Removing Intra-1-Hz Covariant Error to Improve Altimetric Profiles of σ⁰ and Sea Surface Height

Quartly, GD, Smith, WHF and Passaro, M 2019 Removing Intra-1-Hz Covariant Error to Improve Altimetric Profiles of σ⁰ and Sea Surface Height. IEEE Transactions on Geoscience and Remote Sensing, 57 (6). 3741-3752.

Intra1Hz_AuthVers (2).pdf - Accepted Version
Available under License All Rights Reserved.

Download (1MB) | Preview
Official URL:


Waveform retracking is the process by which a simple mathematical model is fitted to altimeter returns. Over the ocean, the waveform location, the amplitude, and the shape can be fitted by models with 3-5 free parameters, which may, in turn, be linked to geophysical properties of the surface of interest--principally sea surface height (SSH), wave height, and normalized backscatter strength (σ⁰, related to wind speed). However, random multiplicative noise, which is due to the summation of power from multiple differently orientated surfaces, produces errors in the estimation of these model parameters. Examination of the correlations among parameters estimated for each waveform leads to simple empirical corrections that reduce the waveform-to-waveform noise in geophysical estimates, resulting in smoother (and more realistic) along-track profiles of σ⁰ and SSH. These adjustments are fundamentally dependent upon the waveform model and retracker implemented, but when applied show improved agreement between near-simultaneous measurements from different altimeter missions. The effectiveness of these empirical adjustments is documented fully for MLE-4 retracking of the Jason-3 altimeter, with a reduction in the 1-s variance of σ⁰ by 97%. However, the ideas are applicable and beneficial for data from other altimeters, with small improvements in σ⁰ for MLE-3 and for AltiKa at Ka-band, while reductions in range variance of ~40% are noted for most retrackers evaluated.

Item Type: Publication - Article
Additional Information. Not used in RCUK Gateway to Research.: © © 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works
Divisions: Plymouth Marine Laboratory > Science Areas > Earth Observation Science and Applications
Depositing User: Kim Hockley
Date made live: 28 Jan 2019 14:07
Last Modified: 25 Apr 2020 09:59

Actions (login required)

View Item View Item