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Article Dans Une Revue IEEE Transactions on Geoscience and Remote Sensing Année : 2022

Improving the Estimation of the Wavenumber Spectra From Altimeter Observations

Résumé

Satellite altimeters provide sea-level measurements along satellite track. A mean profile based on the measurementsaveraged over a time period is then subtracted to estimatethe sea-level anomaly (SLA). In the spectral domain, SLA ischaracterized by a power spectral density (PSD) whose slopein a log–log scale is a parameter of great interest for ocean monitoring. Estimation of this spectral slope is usually done through a cumulated periodogram using a large number of signal samples. The location and dates of the data induce the spatial and temporal resolution of the slope estimates. To improve this resolution, this article studies a new parametric method based on an autoregressive model combined with a warping of the frequency scale (denoted as ARWARP). This ARWARP model provides a PSD estimate, with a lower variance than the classical Fourier-based ones and is reliable in the case of a small sample number. To give a reference in the performance of the SLA slope estimation, the corresponding Cramér–Rao bound is derived. Then, rather than performing linear regression on the spectral estimates, a new estimator of the slope is suggested, based on a model fitting of the PSD. A statistical validation is proposed on simulated SLA signals, showing the performance of slope estimation using this ARWARP spectral estimator, compared toclassical Fourier-based methods. Application to Sentinel-3 real data highlights the main advantage of the ARWARP model,making possible SLA slope estimation on a short signal segment, i.e., with a high spatial and/or temporal resolution.
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Dates et versions

hal-03617061 , version 1 (23-03-2022)

Identifiants

Citer

Corinne Mailhes, Olivier Besson, Amandine Guillot, Sophie Le Gac. Improving the Estimation of the Wavenumber Spectra From Altimeter Observations. IEEE Transactions on Geoscience and Remote Sensing, 2022, 60 (4201810), pp.0. ⟨10.1109/TGRS.2021.3071802⟩. ⟨hal-03617061⟩
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