Soil Moisture Retrieval Using GNSS-R Techniques: Experimental Results Over a Bare Soil Field

Rodriguez-Alvarez, Nereida; Bosch-Lluis, X.; Camps, A.; Vall-llossera, M.; Valencia, E.; Marchan-Hernandez, J.F.; Ramos-Perez, I.

doi:10.1109/tgrs.2009.2030672

Cited by 205 publications

(142 citation statements)

References 21 publications

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“…The upper part of Figure 8b shows the SNRs of signals from GPS satellite G31 received by both vertically and horizontally polarized antennas vs. the elevation angle. A notch (the minimum oscillation observed in the interference signal) was shown in the solid line at about 20°, this agrees well with results reported in the literature [7], while the dash line shows damping oscillations. The difference is due to the fact that the phase of the vertical reflection coefficient experiences a sharp change from 0°to 180°at the Brewster angle.…”

Section: Comparison Of Received Signals From Two Antennas Before Rainsupporting

confidence: 92%

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GPS-R L1 interference signal processing for soil moisture estimation: an experimental study

Yan

et al. 2014

EURASIP J. Adv. Signal Process.

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Global positioning system reflectometry (GPS-R) is an emerging area of GPS applications in microwave remote sensing using multipath reflected signals. Soil moisture estimation is one of the many potential applications of the GPS-R technique. The focus of this study is on investigating the feasibility of soil moisture estimation based on GPS L1 band interference signals which can be readily captured using a low-cost off-the-shelf L1-band GPS receiver. The theoretical background is studied, and the field experiments conducted are described. Power spectrum analysis is performed on the received interference signals to determine the interference signal frequency variation, and cosine similarity is applied to identify the initial phase change. Data collected at a number of continuously operating GPS stations are also analyzed. The results demonstrate that both interference signal frequency and phase have changed significantly after rainfalls occurred. That is, it is possible to estimate soil moisture by analyzing the frequency change and phase shift. However, it is also observed that the phase shift is inconsistent in some cases. Ongoing work will focus on figuring out the source of the inconsistency so that reliable estimation of soil moisture can be achieved.

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Section: Comparison Of Received Signals From Two Antennas Before Rainsupporting

confidence: 92%

“…A number of experiments have been carried out for such an investigation [6,7]. An electrodynamics model for GPS direct and reflected signal interference has been developed by Zavorotny et al [8].…”

Section: Introductionmentioning

confidence: 99%

GPS-R L1 interference signal processing for soil moisture estimation: an experimental study

Yan

et al. 2014

EURASIP J. Adv. Signal Process.

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“…The variation of phase between the two signals causes constructive and destructive interferences that can be exploited to measure the soil moisture. This concept, called Interference Pattern Technique (IPT), has been extensively used by the Universitat Politècnica de Catalunya [17,103,104]. They used a specific receiver for GNSS-R, using vertically and horizontally polarized antennae instead of RHCP only.…”

Section: Gnss-r For Soil Moisture Recoverymentioning

confidence: 99%

Soil Moisture & Snow Properties Determination with GNSS in Alpine Environments: Challenges, Status, and Perspectives

et al. 2013

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Moisture content in the soil and snow in the alpine environment is an important factor, not only for environmentally oriented research, but also for decision making in agriculture and hazard management. Current observation techniques quantifying soil moisture or characterizing a snow pack often require dedicated instrumentation that measures either at point scale or at very large (satellite pixel) scale. Given the heterogeneity of both snow cover and soil moisture in alpine terrain, observations of the spatial distribution of moisture and snow-cover are lacking at spatial scales relevant for alpine hydrometeorology. This paper provides an overview of the challenges and status of the determination of soil moisture and snow properties in alpine environments. Current measurement techniques and newly proposed ones, based on the reception of reflected Global Navigation Satellite Signals (i.e., GNSS Reflectometry or GNSS-R), or the use of laser scanning are reviewed, and the perspectives offered by these new techniques to fill the current gap in the instrumentation level are discussed. Some key enabling technologies OPEN ACCESSRemote Sens. 2013, 5 3517 including the availability of modernized GNSS signals and GNSS array beamforming techniques are also considered and discussed.

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“…Both missions operate in the microwave L-band, which is most suitable for SM observations [12,20]. Moreover, first SM retrievals have been carried out by GNSS (Global Navigation Satellite System) reflectometry approaches [21][22][23][24][25][26][27], which analyse GNSS signals reflected from the soil. Depending on the moisture content in the soil, the reflected pattern changes, which is in principle quite similar to active microwave remote sensing.…”

Section: Introductionmentioning

confidence: 99%

Soil Moisture Retrieval Based on GPS Signal Strength Attenuation

Koch

Schlenz

Prasch

et al. 2016

Water

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Soil moisture (SM) is a highly relevant variable for agriculture, the emergence of floods and a key variable in the global energy and water cycle. In the last years, several satellite missions have been launched especially to derive large-scale products of the SM dynamics on the Earth. However, in situ validation data are often scarce. We developed a new method to retrieve SM of bare soil from measurements of low-cost GPS (Global Positioning System) sensors that receive the freely available GPS L1-band signals. The experimental setup of three GPS sensors was installed at a bare soil field at the German Weather Service (DWD) in Munich for almost 1.5 years. Two GPS antennas were installed within the soil column at a depth of 10 cm and one above the soil. SM was successfully retrieved based on GPS signal strength losses through the integral soil volume. The results show high agreement with measured and modelled SM validation data. Due to its non-destructive, cheap and low power setup, GPS sensor networks could also be used for potential applications in remote areas, aiming to serve as satellite validation data and to support the fields of agriculture, water supply, flood forecasting and climate change.

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Soil Moisture Retrieval Using GNSS-R Techniques: Experimental Results Over a Bare Soil Field

Cited by 205 publications

References 21 publications

GPS-R L1 interference signal processing for soil moisture estimation: an experimental study

GPS-R L1 interference signal processing for soil moisture estimation: an experimental study

Soil Moisture & Snow Properties Determination with GNSS in Alpine Environments: Challenges, Status, and Perspectives

Soil Moisture Retrieval Based on GPS Signal Strength Attenuation

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