The Eddy Experiment: GNSS‐R speculometry for directional sea‐roughness retrieval from low altitude aircraft

Germain, Olivier; Ruffini, Giulio; Soulat, F.; Caparrini, M.; Chapron, Bertrand; Silvestrin, Pierluigi

doi:10.1029/2004gl020991

Cited by 75 publications

(39 citation statements)

References 18 publications

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“…[30] In this paper we have highlighted an inexpensive, passive, dry operational sensor concept for use on coastal platforms and aircraft (for airborne applications focusing on sea state, see, e.g., Zavorotny and Voronovich [2000] as well as Germain et al [2003]). Oceanpal is to provide precise sea level information and sea state, and we believe it will occupy an important niche in operational oceanography and marine operations.…”

Section: Discussionmentioning

confidence: 99%

Sea state monitoring using coastal GNSS‐R

Soulat

Caparrini

Germain

et al. 2004

Geophysical Research Letters

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118

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[1] We report on a coastal experiment to study GPS L1 reflections. The campaign was carried out at the Barcelona Port breaker and dedicated to the development of sea-state retrieval algorithms. An experimental system built for this purpose collected and processed GPS data to automatically generate a times series of the interferometric complex field (ICF). The ICF was analyzed off line and compared to a simple developed model that relates ICF coherence time to the ratio of significant wave height (SWH) and mean wave period (MWP). The analysis using this model showed good consistency between the ICF coherence time and nearby oceanographic buoy data. Based on this result, preliminary conclusions are drawn on the potential of coastal GNSS-R for sea state monitoring using semi-empirical modeling to relate GNSS-R ICF coherence time to SWH. INDEX

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Section: Discussionmentioning

confidence: 99%

Sea state monitoring using coastal GNSS‐R

Soulat

Caparrini

Germain

et al. 2004

Geophysical Research Letters

Self Cite

118

View full text Add to dashboard Cite

show abstract

“…Therefore, potential applications of GPS reflected signals from the sea surface could compensate these defects of conventional radar techniques. Recently, a number of ocean remote sensing applications have been implemented using GPS signals reflected from the ocean surface (Martin-Neira et al 2001;Rius et al 2002;Germain et al 2004;Komjathy et al 2004;Thompson et al 2005;Gleason et al 2005). For example, Martin-Neira et al (2001) showed the height of sea surface Furthermore, GPS in a bistatic radar configuration can receive the power from a reflected signal for a variety of delays and Doppler values in a glistening zone surrounding a nominal specular reflection point (Garrison et al 1998).…”

Section: Gnss Ocean Remote Sensingmentioning

confidence: 99%

GNSS Remote Sensing in the Atmosphere, Oceans, Land and Hydrology

Jin

2011

Geodesy for Planet Earth

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The Global Navigation Satellite System (GNSS) provides a continuous, high precision, global, real-time, and all weather navigation and positioning, which powerfully contributes to all scientific questions related to precise positioning on Earth's surface. Recently, the reflected and refracted signals from GNSS satellites resulted in many new applications in environmental remote sensing. The GNSS refracted signals from Radio Occultation satellites together with ground GNSS observations have produced wide applications in atmospheric remote sensing, including global monitoring of tropospheric water vapour, temperature and pressure, tropopause parameters and ionospheric parameters as well as ionospheric irregularities. The GNSS reflected signals from the ocean and land surface could determine the wave height, wind speed and wind direction of ocean surface and land surface conditions. In this paper, GNSS remote sensing applications in the atmosphere, oceans, land and hydrology are presented as well as recent results. With more and more GNSS satellite constellations in coming years, it is expected more and wider applications in various environment remote sensing.

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“…It is well known, however, that winddriven waves on the ocean surface have an anisotropic distribution, with the principal axis aligned with the wind direction [8]. For this reason, there are expected to be errors in retrievals assuming an isotropic distribution.…”

Section: Problem Descriptionmentioning

confidence: 99%

Anisotropy in ocean scattering of bistatic radar using signals of opportunity

Shah

Garrison

Grant

2011

2011 IEEE International Geoscience and Remote Sensing Symposium

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This paper present experimental results demonstrating the use of "signals of opportunity" from digital communications satellites (XM radio) as bistatic radar for ocean remote sensing. This builds upon the previous work which demonstrated that the shape of the cross-correlation "waveform" of reflected XM radio signals is sensitive to the roughness of the ocean surface. In these new results, we compare this sensitivity between the waveforms produced from the two XM radio satellites, viewed simultaneously at different azimuths, and show that a small discrepancy exists in the mean square slope (MSS) retrievals obtained from each of them. We then investigate the hypothesis that this discrepancy is the result of neglecting anisotropy in the model for the probability density function (PDF) of surface slopes and that this discrepancy might be useful for sensing the wind direction. In order to do so, a two-stage estimation process was applied to data collected on an airborne experiment that recorded the direct line of sight and reflected XM radio signals. In the first step, an isotropic normal distribution was assumed for the PDF and the mean square slope (MSS) was fit to the measured waveform data from each satellite independently. Since the two satellites are located at different azimuths, a difference between the two MSS estimates were observed. The second step involved using a bidirectional normal PDF with MSS constrained to that obtained from the first step, and a value was assumed for the ratio of upwind and crosswind slopes. The direction of the principal axes was varied to minimize the total residuals for both satellites. The results were compared with Chesapeake Lighthouse recordings of the local wind direction.

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The Eddy Experiment: GNSS‐R speculometry for directional sea‐roughness retrieval from low altitude aircraft

Cited by 75 publications

References 18 publications

Sea state monitoring using coastal GNSS‐R

Sea state monitoring using coastal GNSS‐R

GNSS Remote Sensing in the Atmosphere, Oceans, Land and Hydrology

Anisotropy in ocean scattering of bistatic radar using signals of opportunity

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