A Spaceborne Radar for Directional Wave Spectrum Estimation: First Performance Simulations

Tison, C.; Carayon, G.; Lambin, J.; Castillan, Patrick; Souyris, J.-C.; Hauser, Danièle

doi:10.1109/igarss.2008.4778865

Cited by 5 publications

(4 citation statements)

References 8 publications

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“…In the experiments we did not consider all types of data available for regional modeling. In particular, directional spectra (with a coarser resolution and larger uncertainties) can be obtained from high-frequency radars (Graber and Heron 1997;Hisaki 2005) and spaceborne (Tison et al 2008;Ren et al 2010) platforms. Simplifying assumptions have been also made in configuring WAM: the background currents (;0.2-0.4 m s 21 ) were assumed to be negligible in comparison with the wave velocities (;5-10 m s 21 ) of the major spectral peak and stationary conditions at the open boundaries were specified due to relatively short period of model integration.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

Adjoint-Free Variational Data Assimilation into a Regional Wave Model

Panteleev

Yaremchuk

Rogers

2015

Journal of Atmospheric and Oceanic Technology

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A variational data assimilation algorithm is developed for the ocean wave prediction model [Wave Model (WAM)]. The algorithm employs the adjoint-free technique and was tested in a series of data assimilation experiments with synthetic observations in the Chukchi Sea region from various platforms. The types of considered observations are directional spectra estimated from point measurements by stationary buoys, significant wave height (SWH) observations by coastal high-frequency radars (HFRs) within a geographic sector, and SWH from satellite altimeter along a geographic track. Numerical experiments demonstrate computational feasibility and robustness of the adjoint-free variational algorithm with the regional configuration of WAM. The largest improvement of the model forecast skill is provided by assimilating HFR data (the most numerous among the considered types). Assimilating observations of the wave spectrum from a moored platform provides only moderate improvement of the skill, which disappears after 3 h of running WAM in the forecast mode, whereas skill improvement provided by HFRs is shown to persist up to 9 h. Spaceborne observations, being the least numerous, do not have a significant impact on the forecast skill but appear to have a noticeable effect when assimilated in combination with other types of data. In particular, when spectral data from a single mooring are used, the satellite data are found to be the most beneficial as a supplemental data type, suggesting the importance of spatial coverage of the domain by observations.

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Section: Conclusion and Discussionmentioning

confidence: 99%

Adjoint-Free Variational Data Assimilation into a Regional Wave Model

Panteleev

Yaremchuk

Rogers

2015

Journal of Atmospheric and Oceanic Technology

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“…The validity of the principle to derive the spectra of ocean waves from this concept has been demonstrated several times using airborne systems developed at NASA (ROWS system, [2]) and in France (RESSAC radar, [3]). Simulation approaches have been used first to assess the feasibility of the concept [5] and are presently extended and used to perform detailed analysis of the system performance [7]. The retrieval of the directional spectrum of surface waves is based on the spectral analysis of the radar backscatter modulations in each look direction, providing a modulation spectrum versus wave number of the ocean waves.…”

Section: Figure 1: Geometry Of Observation Of the Swim Instrumentmentioning

confidence: 99%

“…The modulation spectrum is a random variable. Thus, in [7], the expression of the theoretical standard deviation σ has been derived. This enables to define the 3σ margins around the mean value.…”

Section: Simulation Of Performance Of Wave Spectra Estimatesmentioning

confidence: 99%

Measuring Ocean Waves From Space: Objectives and Characteristics of the China-France Oceanography SATellite (CFOSAT)

Hauser

Tison

Lefèvre

et al. 2010

29th International Conference on Ocean, Offshore and Arctic Engineering: Volume 4

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The Chinese and French Space Agencies are jointly preparing a satellite mission devoted to the monitoring of the ocean surface and related science and applications. This is the so-called “China France Oceanography SATellite” (CFOSAT), to be launched around 2013. This mission will provide simultaneous and collocated observations of wind at the ocean surface and spectral properties of surface ocean waves using two scatterometers, both in Ku-Band: SWIM for measurements of directional wave spectra and SCAT for wind vector measurements. The SWIM instrument will use a real aperture observation technique so as to avoid limitations encountered with SAR systems. This paper describes the main objectives and characteristics of the mission with a focus on the SWIM instrument designed and developed under French responsibility to measure directional spectra of ocean waves.

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“…They made use of the wave model (PM, Jonswap, Durden-Vesecky) to generate the input wave spectrum of simulation system and compared the simulation results in terms of modulation spectrum. (Hauser, 2001;Tison et al, 2008).…”

Section: Introductionmentioning

confidence: 98%

Satellite-based RAR performance simulation for measuring directional ocean wave spectrum based on SAR inversion spectrum

Ren

Mao²,

Huang³

et al. 2010

Acta Oceanol. Sin.

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Some missions have been carried out to measure wave directional spectrum by synthetic aperture radar (SAR) and airborne real aperture radar (RAR) at a low incidence. Both them have their own advantages and limitations. Scientists hope that SAR and satellite-based RAR can complement each other for the research on wave properties in the future. For this study, the authors aim to simulate the satellite-based RAR system to validate performance for measuring the directional wave spectrum. The principal measurements are introduced and the simulation methods based on the one developed by Hauser are adopted and slightly modified. To enhance the authenticity of input spectrum and the wave spectrum measuring consistency for SAR and satellite-based RAR, the wave height spectrum inversed from Envisat ASAR data by cross spectrum technology is used as the input spectrum of the simulation system. In the process of simulation, the sea surface, backscattering signal, modulation spectrum and the estimated wave height spectrum are simulated in each look direction. Directional wave spectrum are measured based on the simulated observations from 0 • to 360 • . From the estimated wave spectrum, it has an 180 • ambiguity like SAR, but it has no special high wave number cut off in all the direction. Finally, the estimated spectrum is compared with the input one in terms of the dominant wave wavelength, direction and SWH and the results are promising. The simulation shows that satellite-based RAR should be capable of measuring the directional wave properties. Moreover, it indicates satellite-based RAR basically can measure waves that SAR can measure.

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A Spaceborne Radar for Directional Wave Spectrum Estimation: First Performance Simulations

Cited by 5 publications

References 8 publications

Adjoint-Free Variational Data Assimilation into a Regional Wave Model

Adjoint-Free Variational Data Assimilation into a Regional Wave Model

Measuring Ocean Waves From Space: Objectives and Characteristics of the China-France Oceanography SATellite (CFOSAT)

Satellite-based RAR performance simulation for measuring directional ocean wave spectrum based on SAR inversion spectrum

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