Spatio-Temporal Analysis of Photospheric Turbulent Velocity Fields Using the Proper Orthogonal Decomposition |
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Authors: | A Vecchio V Carbone F Lepreti L Primavera L Sorriso-Valvo T Straus P Veltri |
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Institution: | 1. Dipartimento di Fisica, Università della Calabria, Rende (CS), Italy 2. LICRYL, INFM/CNR, Ponte P. Bucci 31/C, 87036, Rende (CS), Italy 3. INAF—Osservatorio Astronomico di Capodimonte, Napoli, Italy
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Abstract: | The spatio-temporal dynamics of the solar photosphere are studied by performing a proper orthogonal decomposition (POD) of line-of-sight velocity fields computed from high-resolution data coming from the SOHO/MDI instrument. Using this technique, we are able to identify and characterize the different dynamical regimes acting in the system. All of the POD modes are characterized by two well-separated peaks in the frequency spectra. In particular, low-frequency oscillations, with frequencies in the range 20?–?130 μHz, dominate the most energetic POD modes (excluding solar rotation) and are characterized by spatial patterns with typical scales of about 3 Mm. Patterns with larger typical scales, of about 10 Mm, are dominated by p-mode oscillations at frequencies of about 3000 μHz. The p-mode properties found by POD are in agreement with those obtained with the classical Fourier analysis. The spatial properties of high-energy POD modes suggest the presence of a strong coupling between low-frequency modes and turbulent convection. |
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