The spatio-temporal dynamics of the solar photosphere are studied by performinga proper orthogonal decomposition (POD) of line-of-sight velocity fields computed fromhigh-resolution data coming from the SOHO/MDI instrument. Using this technique, we areable to identify and characterize the different dynamical regimes acting in the system. All ofthe POD modes are characterized by two well-separated peaks in the frequency spectra. Inparticular, low-frequency oscillations, with frequencies in the range 20 – 130 μHz, dominatethe most energetic POD modes (excluding solar rotation) and are characterized by spatialpatterns with typical scales of about 3 Mm. Patterns with larger typical scales, of about 10Mm, are dominated by p-mode oscillations at frequencies of about 3000 μHz. The p-modeproperties found by POD are in agreement with those obtained with the classical Fourieranalysis. The spatial properties of high-energy POD modes suggest the presence of a strongcoupling between low-frequency modes and turbulent convection.

Spatio-Temporal Analysis of Photospheric Turbulent Velocity Fields Using the Proper Orthogonal Decomposition

CARBONE, Vincenzo;LEPRETI, Fabio;PRIMAVERA, Leonardo;VELTRI, Pierluigi
2008-01-01

Abstract

The spatio-temporal dynamics of the solar photosphere are studied by performinga proper orthogonal decomposition (POD) of line-of-sight velocity fields computed fromhigh-resolution data coming from the SOHO/MDI instrument. Using this technique, we areable to identify and characterize the different dynamical regimes acting in the system. All ofthe POD modes are characterized by two well-separated peaks in the frequency spectra. Inparticular, low-frequency oscillations, with frequencies in the range 20 – 130 μHz, dominatethe most energetic POD modes (excluding solar rotation) and are characterized by spatialpatterns with typical scales of about 3 Mm. Patterns with larger typical scales, of about 10Mm, are dominated by p-mode oscillations at frequencies of about 3000 μHz. The p-modeproperties found by POD are in agreement with those obtained with the classical Fourieranalysis. The spatial properties of high-energy POD modes suggest the presence of a strongcoupling between low-frequency modes and turbulent convection.
2008
Velocity fields ; Granulation ; Oscillations ; Solar: turbulence
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.11770/143820
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