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Surface soil moisture was retrieved globally by systematically correcting for the effects of vegetation and soil surface roughness. The retrieval is enabled by employing physical-models of radar forward scattering for individual vegetation types to account for vegetation scattering and absorption, and by constraining the surface roughness effect using time-series observations. The L-band SMAP multi-polarized...
The distorted Born approximation (DBA) combined with the numerical solutions of Maxwell equations (NMM3D) has been used for the radar backscattering model for NASA's Soil Moisture Active Passive (SMAP) mission. The models for vegetated surfaces such as wheat, grass, soybean and corn have been validated with the Soil Moisture Active Passive Validation Experiment 2012 (SMAPVEX12) data. In this paper...
Tycho crater is the most prominent crater of Copernican era. In this paper, the spatial and temporal features of the microwave thermal emission (MTE) at Tycho area are studied with the microwave sounder (CELMS) data combined with TiO2 abundance, surface slope and roughness, rock abundance data of lunar regolith. The results indicate that MTE at the south part of Tycho crater (Region A) is strongly...
Global Navigation Satellite Systems Reflectometry (GNSSR) is a sort of multi-static radar using navigation signals as signals of opportunity. Due to the large number of transmitting satellites multiple scattering points over the Earth's surface can be simultaneously tracked, which provides wide-swath and improved spatio-temporal sampling over current space-borne radar altimetry missions. The lack...
Improved soil moisture estimation, within a combined radar-radiometer framework, by using Joint-physics modeling is demonstrated and presented in this work. Detailed numerical simulation on bare, but rough surfaces, highlight how improved emission-scattering modeling, can outperform conventional approaches. Root-mean-squared error statistics show almost a factor of two improvement in soil permittivity...
High Frequency (HF) radar sounder has been employed for the Mars surface/subsurface exploration. To survey the seasonal water flows on Mars surface, which has been reported, the radar sounder echoes from dry surface or water flowing surface are numerically simulated, respectively. Simulation results show that the radar echoes from water flowing surface is significantly larger than the dry surface,...
Soil moisture retrieval is important in microwave remote sensing, but its high dimensional and non-linearity make it difficult to realize. In this paper, an improved Fruit Fly Optimization Algorithm (IFOA) to optimize the Least Squares Support Vector Machine (LSSVM) Model is used for soil moisture retrieval. The sampling data for training and test is generated by using Advanced Integral Equation Model...
In the radar imaging of the object above three-dimensional (3-D) ocean surface, the multipath scattering brings in artifacts which can be reckoned as the distorted and shifted replicas of the direct-path scatters. As it is the propagation delays that play an important role in the understanding of these artifacts, this paper proposes a probability model of the multipath delays for the scatters above...
In this paper, we investigated the bistatic scattering of soil moisture and surface roughness of bare soil surfaces. We generated database by using an advanced integral equation model (AIEM). For better understanding the bistatic scattering characteristics of bare soil surfaces, we adopted single polarized simulations and combination of dual angular simulations. To explore the sensitivity of bistatic...
This work demonstrates a methodology to detect sea ice presence over the Arctic and Antarctic regions using Global Navigation Satellite Systems (GNSS)-Reflectometry (GNSS-R) data obtained with the UK TDS-1 satellite. The algorithm is based on estimating the degree of coherence of the received GNSS reflected waveform or Delay-Doppler Map (DDM). While at open ocean conditions, the scattered signal follows...
This paper presents bistatic scattering response of rice canopy over growth stages based on a three-layer microwave scattering model, which is developed using the iterative solution of the vector radiative transfer equations up to the second order, and the dense medium phase and amplitude correction theory (DM-PACT) is used to improve the phase matrix taking coherent effects into account. To validate...
In the terahertz (THz) band, materials that could be seen as smooth and homogeneous at microwave frequencies may display surface and volumetric scattering behavior. In this paper, we apply the integral equation method (IEM) and the vector radiative transfer (VRT) theory to simulate surface and volumetric scattering by a rough material boundary, respectively, in order to study the scattering characteristics...
Water Cycle Observation Mission (WCOM) is a mission dedicated to synergetic observations of global water cycle parameters, with emphasis on soil moisture, ocean surface salinity, snow water equivalent and frozen/thaw. WCOM implements its observation requirements by measurement of microwave emission/scattering of both the frequencies sensitive to the key parameters and also the auxiliary frequencies...
The aim of this paper is to estimate geometric, water and physical surface soil parameters from typical semi-arid regions made over bare study area (North Africa) using multi-temporal X-band SAR images (TerraSAR-X). For spatial and temporal surface roughness estimation, empirical relationships between radar and soil roughness parameters (rms height “Hrms”, and Zg parameter) were proposed. Two roughness...
Microwave-based retrieval of soil moisture in vegetated areas have uncertainties due the sensitivity of the signal to vegetation structure and dielectric constant. In this study, we propose a framework for developing a joint active L-band and active P-band retrieval algorithm to decrease the retrieval uncertainties. The algorithm focuses on the decomposition of soil, vegetation and dihedral components...
The PALSAR/PALSAR-2 contrast images are compared with the MODIS SST and Chl-a images. The comparison shows that the positions of line-shaped bright (ridge) patterns in the contrast images correspond with large SST gradients, i.e., SST fronts. Moreover, the comparison with the Chl-a image represents some local Chl-a maxima along the SAR ridge patterns in the PALSAR-2 contrast image, suggesting a general...
In this paper, the accuracies of existing theoretical reflection models for rough sea surfaces are examined. At first, we generated the sea surfaces using Pierson-Moskowitz ocean spectrum at various wind speeds. We calculated the significant wave height, RMS (root mean square) height and correlation height from the generated sea surfaces. And the forward reflection coefficients of the sea surfaces...
Land use and land cover change (LULCC) can influence regional climate by altering the surface roughness, soil moisture, and heat flux partition. LULCC information therefore is important for providing a better understanding of land-atmosphere interaction. A key requirement for such data for use in climate studies is the generation of land use maps on at least an annual basis. However, current continuous...
Global change has significant impact on permafrost region in the Tibet Plateau. Soil moisture of permafrost is the important factor influencing the energy flux, ecosystem and hydrologic process. Synthetic aperture radar (SAR) provides us a powerful tool to monitor the soil moisture. In this study, 19 scenes of German TerraSAR-X data are used to retrieve the soil moisture in Beiluhe, Northern Tibet...
Retrieval of sea surface wind speed from Synthetic Aperture Radar (SAR) data is one of the most widely used methods, since it can give higher resolutions than the other available surface wind sources. For this approach, two principal methods can be found: one is based on electromagnetic (EM) models and the other is based on empirical (EP) ones. In both indicated ways, the Geophysical Model Functions...
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