Wave anomaly detection in wave measurements

View More View Less
  • 1 Department of Infrastructure Engineering, University of Melbourne, Victoria, Australia
  • 2 Department of Infrastructure Engineering, University of Melbourne, Victoria, Australia, Laboratory for Regional Oceanography and Numerical Modeling, Qingdao National Laboratory for Marine Science and Technology, China
  • 3 Department of Infrastructure Engineering, University of Melbourne, Victoria, Australia
  • 4 Laboratory of Ocean and Atmosphere Studies (LOA), Earth Observation and Geoinformatics Division, National Institute for Space Research (OBT/INPE), São José dos Campos, São Paulo, Brazil
  • 5 Institute of Energy and Environment, University of São Paulo, São Paulo, Brazil
  • 6 Laboratory of Ocean and Atmosphere Studies (LOA), Earth Observation and Geoinformatics Division, National Institute for Space Research (OBT/INPE), São José dos Campos, São Paulo, Brazil
© Get Permissions
Restricted access

Abstract

Quality control measures for ocean waves observations are necessary to give confidence of their accuracy. It is common practice to detect anomalies or outliers in surface displacement observations by applying a standard deviation threshold. Besides being a purely statistical method, this quality control procedure is likely to flag extreme wave events erroneously, thereby impacting higher order descriptions of the wave field. In this paper we extend the use of the statistical phase-space threshold, an established outlier detection method in the field of turbulence, to detect anomalies in a wave record. We show that a wave record in phase-space (here defined as a diagram of displacement against acceleration) can be enclosed by a predictable ellipse where the major and minor axis are defined by the spectral properties of the wave field. By using the parameterized ellipse in phase-space as a threshold to identify wave anomalies, this is a semi-physical filtering method. Wave buoy data obtained from a mooring deployed near King George Island, Antarctica (as part of the Antarctic Modeling Observation System, ATMOS) and laser altimeter data obtained at the Northwest Shelf of Australia were used to demonstrate the functioning of the filtering methodology in identifying wave anomalies. Synthetic data obtained using a high-order spectral model is used to identify how extreme waves are positioned in phase-space.

Corresponding author: Joey Voermans, jvoermans@unimelb.edu.au

Abstract

Quality control measures for ocean waves observations are necessary to give confidence of their accuracy. It is common practice to detect anomalies or outliers in surface displacement observations by applying a standard deviation threshold. Besides being a purely statistical method, this quality control procedure is likely to flag extreme wave events erroneously, thereby impacting higher order descriptions of the wave field. In this paper we extend the use of the statistical phase-space threshold, an established outlier detection method in the field of turbulence, to detect anomalies in a wave record. We show that a wave record in phase-space (here defined as a diagram of displacement against acceleration) can be enclosed by a predictable ellipse where the major and minor axis are defined by the spectral properties of the wave field. By using the parameterized ellipse in phase-space as a threshold to identify wave anomalies, this is a semi-physical filtering method. Wave buoy data obtained from a mooring deployed near King George Island, Antarctica (as part of the Antarctic Modeling Observation System, ATMOS) and laser altimeter data obtained at the Northwest Shelf of Australia were used to demonstrate the functioning of the filtering methodology in identifying wave anomalies. Synthetic data obtained using a high-order spectral model is used to identify how extreme waves are positioned in phase-space.

Corresponding author: Joey Voermans, jvoermans@unimelb.edu.au
Save