources over above 30 million km2in some 55 Third World countries arc subject to ravages by the desert locust. Successful breeding, triggered by suitable ecological conditions when widespread rainfall results in development of vegetation in the desert-locust recession area, can produce rapid increases in desert-locust populations, resulting, if uncontrolled, in large numbers of highly mobile and devastating swarms containing billions of locusts. Satellite remote sensing offers the only possibility of monitoring the 16 million km2desert-locust recession area situated largely in remote and inaccessible deserts of northern and eastern Africa, the Near East, and south-west Asia. Use of LANDSAT and National Oceanic and Atmospheric Administration (NOAA) satellite imagery for analyses of green vegetation blooms in desert-locust breeding areas suggests an operational programme based upon the NOAA Advanced Very-High-Resolution Radiometer sensor

ISSN:0143-1161    

DOI:10.1080/01431168508948429

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

A discussion of the benefits of satellite remote sensing to urban studies is followed by a consideration of resolution requirements and associated problems. Problems include loss of contextual clues for interpretation, heterogeneity of cover surfaces, temporal differences in atmospheric effects and registration of different scenes. A number of solutions to these problems are considered, such as the use of reference surfaces for atmospheric corrections and the use of targetted control points for temporal change monitoring. The specific advantages of high-resolution satellite data are particularly considered

ISSN:0143-1161    

DOI:10.1080/01431168508948430

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Extended areas of light textured soil may deteriorate when weather and cultural practices are favourable for slaking. In 1979 newly reclaimed polder soil slaked and in 1980 was slaked artificially. The soil surface roughness, pore volume and water infiltration rate decreased with slaking, whereas soil moisture content and penetration resistance were increased. These changes in soil characteristics decreased soil surface radiant temperature by ±2degC, while differences in reflectance were small, in the afternoon of a sunny day when soil moisture content was high or medium. Slaked fields were easily detected in spring by the use of infrared line scanning, while possibilities using aerial photography were uncertain. Under dry soil conditions false colour photography may be preferred to thermal imagery. Differences early in the morning were not measurable.

ISSN:0143-1161    

DOI:10.1080/01431168508948431

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Several vegetative indices were analysed for their sensitivity and stability to green-leaf-area index (LAI) changes over various planting dates and irrigation frequencies of wheat grown at Phoenix, Arizona, from 1978 to 1980. Seasonal patterns of greenness showed that values saturated at LAI values above 4·0 did not return to the pre-emergence bare-soil value at senescence, and were not uniquely related to LAI over the various planting dates. Regressions of individual MSS band reflectances against LAI also showed that there was not a unique relation between any of the bands and LAI. However, the near-infrared/red reflectance ratio was stable over all planting dates and could be used successfully over a number of years and locations

ISSN:0143-1161    

DOI:10.1080/01431168508948432

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Spectral responses in eight wavebands (three visible, two near-IR, two mid-IR, and one thermal IR) were measured by repetitively traversing a radiometer over several rows of cotton (Gossypium hirsutumL.). After an initial measurement, the stems of one row (which had previously been tied to wooden dowels) were cut at a point just above the soil. The subsequent dessication of plants within this row was followed by comparing its reflectance and emittance with a control row. All wavebands measured reacted rapidly to stress with the visible and thermal IR showing a larger change than the near-IR. Reflectance changes caused by canopy geometry changes were apparently greater than those caused by leaf physiological and anatomical changes in all but the visible red band. The increase in red reflectance was attributed to a rapid decrease in absorptance by leaf chloroplasts. As expected, the radiometrically determined plant temperatures increased with time after the stress was imposed.

ISSN:0143-1161    

DOI:10.1080/01431168508948433

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Assessment and comparison of the spectral signatures from various grassland surfaces necessitated the measurement and recording of large amounts of reflectance data over short periods. A microcomputer data logger, based on a Synertek 6502 microprocessor was used to acquire these data and a modified motor vehicle was used to carry the radiometers and microcomputer during field experiments. A technique for measurement and estimation of reflectance factors is discussed to illustrate errors that may occur during collection and analysis of large amounts of ground-based reflection data when using various geometrical arrangements between targets and radiometers. Details of the hardware used and a listing of programmes used in the microcomputer system are published elsewhere

ISSN:0143-1161    

DOI:10.1080/01431168508948434

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

This paper reports a second year's (1981) results of a field geobotanical remote-sensing study in central Virginia, the objective of which was to investigate the relationship between mineralization and reflectance from vegetation. The objective of the 1981 work was specifically to test the generality and reproducibility of the previous year's results.

ISSN:0143-1161    

DOI:10.1080/01431168508948435

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Results of this study show that heavy rainfall in the Qinghai-Xizang Plateau area is usually preceded by a high growth rate of the convective clouds followed by a rapid collapse of the cloud top. The tops of the convective clouds associated with heavy rainfall over the plateau usually lie between the altitudes of the two tropopauses which exist over the plateau. Undoubtedly the double tropopause restricts the vertical growth of the clouds and this may be the reason why tornadoes rarely occur there

ISSN:0143-1161    

DOI:10.1080/01431168508948436

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

A climatology of Northern Hemisphere cyclonic cloud vortices is developed from high-resolution Defense Meteorological Satellite Program (DMSP) infrared imagery for mid-season months. The technique which is described involves pattern recognition using a detailed vortex classification system. Variations in hemispheric frequencies of successive vortex types are dominantly seasonal rather than latitudinal and imply a close association with surface (mainly cryosphere) variations. More extensive sea ice or snow cover in April and January is associated with increased cyclogenesis, indicating enhanced surface-atmosphere feedback. A significant relationship exists between cloud-vortex variations and the sea ice boundary, but not with the continental snowline

ISSN:0143-1161    

DOI:10.1080/01431168508948437

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

ISSN:0143-1161    

DOI:10.1080/01431168508948439

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor