Multi-scale event-based mining in geophysical time series: characterization and distribution of significant time-scales into the Sea Surface Temperature anomalies relatively to ENSO periods from 1985 to 2009

Bertrand Saulquin (1) , Ronan Fablet (2) , Grégoire Mercier (3) , Hervé Demarcq (4) , Antoine Mangin (1) , Odile Fanton d'Andon (1)

1 ACRI-ST - Analytic and Computational Research, Inc. - Earth Sciences
2 SC - Département Signal et Communications
3 ITI - Département Image et Traitement Information
4 UMR EME - Ecosystèmes Marins Exploités

In this study 1D geophysical time series are regarded as series of significant time-frequency events. We combine a wavelet-based analysis to a Gaussian Mixture Model to extract characteristic time-scales of 486043 detected into the Sea Surface Temperature Anomaly (SSTA) observed from satellite at global scale from 1985 to 2009. We retrieved four low frequency characteristic time- scales in the 1.5-7 year range, and highlighted their spatial distribution, most of them known as being influenced by the Niño Southern Oscillation (ENSO). The spatial distribution of the high frequency SSTA also showed a dependency to the ENSO regimes. It pointed out that the ENSO signal also involves specific signatures at these time-scales. These fine-scale signatures can hardly be retrieved from global EOF approaches which tend to exhibit uppermost the low frequency influence onto the SSTA of ENSO. We observed particularly a major increase of the high frequency events in the SSTA during Niño periods of 11% at global scale with a local maximum of 80% in Europe. The methodology was also used to highlight an ENSO-induced shift in time-scale during the major 1997-2000 ENSO event in the inter-tropical Pacific. We observed a clear time-scale shift from the high frequencies towards the 3.36 year-scale with a maximum shift observed two months before the maximum of the ENSO event.

Mots clés: data mining; El Nino Southern Oscillation; Gaussian processes; geophysical techniques; mixture models; ocean temperature; time series

Domaines: Traitement du signal et de l'image [eess.SP]; Océanographie

Bertrand Saulquin, Ronan Fablet, Grégoire Mercier, Hervé Demarcq, Antoine Mangin, et al.. Multi-scale event-based mining in geophysical time series: characterization and distribution of significant time-scales into the Sea Surface Temperature anomalies relatively to ENSO periods from 1985 to 2009. IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, 2014, 7 (8), pp.1939-1404. ⟨10.1109/JSTARS.2014.2329921⟩. ⟨hal-01208386⟩