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Recent theoretical and experimental studies have indicated the feasibility of passive microwave L-band observations for observing dry snow cover characteristics, namely snow density in the lower approx.. 10 cm of the snowpack. The sensitivity of L-band emission to snow density is based on the dual influence of refraction and impedance matching on observed brightness temperature with changing effective...
The Global Satellite Mapping of Precipitation product (GSMaP)[1], is a recent solution of satellite-based precipitation estimates which provides global rainfall products of high spatial (0.1°) and temporal resolutions (1 hour). This paper presents a study of GSMaP precipitation products (GSMaP_MVK and GSMaP_Gauge) for a torrential precipitation event in Jinghe Basin (from 06:00 AM on 22 July 2010...
Radio frequency interference (RFI) is one of the most significant limiting factors in the retrieval of geophysical parameters measured by microwave radiometers. In this work, based on the measured visibilities of European Space Agency's Soil Moisture and Ocean Salinity (SMOS) mission, RFI mitigation results are presented using two approaches of array factor synthesis of synthetic aperture interferometric...
Microwave interferometric radiometer (MIR) is a passive sensor using synthetic aperture technique for microwave remote sensing. Antenna array configuration is the first concern for the MIR application. Various array configurations have been proposed. This paper presents the analysis of the circular array performance and compares it with the Y-shaped array and hexagonal array. Based on the early developed...
Global soil moisture is one of the critical land surface initial conditions for numerical weather, climate, and hydrological predictions. Since it is not practical to provide global maps using ground measurements, land surface soil moisture remote sensing has been a hot research topic in the last several decades. As a result, a number of soil moisture products have been produced from different satellite...
Field experiments have played a critical role in the development and implementation of satellite soil moisture missions. A review of key experiments is presented that includes tower-, aircraft, and satellite-focused efforts conducted over four decades that have supported two dedicated satellite missions; Soil Moisture Ocean Salinity (SMOS) and Soil Moisture Active passive (SMAP).
Aquarius is an L-band active/passive sensor designed to globally map sea surface salinity from space [1, 2]. Two instruments, a radar scatterometer and a radiometer, observe the same surface footprint almost simultaneously. The radiometer is the primary instrument for sensing sea surface salinity (SSS), while the scatterometer is included to provide a correction for sea surface roughness, which is...
Aperture synthesis with high spatial resolution would seriously increase the hardware requirements and system complexity. To reduce the system complexity, Rotating mirrored aperture synthesis (RMAS) that combines the antenna array rotation with mirrored aperture synthesis was proposed to reduce the number of antennas. In this paper, the sieving method is presented to optimize the array configuration...
A recently developed microwave radiometric technique, known as wideband autocorrelation radiometry (WiBAR), offers a deterministic method to remotely sense the propagation time τdelay of multi-path microwave emission of low-loss terrain covers and other layered surfaces. Terrestrial examples are the snow and lake ice packs. The microwave propagation time τdelay through the pack yields a measure of...
This paper presented a pixel-based statistical regression method based on a high-resolution snow depth product to improve the accuracy of passive microwave snow depth retrievals. The statistical regression relation was established based on a linear relationship between the snow depth and the brightness temperature (TB) difference. The coefficients of these regression equations were derived using the...
Freeze and thaw (FT) processes have profound impact on the terrestrial water cycle, net primary productivity, carbon cycle, surface energy budget and hence the global climate system. The available passive microwave based FT states data are basically developed from brightness temperatures, which themselves affected by atmospheric water vapor content. Since land surface emissivity estimates derived...
QP model with dual-channel algorithm could accurately represent the effect of surface roughness on emission at different polarization under big view angle. The purpose of this paper is to estimate long temporal series soil moisture product based on the QP algorithm, and compared it with JAXA, LPRM in Genhe basin. The results indicate that QP retrieval values are closest to the ground data but it have...
The SMAP (soil moisture active passive) which is one of the satellites that specifically designed for soil moisture monitoring, was launched on 31 January 2015. Recently, the SMAP radiometer soil moisture product has been released to the public. It is very urgent to evaluate the reliability of this product before it can be widely used in hydrometeorological studies. In the study, we carried out an...
Soil moisture is a critical factor in cosmopolitan meteorological and hydrological processes. Microwave remote sensing brightness temperature is sensitive to soil moisture through the effects of moisture on the dielectric constant and hence emissivity of the soil [1]. It was found that the brightness temperature at L-band is useful for retrieving near-surface soil moisture [2–3]. The Soil Moisture...
The main objective of SMOS over land is to retrieve soil moisture. Anyway, for soils covered by vegetation two model parameters, soil moisture and vegetation optical depth, are provided as outputs of the Level 2 algorithm.
This study focuses on the calibration of the effective scattering albedo (ω) of vegetation in the soil moisture (SM) retrieval at L-Band. Currently, in the SMOS Level 2 and 3 algorithms, the value of ω is set to 0 for low vegetation and ∼ 0.06 – 0.08 for forests. Different parameterizations of vegetation (in terms of ω values) were tested in this study. The possibility of combining soil roughness...
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