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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Investigation of Doppler Spectra of Sea Backscatter Through Large-Scale Monte Carlo Simulations: Direct Numerical Solution And Approximate Models
摘要： The study simulates and analyses backscattering of a time-harmonic (continuous-wave) X-band signal from evolving ocean-like surfaces in the 2D space. For the same surface realization, the scattered field is evaluated using the direct numerical solution of a first-principles boundary integral equation, and with two approximate models: the coherent Two-Scale Model (CTSM) and the second-order Small Slope Approximation (SSA2). Large Monte Carlo ensembles are built up to evaluate well-averaged Doppler spectra. The investigation focuses on the two spectral parameters: centroid and width, with alternative definitions for the latter being discussed. A broad and finely sampled range of incidence angles is considered, providing a comprehensive and detailed view at the behavior of these quantities from nadir to low grazing. Using the same set of surfaces when calculating backscattered fields according to the exact and approximate methods provides a rigorous test for the accuracy of the chosen scattering models. The reported high-quality data from direct numerical simulations can serve as a benchmark for other scattering formulations.
关键词： numerical simulations,sea surface electromagnetic scattering,Doppler spectrum
更新于2025-09-23 15:21:21
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[Methods in Molecular Biology] Immunological Tolerance Volume 1899 (Methods and Protocols) || Improvement of Signal-to-Noise Ratio for MST Radar Using Weighted Semi-parametric Algorithm
摘要： The Indian mesosphere–stratosphere–troposphere (MST) radar is the prominent atmospheric radar that provides the atmospheric movements’ information. The radar data is analyzed to obtain the wind parameter that requires the power spectral estimation. At higher altitudes, the estimation of Doppler spectrum is found to be unsatisfactory using both parametric and nonparametric methods for spectral estimation. In this article, the hyperparameter-free, weighted sparse iterative covariance-based estimation (SPICE) method has been considered. Unlike existing SPICE method, a different hyperparameter–free, weighted SPICE method has been derived using a gradient approach with different step sizes. The two versions of SPICE algorithm, i.e., SPICEa and SPICEb, are applied to the practical MST radar data collected at National Atmospheric Research Laboratory, Gadanki (13.5°N, 79.2°E). The obtained results are evaluated with the existing atmospheric data processor results which use the basic periodogram method. The proposed method shows the signi?cant enhancement in signal-to-noise ratio even at elevated heights.
关键词： Gradient approach,Doppler spectrum,MST radar,SPICE
更新于2025-09-19 17:15:36
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Analysis of Marlene Radar Data: Focus on Doppler Spectra and Group Lines
摘要： This paper deals with some results of the campaign called MARLENE (for MediterraneAn RFC and cLutter Environmental Experiment), already presented in [1]. During the campaign, radar data were acquired at C, X, Ku, Ka and W bands leading to a large amount of results at low grazing angle with a very high spatial resolution. Doppler spectra in VV polarization with large Doppler shifts are presented here. Then, a focus on the dispersion diagram (2D Fourier transform of the RCS in space and time) is carried out. Finally, a study of the low-frequency pattern observed in the dispersion diagram, called group line, is introduced.
关键词： dispersion diagram,Low-grazing measurements,sea surface radar scattering,Doppler spectrum
更新于2025-09-09 09:28:46