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Published byClifton Shaw Modified over 9 years ago
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New methods on satellite image processing for the instantaneous estimation of velocity fields and their utility in the perspective of reanalysis Antonio Turiel, Jordi Isern-Fontanet, Emilio García-Ladona & Jordi Font Grupo de Oceanografía Física ICM-CMIMA (CSIC) CMIMA
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Summary Context Multiscale techniques Applications to satellite imagery Relevance for data reanalysis
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Context + These data provide global coverage, synopticity and steady rate + Specific tools are needed for: Reanalysis of global scale historical datasets ( 20 years) Operational uses + We have now historical time series of satellite images (Pathfinder, Medspiration project, MeteoSat, etc)
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Multiscale techniques + Link image processing with thermodynamics and turbulence + Do not fix an observation scale (scale invariance) + The resulting sets have a precise, physical meaning + It is well adapted to study geophysical flows: atmosphere and ocean
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Applications to satellite imagery 1.- Identification of physical patterns Based on: Multifractal analysis Multiscale features
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Meteosat IR image Multifractal classification Most Singular Manifold (MSM) Multiscale entropy Local Entropy
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2.- Estimation of QG streamfunctions The MSM is identified with the main current lines We fix the gradient of the streamfunction over the MSM assuming flow advection The streamfunction is reconstructed assuming some statistical invariances
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SST (IFREMER LAS) Most Singular Manifold Most Singular Streamfunction Altimetry (Jason-ENVISAT)
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Altimetry level sets overimposed to MSS
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Excerpt on velocity fields
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3.- Detection of vertical movement Advection dominated Areas (ADA) Convection dominated areas (CDA) Area without any observed structure Meteosat IR in West Africa during strong tropical storms
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Images are « comparable» Original MeteoSat IR image MSM MSS
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Original MeteoSat IR image Images have a very different aspect MSM MSS
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Original image MSS SourcesHyperfrequency Divergence MCC
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Relevance for data reanalysis + Multiscale techniques provide synoptic, global, instantaneous estimates of: Wind fields on atmospheric ADAs, detection of precipitation areas and, eventually, rain intensity Surface currents on ocean ADAs We can evaluate statistical properties of climatic fields
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