Saulquin B., Fablet R., Mercier G., Demarcq Hervé, Mangin A., d' Andon O. H. F. (2014). Multiscale event-based mining in geophysical time series : characterization and distribution of significant time-scales in 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, 7 (8), p. 3543-3552. ISSN 1939-1404.
Titre du document
Multiscale event-based mining in geophysical time series : characterization and distribution of significant time-scales in the sea surface temperature anomalies relatively to ENSO periods from 1985 to 2009
Saulquin B., Fablet R., Mercier G., Demarcq Hervé, Mangin A., d' Andon O. H. F.
Source
Ieee Journal of Selected Topics in Applied Earth Observations and Remote Sensing, 2014,
7 (8), p. 3543-3552 ISSN 1939-1404
In this paper, one-dimensional (1-D) geophysical time series are regarded as series of significant time-scale events. We combine a wavelet-based analysis with a Gaussian mixture model to extract characteristic time-scales of 486 144 detected events in the Sea Surface Temperature Anomaly (SSTA) observed from satellite at global scale from 1985 to 2009. We retrieve four low-frequency characteristic time-scales of Nino Southern Oscillation (ENSO) in the 1.5- to 7-year range and show their spatial distribution. High-frequency (HF) SSTA event spatial distribution shows a dependency to the ENSO regimes, pointing 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 of ENSO onto the SSTA. In particular, we observe at global scale a major increase by 11% of the number of SSTA HF events during Nino periods, with a local maximum of 80% in Europe. The methodology is also used to highlight an ENSO-induced frequency shift during the major 1997-2000 ENSO event in the intertropical Pacific. We observe a clear shift from the high frequencies toward the 3.36-year scale with a maximum shift occurring 2 months before the ENSO maximum of energy at 3.36-year scale.
