ISSN:0143-1161    

DOI:10.1080/01431169208904276

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

BEPERS-88 was an extensive field campaign on the use of Synthetic Aperture Radar (SAR) in sea ice remote sensing in the Baltic Sea. This experiment was performed in order to study the possibilities of using the ERS-1 satellite SAR (and radar altimeter) in connection with the brackish ice in the Baltic Sea. The Canada Centre for Remote Sensing CV-580 C/X-band SAR was flown and an extensive validation programme was carried out. The data have been used for SAR image analysis, backscatter investigations, geophysical validation of SAR over sea ice, and evaluation of the potentials of SAR in operational ice information services. The results indicate that SAR can be used to discriminate between ice and open water, classify ice types into thrcc categories, quantify ice ridging intensity, and determine the ice drift. As an operational tool SAR is expected to be an excellent complement to NOAA imagery and ground truth.

ISSN:0143-1161    

DOI:10.1080/01431169208904277

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A helicopter-borne 8-channel ranging scatterometer HUTSCAT (Helsinki University of Technology Scatterometer) was used to investigate the backscattering behaviour of low-salinity sea ice at 5-4GHz and 9-8 GHz. The measurements were conducted during the BEPERS-88 Sea Ice Campaign in the Gulf of Bothnia, 6-12 March 1988. The backscattering properties of several sea ice types were examined at the two frequencies, using HH, VV, HV, and VH polarization modes. An incidence angle of 23° off nadir was used in order to investigate the feasibility of the ESA ERS-I (launched in July 1991) SAR for sea ice mapping. The capability of the new scatterometer to identify sea ice types was examined using the following radar output products at 8 channels: (a) the backscattering coefficient and (b) the characteristics of the radar return versus range spectrum (range resolution 65 cm).

ISSN:0143-1161    

DOI:10.1080/01431169208904278

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

In the Bothnian Experiment in Preparation for ERS-1 (BEPERS-88) airborne laser profiles and Synthetic Aperture Radar (SAR) images were obtained simultaneously over the pack ice in the Bay of Bothnia, Baltic Sea. The possibility of mapping ice ridging characteristics using SAR has been analysed. SAR intensity histograms and ridging statistics have been compared in regions with length scales from 3 to 23 km. The measures for the intensity of ridging were taken from the profilometer data as functions of the number of ridges and mean ridge height. The results show that, from SAR intensity distribution, an average of 10 per cent upper tail divided by the overall average is a good predictor for the ridging intensity. This predictor explains 80-90 per cent of the variance.

ISSN:0143-1161    

DOI:10.1080/01431169208904279

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

During March 1988, detailed measurements of the physical properties and depth distributions of the snow cover on the sea ice in the Gulf of Bothnia were made as part of BEPERS-88 (Bothnian Experiment in Preparation for ERS-1). The observations included profiles of the density, crystal structure. salinity, temperature, and brine volume (at 1-2 cm depth intervals), and 1084 snow depth measurements. These data are presented along with discussions of the implications of the measured properties for the interpretation of SAR imagery, and the use of laser profilometry for remotely estimating ice surface roughnesses.

ISSN:0143-1161    

DOI:10.1080/01431169208904280

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Airborne Synthetic Aperture Radar (SAR) data have been analysed together with in situ measurements of sea ice during the Bothnian Experiment in Preparation for ERS-1 (BEPERS) in March 1988. Based on the physical properties of the snow-covered level ice, a scattering model is used to predict the C-band like-polarization backscattering coefficient in an experiment area. Both the average backscattering coefficient and the SAR image texture were found to be in good agreement with the scattering model predictions. The backscatter signature of the level ice was found to be dominated by the ice surface r.m.s. height and autocorrelation function. These parameters were determined from profiles of the ice surface height, which were measured using a laser profiler device with sub-mm accuracy. The present model is expected to be accurate when the backscattering is dominated by scattering from the cm-scale snow or ice surface roughness.

ISSN:0143-1161    

DOI:10.1080/01431169208904281

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The variation of the surface backscattering of ice ridges for frequency 5-3 GHz is examined with a three-dimensional geometrical model for ice ridges and small scale perturbation theory. Multiple reflections are not included. The most important ridge properties for low salinity ice studied during the BEPERS experiment are the small scale surface roughness, the dielectric constant and the detailed ridge geometry parameters (like ice block orientations, etc.) in that order. The incidence angle distribution of an ice ridge is also affected by the minor facets of the ice blocks, For BEPERS ridges and radar parameters the contribution of single specular reflections to the backscattered intensity is not large.

ISSN:0143-1161    

DOI:10.1080/01431169208904282

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

This paper investigates the potential of ERS-l SAR imagery for sea ice classification. Two classification approaches, a pixel-based and a region-based, are developed and compared using the BEPERS-88 airborne SAR imagery together with the aerial photography for reference. The pixel-based approach is based on adaptive filtering, while the region-based approach is based on segmentation using edge detection with a region growing algorithm. The latter gives the better result as found by inspecting the confusion matrices and the classified images. The region-based method is tested on a simulated ERS-l Fast Delivery imagery based on BEPERS-data. It is shown that for the studied case a classification accuracy of 80 per cent is obtained when classifying the ERS-l SAR image into four classes (open water, level ice, brash ice and rubble fields). A classification accuracy of 90 per cent is obtained for three classes when brash ice and rubble fields are combined.

ISSN:0143-1161    

DOI:10.1080/01431169208904283

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor