ISSN:0143-1161    

DOI:10.1080/01431169308904346

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

DMSP visual and infrared Operational Line Scanner (OLS) data reveal several effects of a mountain gap wind generated by wind flow through the Kamishak Gap on the west side of Cook Inlet, Alaska. The existence of the wind can be inferred through one of three separate effects apparent in the data: (1) a roughened sea effect, appearing as a dark grey shade swath within a sunglint pattern; (2) an anomalous grey shade effect induced by sea spray and aerosols, and, (3) a multiple cloud line effect originating as a result of a moisture flux from the sea to the air in a high speed, cold air, coastal outbreak. The Special Sensor Microwave Imager (SSM/I) of the DMSP satellite provides another means to detect the Kamishak Gap wind due to the sensitivity of this sensor to changes in microwave emission of the sea surface as a result of sea spray and foam in high wind speed areas and to associated changes in integrated water vapour content (oceanic total precipitable water). Developed algorithms provide a methodology to quantify from a satellite perspective some of the characterisitics of such events.

ISSN:0143-1161    

DOI:10.1080/01431169308904347

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Satellite data from the Arctic present extensive shaded zones arising from the combination of low Sun elevation and mountainous topography. Field radiometry measurements from training zones on two glaciers in Arctic north-west Svalbard discriminate the different surface states of the glaciers. The SPOT reflectance values have been corrected using the slope orientation and dip parameters from the digital terrain model combined with the corresponding Sun elevation and azimuth. The reflectances of the shaded and illuminated zones have been restored to a new image based on the XS3 versus XS1 bimensional histogram. The pixel values of the new image can distinguish between firn and superimposed ice surface states on the glaciers defined and controlled by field measurements. From the new image a map of the different surface states of the glacier can be produced which is homogeneous in both the shaded and illuminated zones. The boundary between the firn and the superimposed ice can be located on the median and longitudinal profile of the glacier by combining the new image and the digital terrain model. With this method it is possible to locate the boundary between the firn and the superimposed ice and, consequently, the equilibrium line to within 40 m of altitude.

ISSN:0143-1161    

DOI:10.1080/01431169308904348

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Presence of soil moisture in sufficient amounts is vital for proper seed germination and early growth of crops. For irrigation scheduling and crop yield forecast modelling, knowledge of soil moisture in the crop root zone is essential. Microwave remote sensing methods provide estimates of soil moisture only in the surface layer of thickness 0-5 cm.

ISSN:0143-1161    

DOI:10.1080/01431169308904349

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Studies on brightness temperature (TB) data of 325 passes acquired by Bhaskara-II satellite microwave radiometers (SAMIR) at 19 ⋅ 35, 22 ⋅ 235 and 31 ⋅ 4 GHz indicate that certain passes have interesting TB data trends over land and sea in spite of coarse ground resolution. Here an attempt is made to analyse such passes in terms of the ground features and agrochmatic conditions. Certain passes have shown more or less constant TB values over a long stretch of the pass. Average TB data values have been extracted from such passes and are summarized.

ISSN:0143-1161    

DOI:10.1080/01431169308904350

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The accuracy achievable in the surface soil moisture measurement of rough bare and vegetated soils, typical of the Italian landscape, has been investigated by using microwave experimental data collected by means of a multi-band sensor package (L, X, Kaand infrared bands). The thickness of soil that mainly affects the emission at the three microwave frequencies has been assessed. The sensitivity of L band emission to the moisture content of a soil layer about 5 cm thick has been confirmed, as well as the attenuation effect due to the surface roughness and presence of vegetation. A correction criterion based on the sensitivity to roughness and crop parameters of the highest frequencies (X and Kabands) is proposed in order to increase the precision in soil moisture measurements.

ISSN:0143-1161    

DOI:10.1080/01431169308904351

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

In a previous article we outlined the fundamental limits on the accuracy with which the focus parameter for SAR processing could be derived using autofocus techniques. This uncertainty has implications for the resolution which can be achieved in a SAR system. In the present article we analyse the effect of these errors on the resolution and sidelobe levels of the compressed pulse and discuss the implications for super-resolution techniques, which depend on detailed knowledge of the system response function.

ISSN:0143-1161    

DOI:10.1080/01431169308904352

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

In the previous paper we derived the fundamental noise limits in the determination of the autofocus parameter in SAR processing for both point and extended objects. In the present paper we extend this analysis to establish the fundamental limits on the image quality of a phase-corrected SAR image. A variety of autofocus schemes are analysed and an improved scheme is proposed which offers the minimum long-term image distortion and reasonable point response to changes in the autofocus parameter across the full aperture. The implications for phase correction based on autofocusing, leading to distortion-free images are examined. Image distortion, phase error and the point-target response are all derived as a function of the extent to which the full aperture is subdivided so as to match high-frequency changes in the focus parameter.

ISSN:0143-1161    

DOI:10.1080/01431169308904353

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Based on the generalization of compatible data on spectral brightness coefficients (SBC) and spectral albedo (SA) for the wavelength intervals 0 ⋅ 44-0 ⋅ 46 µm, 0 ⋅ 54-0 ⋅ 56 µm, 0 ⋅ 66-0 ⋅ 69 µm and 0 ⋅ 77-0 ⋅ 80 µm, average values of SBC were tabulated for typical surfaces of the U.S.S.R. territory. These data were used to map the summertime SBC values for the U.S.S.R. territory in the spectral intervals mentioned above and to perform their statistical analysis. A technique for drawing maps and for their analysis is given. The problem of the choice of the most informative spectral intervals for multi-purpose remote sensing of natural formations is discussed.

ISSN:0143-1161    

DOI:10.1080/01431169308904354

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

In a recent paper Eckstein and Simpson describe what they believe to be serious difficulties and/or errors with the CZCS (Coastal Zone Colour Scanner) processing algorithms based on their analysis of seven images. Here we point out that portions of their analysis, particularly those dealing with multiple scattered Rayleigh radiance, are incorrect. We also argue that other problems they discuss have already been addressed in the literature. Finally, we suggest that many apparent artifacts in CZCS-derived pigment fields are likely to be due to inadequacies in the sensor band set or to poor radiometric stability, both of which will be remedied with the next generation of ocean colour sensors.

ISSN:0143-1161    

DOI:10.1080/01431169308904355

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor