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Due to the effects of the earth's rotation and the satellite's elliptical orbit, the Doppler centroid varies along the orbit in geosynchronous earth orbit synthetic aperture radar (GEO SAR). With an ultrahigh orbit height, the beam may illuminate outside the earth surface with a rotation angle large than 9 degrees. Therefore, the usual attitude steering methods to minimize the Doppler centroid in...
In order to measure the ocean surface current vector in a direct way, an interferometric method using pencil-beam scatterometer is proposed and the parameters of the traditional scatterometer are modified. What's more, the measurement principle and correlation model are introduced in this paper. The simulation results show that the Std of ocean surface current speed in both along-track and cross-track...
This paper presents a result of crossover analysis between HY-2 and Jason-2 mission over ocean. The major objectives of this paper are to assess HY-2 IGDR (Interim Geophysical Data Record) derived SSHs by comparing HY-2 measurements with the reference mission Jason-2, and further to illustrate the potential of HY-2 data in monitoring global sea level variability. The instrument-independent models...
The scatterometer on HY-2A, which is a spacebome real aperture Ku band radar with high radiometrie resolution and stability, can be used for determination of wind fields at the ocean surface. In this paper, the method of the internal calibration and the external calibration on HY-2A are described and detailed results are provided.
For the operational spaceborne scatterometers, there is no effective way to eliminate the influence of the rain. Echoes contaminated by the rain are discarded directly. In this paper, a special designed spaceborne scatterometer and its decoupling methods of echoes from sea surface and rain are introduced. The main steps of decoupling methods are as follows. First, the scatterometer system parameters...
This paper present an efficient matrix inverse algorithm of the recent iterative adaptive approach (IAA) in the application of real beam superresolution (RBS). Based on the inherently band structure of the covariance matrix, the computational complexity of inverse can be reduced by avoiding the computation of zero elements. To achieve this, the divide and conquer (D&C) method will be introduced...
CryoSat's Synthetic Interferometric Radar Altimeter (SIRAL) [1] is a Ku-band pulsewidth limited radar altimeter that transmits pulses at a high pulse repetition frequency thus making the received echoes phase coherent and suitable for De-lay/Doppler processing [2]. Moreover SIRAL takes advantage of two antennas mounted across-track for interferometric capability, in order to determine the across-track...
Theoretical model for return waveform was developed for underwater ultrasonic sonar with wide antenna beam at vertical sounding. First time the analysis of return waveform was used in acoustic system for measurement of significant wave height as in radio altimeter. New retrieval algorithm was developed for scheme of measurement and the advanced underwater acoustic “altimeter” can measure the significant...
Geostationary Doppler weather radar (GDWR), which is a novel and challenging instrument concept, can provide reflectivity profiles and Doppler dynamic information of meteorological targets over a circular disk coverage of approximately 5300km in diameter on the earth. In this paper, we estimate the mean Doppler radial velocity and Doppler spectrum width of GDWR, which have not been studied in the...
This paper present a superresolution algorithm for forward-looking imaging of scanning radar based on weighted least squares method. This algorithm utilized the weighted vectors to structure the objective function, and introduced the diagonal loading technique to obtain more robust superresolution result. Simulation results verified the performance of our algorithm.
This paper presents a novel phase correction technique for Passive Radar which uses targets of opportunity present in the target area as references. The proposed methodology is quite simple and enables the use of low cost hardware with independent oscillators for the reference and surveillance channels which can be geographically distributed.
The objective of this study was to analyze the L-band SAR backscatter sensitivity to forest biomass for Eucalyptus plantations. The results showed that the radar signal is highly dependent on biomass only for values lower than 50 t/ha, which corresponds to plantations of approximately three years of age. Next, Random Forest regressions were performed to evaluate the potential of PALSAR data to predict...
The Geoscience Laser Altimeter System (GLAS) has provided a useful dataset for estimating forest height in many areas of the globe. Most of the studies on GLAS waveforms have focused on natural forests and only a few were conducted over forest plantations. The objective of this study was to test the best known models used for estimating canopy height and above ground biomass of intensively managed...
Estimating forest above-ground biomass (AGB) and monitoring its variation are relevant for sustainable forest management, monitoring global change, carbon accounting, particularly for the Qilian Mountains (QMs), a water resource protection zone. In this work, the results of above-ground biomass (AGB) estimates from Landsat Thematic Mapper 5 (TM) images and field data from the fragmented landscape...
In this paper the results obtained during the CATARSI project have been shown. The aim was to implement an algorithm capable to extract soil moisture and vegetation biomass from SAR data at both L and X bands. An algorithm based on Artificial Neural Networks was tested on SAR images collected in 2010 during the BioSAR (L-band) campaign in Sweden for the retrieval of forest biomass and in 2010–2012...
The objective of this study is to retrieve a spatially-explicit map of forest biomass, which is not only an important parameter to evaluate carbon storage but also a necessary initial value for process-based carbon cycle models to simulate carbon dynamics within a region. In this study, we used the latest eighth national forest inventory statistics (2009–2013) and the MODIS Land Cover Type product...
Forest biomass reflects the ecological succession and human disturbance of the forest, and can fully embody the quality of forest ecosystem environment. The Qilian Mountain forest reserve at upper reaches of the Heihe River Basin was selected for the study. Landsat Thematic Mapper 5 (TM) images were selected as the source data, which were rectified by SCS + C terrain radiometric correction. Forest...
The purpose of this study is to estimate forest biomass using ALOS PALSAR imagery and forest inventory data. Above all, it is only appropriate for farmland which is small biomass values in the case of SAR Sigma-nought(o0), and is affected by shadow of bidirectional effects. On the other side, the terrain slope parameters are calculated using an estimation of the gradients in the two directions of...
In order to trace and identify the achievements of forest resources protection and development in China, the system of forest resources monitoring was built up to annually collect the forest information base on high-resolution data. The measurement analysis of forest resource was done in the 41 key counties. High-resolution SPOT5 images, RapidEye and other high-resolution remote sensing data had been...
Assessment of land condition is a basic prerequisite for finding the degradation of a territory under climatic and human pressures leading to desertification. The temporal change in vegetation productivity is a key indicator of land degradation. In this paper, taking the Beijing-Tianjin dust and sandstorm source region (BTDSSR) as a case, the annual-maximum normalized difference vegetation index (NDVI_max)...
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