Journal of Earth Science & Climatic Change
Open Access

The apace growing range of real aperture and synthetic aperture radars (SARs) dedicated to Earth observation provides these days a really broad coverage across area, time, and therefore the spectrum. Terribly massive quantities of information and pictures are being consistently collected, processed, and stored. The unrestricted, day, and night capabilities of those measuring device sensors allow acquisition of knowledge underneath conditions that don't seem to be doable with EO sensors. Radars will monitor iceberg position, movement, and age to enhance safety bewildered. They will give helpful data on oceans and their currents. Radars also can explore areas of the world, providing a listing of potential natural resource, new transportation routes; fresh provides, sites for agriculture, and so on. The papers reflect some of the many varied applications of radar that are being researched today.

Synthetic aperture radar, whether from space or airborne platforms, continues to attract much attention. Spatial resolutions of the order of 1 m are currently available from space-based SAR systems such as Terra SAR-X, whilst airborne spotlight SAR systems can achieve resolutions of the order of 10 cm. Many space-based types of radar are now fully polar metric, and there is considerable scope for interferometry SAR operation, either using repeat-pass methods or tandem platforms. In their paper entitled Scattering-based model of the SAR signatures of complex targets for classification applications present a method for analysing SAR imagery and the scattering from complex targets [1]. This has led to a proposed method for classifying targets such as ships and urban buildings, using features obtained from polar metric and interferometry SAR images.

Interferometry techniques can also be applied to analyse the movement of targets in an SAR image describe a technique for detecting radially moving targets in an SAR image in their paper “Multi-channel along-track interferometry SAR systems: Moving targets detection and velocity estimation [2].” They consider the performance of multichannel AT-In SAR systems in terms of moving target detection and the accuracy of radial velocity estimation.

Polarimetric data can also be successfully used for classification purposes in inverse synthetic aperture radar (ISAR) images, as described in “CLEAN technique for polarimetric ISAR” This paper addresses the problem of estimating the position and the scattering vector of target scattering centres from polarimetric ISAR images. The CLEAN techniques are used for reducing the data size of the images without losing useful information, with the aim of classifying and recognizing objects on the Earth surface.

A very interesting area of research in the last few years concerns the applications of passive SAR biostatic systems. In the paper entitled “Experiences gained during the development of a passive BSAR with GNSS transmitters of opportunity,” present an overview of the research conducted at the University of Birmingham in the area of space-surface biostatic synthetic aperture radar (SSB-SAR) since 2003. The main aim of the research is to experimentally demonstrate the feasibility and performance of airborne SS-BSAR, utilizing the Global Navigation Satellite System (GNSS) as the transmitter of opportunity. The paper highlights and briefly discusses the various factors that determine image quality, including various systems parameters, signal processing algorithms and specific problems to be addressed.

The problem of the correct reconstruction of an image is also the topic. Enhanced radar imaging in uncertain environment: A descriptive experiment design regularization approach [3]. A new robust technique is developed by the authors for high-resolution reconstructive imaging, applied to enhanced remote sensing (RS) with an imaging array radar and/or a synthetic aperture radar (SAR), operating in an uncertain RS environment. The operational scenario uncertainties are associated with the unknown statistics of perturbations of the signal formation operator (SFO) in a turbulent medium, imperfect array calibration, finite dimensionality of measurements, uncontrolled antenna vibrations and, in the case of SAR [4], random platform trajectory deviations. In that paper, the authors propose new descriptive experiment design regularization (DEDR) approach to treat the uncertain radar image enhancement/reconstruction problems.

Another important research area for remote sensing is the application of satellite imagery for damage assessment in “Damage detection from SAR imagery: application to the 2003 Algeria and 2007 Peru earthquakes,” describe a method for fusing remotely sensed radar imagery with geographic databases. The method is illustrated by analysis of real radar imagery. It can provide rapid assessment of earthquake damage although further work is needed to improve the accuracy that can be achieved.

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