ISSN:0143-1161    

DOI:10.1080/01431169408954278

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

ISSN:0143-1161    

DOI:10.1080/01431169408954279

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The Joint Research Centre “JRC” Ispra of the European Commission “EC” and the European Space Agency “ESA” supported and financed the deployment of the National Aeronautics and Space Administration “NASA” and the Jet Propulsion Laboratory “JPL” Co, L- and P-band polarimetric synthetic aperture radar “SAR” in Europe in mid-August 1989. The campaign was entitled MAESTRO I.

ISSN:0143-1161    

DOI:10.1080/01431169408954280

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Tests using MAESTRO data from the Reedham and Feltwell test sites suggest that the assumptions of a multi-variate complex zero-mean Gaussian distribution for scattering am litudes and a linear distortion model for polarimetric data lead to a viable model for C-band observations, though with some deviations between theory and measurements. P·band observations arc in general not consistent with this data model. When viable, the Gaussian model provides a basis for defining phase information, and has implications for the statistical measures which should be used to do so. The usual mean and standard deviation sta istics arc shown to have undesirable characteristics when applied to phase measurements. The effects of calibration and noise on phase measurements from distributed targets arc discussed, and other system effects on phase arc noted. Analysis of phase data from fields at the Feltwell test site shows that at C band the copolarized phase difference can discriminate between different crop types, but not at P band.

ISSN:0143-1161    

DOI:10.1080/01431169408954281

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Abstract. The results of an analysis of polarimetric P, Land C-band SAR data from the JPL AIRSAR of a forest area of maritime pine in Les Landes, southwest France, are described and discussed. The data were acquired in connection with the MAESTRO I Campaign organized by ESA and JRC/lspra. Cross-talk and channel imbalance distortions are removed in a calibration process using the SAR data itself and trihedral corner reflectors positioned at the scene. Two calibration methods have been implemented and compared: the iterative Klein algorithm and the non-iterative Quegan algorithm. Quegan's method shows the largest reduction of the cross-talk, and the most stable and easily interpreted results. Also, absolute calibration using the integral method has been performed. The results presented show that P band (and to some extent L band) is very sensitive to trunk biomass using single-polarization radar data, at least at the incidence angles in the range from 38° to 52°, whereas C band is less sensitive. Also, the cylinder model by Durden et al. of the baekseattering from a forest has been implemented and the results show good agreement with the SAR data. The dominant scattering mechanisms have been determined using the model at P and L bands.

ISSN:0143-1161    

DOI:10.1080/01431169408954282

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

In this paper we present a study on the application of polarimetric supervised classification techniques to the case of a forested area where the influence of topography is important. For the experimental part of the study, we use the polarimetric AIRSAR data at C, Land P band, acquired over the Black Forest near Freiburg “Germany” during the 1989 MAESTRO I Campaign. Two classification schemes are considered: one is of the classical Bayes type, while the other is based on the concept of maximum contrast. We show practical results of the use of both classifiers in a classification context based on tree age classes. Also the dependency of the classification accuracy on a number of parameters, such as calibration, feature vector dimensions and covariance matrix representation, is discussed. Finally, we focus on the influence of topography on classification and indicate how we can improve the classification results using a priori knowledge of the terrain slope.

ISSN:0143-1161    

DOI:10.1080/01431169408954283

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

In recent years, there has been an increasing interest in the use of radar data for observations of forest ecosystems. In particular, it was shown that the intensity of SAR images at L band was proportional to the forest aboveground biomass. More recently, the analysis of NASA/ JPL SAR data over the Landes forest “south-west France” revealed strong correlation between P-band backscatter and biomass of pine trees and related characteristics “tree age, height, diameter”. Also, similar relations have been obtained on two different forests “maritime pine at Landes forest, France, and loblolly pine at Duke forest, U.S.A.”. This paper presents a step further in the understanding of the observations. using theoretical modelling applied to calibrated SAR data to explain the radar backscatter from the forest canopy under study. The study is presented at P band, which was found to be an optimal frequency band for forest observations. It was found that the H H return is physically related to both trunk and crown biomass, whereas VV and particularly HV returns are linked to crown biomass. Through allometric equations, relations between radar backscatter intensities and most of the forest characteristics can thus be explained. The validated model has been used in a next step to simulate a diversity of forest and observation conditions. The results have been used for a preliminary assessment of the possibility of inverting SAR data into forest biomass.

ISSN:0143-1161    

DOI:10.1080/01431169408954284

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The potential of radar-based tree biomass estimation has been studied using polarimetric SAR data from the Freiburg test site of the MAESTRO I Campaign and scatterometer data from a test site in Finland. Using the Freiburg SAR data and polarizaiton synthesis, the most suitable polarization combination was obtained. In P band, the maximum correIalions, which were found ncar the linear H V polarization, were up to 0·75.

ISSN:0143-1161    

DOI:10.1080/01431169408954285

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

MAESTRO I data from the Flevoland lest site in the Netherlands have been used for this study. From a complementary ground data collection, the bole volumes of a large number of stands of mainly poplar and ash have been estimated. The relationships between radar backscattering and bole volumes have been examined experimentally and theoretically. In the case studied, the radar backscattering sensitivity to bole volumes increases as the wavelengths increase. and is highest at P band. The sensitivity of the radar backscattering to variations of forest canopy components and moisture contents has been investigated theoretically at P band. It is important to obtain information on such variations before the inversion problem can be solved. The present study indicates a potential for bole volume determination by P-band SAR.

ISSN:0143-1161    

DOI:10.1080/01431169408954286

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Global monitoring of forest extent and changes of extent with time are vital not just to provide a continuous assessment of a renewable resource essential to mankind but also to give an input to models of the global carbon cycle and of climate change. Microwave remote sensing is a potential means to accomplish this objective. However, to determine the optimum characteristics of a satellite synthetic aperture radar (SAR) for reliable forest monitoring it is first necessary to validate modelled microwave backscatter relationships in studies of relatively small areas using data from aircraft SAR systems and from detailed ground survey.

ISSN:0143-1161    

DOI:10.1080/01431169408954287

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor