ISSN:0143-1161    

DOI:10.1080/01431169408954152

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Simultaneous airborne measurements of sea surface temperature (SST) by an infrared (IR) radiometer and radar backscatter from a scattcromcter operating at the same C band as on ERS-1, were made over the Tyrrhenian Sea. The aircraft SST field showed part of the cold and warm eddy system characteristic of the region and compared well with ship-based measurements. The radar backscatter data were examined to investigate whether any dependence on SST could be discerned. It was found that the radar backscatter data gave a more intermittent view of the eddy and that view appeared to change from day to day. A change in the radar view of the eddy could occur due to changing wind fields or atmospheric stability patterns over the thermal front and this hypothesis was discussed with regard to two periods with different atmospheric conditions. For two days of very light winds and calm sea conditions the radar signature followed the main thermal gradient features and a positive, significant correlation was obtained between the SST and radar spatial patterns. For a further three days with moderate winds from the north to east quarter, a negative and generally weakening correlation was obtained with SST, with the radar view not identifying the major thermal gradients associated with the eddy.

ISSN:0143-1161    

DOI:10.1080/01431169408954153

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

For several years now NOAA/NESDIS have derived an operational global sea surface temperature (SST) product from the AVHRR instrument on the NOAA satellites. This is done using the MCSST and CPSST algorithms which contain coefficients that are determined from a regression analysis of satellite data againstin situsurface data. The current algorithms are used to provide global SST data without taking into account the latitude, climate or location of the satellite data, although the CPSST coefficients do have a weak dependence on the satellite brightness temperatures. Because of this global application the current SST algorithms have inherent errors due to local climate influences. In this paper a new SST algorithm is developed that does not rely on regression analysis to derive its coefficients. By using the spatial variation of the brightness temperatures in a small area (50 km by 50 km) it is possible to derive the appropriate coefficients to use in the algorithm. The SST field can thus be derived at any location without need for prior determination of the algorithm coefficients. In a simulation study, data from twenty-five radiosonde ascents-arc use with an atmospheric transmission model to derive a range of atmospheric transmittances and satellite brightness temperatures. Coincident AVHRR data and ship data are used to assess the accuracy of the new algorithm. The various dependencies of the terms in the SST algorithm are investigated. As with the MCSST and CPSST algorithms, the new method has largest errors when applied in situations of abnormal atmospheric structure. The improvement over the MCSST product may initially be only marginal, but with the advent of the more precise data from the Along Track Scanning Radiometer (ATSR) a more accurate global SST product may be possible.

ISSN:0143-1161    

DOI:10.1080/01431169408954154

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The distribution of suspended particles of different size is investigated using Landsat-TM in coastal waters near a sewage outfall, Sydney, Australia. Following a discussion of the relations between visible response and suspended particles a model is developed, via regression analysis, relating TM data and ocean sampled particle size data. This allowed the prediction of the number of particles in each of 36 classes of particle size. TM digital data was processed on the basis of the developed models to show the spatial distribution of both large and small particles. Large particles were found to be distributed near an ocean sewage outfall, while small particles were more widely distributed.

ISSN:0143-1161    

DOI:10.1080/01431169408954155

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Regional-scale behaviour of backscattering at C-band is investigated using data of the ERS-1 three-beam scatterometer, the AMI-WIND, during November 1991, over the Arctic ocean. The normalized radar cross-section appears as a linear function of incidence angle, whose two parameters vary considerably between zones of first-year and multi-year sea ice. Once determined the slope parameter of the AMI-WIND data, measured normalized radar cross-sections are corrected to bring them to a single reference incidence angle. False-colour mapping of this variable displays first-year and multi-year sea ice zones as determined previously from several passive micro-wave sensors (ESMR. SSM,/I)

ISSN:0143-1161    

DOI:10.1080/01431169408954156

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Marine operations in polar and subpolar regions rely on accurate sea ice information for operational planning purposes. Before venturing into operations, however, mapping of the prevailing sea ice conditions are important to feasibility analyses and planning of the operation. Multi-year sea ice information is often derived from passive microwave radiometers such as the Special Sensor Microwave Imager (SSM/I) on board the U.S. Defense Meteorological Satellite Program (DMSP) satellites, or the Scanning Multichannel Microwave Radiometer (SMMR) on board the Nimbus-7 satellite. These sources provide wide aerial coverage and all weather capability, but offer only low spatial resolution, 30 km. In contrast, the thermal infrared channel of the Advanced Very High Resolution Radiometer (AVHRR) on board the NOAA satellites, provides a 1 1km spatial resolution at nadir with a reasonable cost. A technique for extraction of multi-year sea ice information from thermal infrared AVHRR data was thus created. It relies on surface temperature differences between first-year and multi-year sea ice. Adjustments of the absolute concentration levels were made based on a regression relation between AVHRR and SMMR based multi-year sea ice concentrations. The technique is inapplicable during periods of dark, cloud cover, or melting conditions.

ISSN:0143-1161    

DOI:10.1080/01431169408954157

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

This paper describes the Greek University Departments and Government Institutes involved in the remote sensing application to geological sciences. Consequently, it reviews the geological-remote sensing investigations that have been carried out by the researchers of the above Departments/Institutes during the last 10 years

ISSN:0143-1161    

DOI:10.1080/01431169408954158

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Results are presented from a study in which texture measures are employed as a means of detecting urban dereliction, using the Potteries conurbation as a test site. Guided by the experience of using aerial photography for this task and also by a consideration of the workings of the human visual system, four texture measures, namely, standard deviation, entropy, run lengths and ‘fractal’ roughness, were selected for use with thermal band imagery. Standard deviation images show derelict sites to be characterised by frequent, low-intensity bound- aries whereas rural areas have few boundaries picked out and those of the urban area are high-intensity. Such images are potentially useful tools for monitoring the extent of derelict sites. Entropy images depict derelict land in mid-grey tones, between the high values characteristic of rural areas and the low values of urban areas. Run length images are perhaps the most successful at segmenting the derelict sites from the background but are most effective on large sites. The ’fractal’ roughness image bears a strong resemblance to the standard deviation measure. These are promising results, but futher work is necessary to integrate them into a classification methodology.

ISSN:0143-1161    

DOI:10.1080/01431169408954159

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Estimates of area by land cover category from photo interpretation are subject to bias arising from interpretation error. Quantification of this error by groundtruth survey allows corrections to be made to the estimates. The precision of estimates of interpretation error for a fixed cost depends on the survey design; simple survey designs arc inefficient for this purpose. The penalty for using more complex designs is that a sophisticated correction method is required. We note the assumptions of existing correction methods, develop a more general method, and show how the precision of corrected estimates of area may be quantified. We demonstrate the effect of‘correcting’ area estimates under different methods, and provide an example in which use of an inappropriate method leads to substantial bias (up to 40 per cent).

ISSN:0143-1161    

DOI:10.1080/01431169408954160

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Traditional methods of assessing satellite-derived landcover map accuracy are based on samples. In conditions of inaccessible terrain and lack of up-to-date contextual information, the verification of samples frequently is unfeasible. Such conditions are typical for many applications in developing countries and have been encountered by the authors when mapping the landcover of the region of Manaus in the central Brazilian Amazon Basin. Furthermore, sample-based methods fail to provide information on the spatial distribution of thematic map reliability. This article describes a procedure to derive reliability maps to accompany satellite-derived landcover maps.

ISSN:0143-1161    

DOI:10.1080/01431169408954161

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor