Improving Data Quality for the Australian High Frequency Ocean Radar Network through Real-Time and Delayed-Mode Quality-Control Procedures

Simone Cosoli,Badema Grcic,Yasha Hetzel,Stuart De Vos

doi:10.3390/rs10091476

Simone Cosoli, Badema Grcic + Show 2 more

Open Access

https://doi.org/10.3390/rs10091476

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Journal: Remote sensing	Publication Date: Sep 16, 2018
Citations: 18	License type: CC BY 4.0

Affiliation: Ocean Institute, University of Western Australia

Abstract

Quality-control procedures and their impact on data quality are described for the High-Frequency Ocean Radar (HFR) network in Australia, in particular for the commercial phased-array (WERA) HFR type. Threshold-based quality-control procedures were used to obtain radial velocity and signal-to-noise ratio (SNR), however, values were set through quantitative analyses with independent measurements available within the HFR coverage, when available, or from long-term data statistics. An artifact removal procedure was also applied to the spatial distribution of SNR for the first-order Bragg peaks, under the assumption the SNR is a valid proxy for radial velocity quality and that SNR decays with range from the receiver. The proposed iterative procedure was specially designed to remove anomalous observations associated with strong SNR peaks caused by the 50 Hz sources. The procedure iteratively fits a polynomial along the radial beam (1-D case) or a surface (2-D case) to the SNR associated with the radial velocity. Observations that exceed a detection threshold were then identified and flagged. After removing suspect data, new iterations were run with updated detection thresholds until no additional spikes were found or a maximum number of iterations was reached.

Highlights

The Australian Ocean Radar facility at the University of Western Australia is part of the Integrated Marine Observing System (IMOS), a national collaborative research infrastructure tasked with collection and dissemination of ocean data
This paper focuses on the quality-control (QC) procedures that have been implemented for the phased array systems in Australia and are applied operationally on both the near real-time (NRT) and delayed-mode (DM) products
The Australian Ocean Radar network includes the compact cross-loop systems direction-finding High-Frequency Radar (HFR) system provided by Codar Ocean Sensors (US) and the WERA phased-array HFR systems manufactured by Helzel MessTechnik (Germany)

Summary

Introduction

The Australian Ocean Radar facility at the University of Western Australia is part of the Integrated Marine Observing System (IMOS), a national collaborative research infrastructure tasked with collection and dissemination of ocean data. Commercial direction-finding (SeaSonde) and phased-array (WERA) HFR systems, provided respectively by Codar Ocean Sensors (COS) and Helzel MessTechnik, are in operation in the Rottnest Shelf and Turquoise Coast (Western Australia, WA; Figure 1), Coffs Harbour and Newcastle (New South Wales, NSW, Australia), and the South Australian Gulf regions (SAG). Each HFR node is configured primarily to sample ocean currents with a maximum range of over 200 km; at selected locations where the phased-arrays systems are installed, waves and winds can be obtained. The main focus is on radial currents and surface current maps, but some of the proposed methodologies have the potential to be applied to wind and wave data available from the phased-array systems

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