摘要:

Incomplete vegetation canopies are complex remote-sensing targets. The directional variability of sensor response when viewing a cotton row crop with 48 per cent ground cover was documented for the thermal infrared region. The geometric structure of the canopy was described and radiometric temperatures of four components, sunlit and shaded vegetation and soil, were measured. These data were used to validate and verify a geometric, row projection model. The model predicts the thermal infrared response of a sensor as a function of sensor view angle, component temperature and geometry structure of the canopy. The field data showed sensor response differentials as great as 16.2°C when going from a zenith view angle of 0° to one of 80° in a plane normal to the row direction. The root-mean-square deviation between the model prediction and measured sensor response for all measurement periods and view angles (n = 90) was 0.96°C. The model serves as a sound mathematical basis for interpreting remotely-sensed data from row crops, and optimizing the directional view for specific canopy structures and environments.

ISSN:0143-1161    

DOI:10.1080/01431168308948548

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

A radiative transfer model was used to convert ground-measured reflectances into the radiance at the top of the atmosphere, for several levels of atmospheric path radiance. The radiance in MSS 7 (0.8-1.1 μm) was multiplied by the transmission fraction for atmospheres having different levels of precipitable water. The radiance values were converted to simulated Landsat digital counts for four path radiance levels and four levels of precipitable water. These values were used to calculate the Kauth-Thomas brightness, greenness, yellowness and nonesuch factors. Brightness was affected by surface conditions and path radiance. Greenness was affected by surface conditions, path radiance and precipitable water. Yellowness was affected by path radiance and nonesuch by precipitable water, and both factors changed only slightly with surface conditions. Yellowness and nonesuch were used to adjust brightness and greenness to produce factors that were affected only by surface conditions such as soils and vegetation, and not by path radiance and precipitable water.

ISSN:0143-1161    

DOI:10.1080/01431168308948549

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The growth of healthy green crops is proportional to the solar radiation intercepted and the fraction of light intercepted by the cropfis the major source of variation in crop yields. A two band spectrophotometer was used to measure solar radiation reflected from crops of sugar beet in the red (600-660 nm) and the near-infrared (780-940 nm) bands. The ratio of infrared/red reflected fluxes increased with the percentage of the ground covered by healthy green leaves and was used to estimatefOn the assumption that the efficiency with which crops convert radiant energy to biomass ϵ is constant, such measurements were used to determine future rates of growth and predicted the yield of an independently grown crop to within 6 per cent. Preliminary evidence suggests that spectral ratios may also be sensitive to changes in ϵ and the extension of these techniques to crops limited by disease or environmental stress is discussed.

ISSN:0143-1161    

DOI:10.1080/01431168308948550

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Images obtained from the Landsat multispectral scanner are not provided in any normally recognized map projection system, so it is often necessary for a transformation to be made. This is usually done with the aid of ground control points, whose locations on the ground (or on a map)are accurately known and which can be accurately located within Landsat images. The initial selection and location of such ground control points is usually performed manually

ISSN:0143-1161    

DOI:10.1080/01431168308948551

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The utility is assessed of remotely-sensed chlorophyll data in biological oceanography. Oceanographic data, highly resolved in the vertical, are used as a basis for estimating the (weighted) proportion of the water-column chlorophyll chat is accessible to the remote sensor. Examples are calculated for the continental shelf off Nova Scotia, the Canadian Arctic and the coast of Peru. The analysis is extended to the estimation of phytoplankton production. Remotely-sensed data contain only a small (5 per cent of phytoplankton biomass and 11 per cent of the turnover), but surprisingly stable, fraction of the information for the water column. A modest ground-truthing programme is required to exploit these data to the best advantage.

ISSN:0143-1161    

DOI:10.1080/01431168308948552

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

This study has been made in connection with the investigation ‘Heat capacity mapping missions 050’ (Cassinis and Lechi 1981), in order to evaluate the potential of thermal remote sensors in discriminating lithological units on the earth's surface. Discrimination is based on different thermal inertia of rocks which, in turn, is evaluated from the measurement of the difference λT between the maximum and minimum value of the temperature of the ground surface during the day. The simulation model consists of an ‘island’ formed of blocks of three materials having different thermal inertia and surrounded by water (with very high apparent thermal inertia). The behaviour of surface temperature has been calculated in the hypothesis that only conduction governs the process and the thermal diurnal cycle is constant at a given latitude and season. The conclusion of the simulation study is that the difference λT = Tmax− Tmin, changes quite abruptly at the boundary between the blocks but remains fairly constant inside each material. The minimum contrast of thermal inertia needed to produce an observable λT has been determined.

ISSN:0143-1161    

DOI:10.1080/01431168308948553

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The practical experience obtained by our participation in the European project TELLUS (a part of the HCMM programme) led us to state that the thermal inertia concept and sophisticated models are useful for understanding basic processes and for performing informative simulations, but cannot be used for a real estimation of evaporation

ISSN:0143-1161    

DOI:10.1080/01431168308948554

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Methods of measuring wind across a microwave propagation path are examined and specific problems involved are discussed. Both the initial slope and the time-delay method are considered and the use of a filter in the time domain for changing the shape of the weighting functions is examined. An experiment that has been carried out at X-band along a 37 km propagation path over hilly terrain is described. In this experiment emphasis has been given to straightforward procedures for inferring the wind across the path by making use of simple wind models valid for some kind of air circulation. A comparison of the results with data obtained from conventional wind measurements is reported.

ISSN:0143-1161    

DOI:10.1080/01431168308948555

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Lidar signatures from fogs can be affected by a substantial contribution from multiple scattering. This latter is strongly dependent on the aperture a of the receiver's field of view. Since lidar IROE IV allows the use of different values of α, an analysis is made of an approximate procedure to process the data in order to extract the single scattering contribution to the received power. Some experimental results are presented.

ISSN:0143-1161    

DOI:10.1080/01431168308948556

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

An integral relation has been obtained between variations of the brightness temperature for ground-based microwave radiometry and meteorological parameters of the atmosphere which permits a general approach to the statement of inverse problems of thermal and humidity sensing in the microwave range

ISSN:0143-1161    

DOI:10.1080/01431168308948557

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor