Analysis of a 12-Hour Artifact in LF Oscillations of the Magnetic Field of Sunspots According to SDO/HMI Data
Tóm tắt
The properties of the 12-h artifact in the data of the SDO/HMI instrument (Helioseismic and Magnetic Imager) caused by the nonzero radial velocity of the station relative to the Sun are investigated. The study has been carried out with respect to long-period oscillations of the magnetic field of sunspots for different station positions in the Earth’s orbit by the alternative spectral method of singular decomposition of the signal CaterPillarSSA. Features of artifact filtering, both in special positions of the station (at the points of aphelion and perihelion) and at arbitrarily selected orbital points, are considered. It is shown that the 12-h artifact mode can be completely filtered from the time series of the observed variable, not only at these two orbital points (because of the symmetry of the station’s radial velocity with respect to the zero mean here) but also at any others. It is shown that only a 12-h mode is physically justified, while the 24-h harmonic appears only as an artifact in the Fourier decomposition of the amplitude-modulated signal. It is emphasized that the values of the magnetic field measured with SDO/HMI are sensitive only to the station’s radial velocity absolute values with respect to the Sun and do not depend on its direction. It has been noted that the periods of sunspot oscillation as a whole obtained from SDO/HMI data after orbital artifact filtration fit well into the dependence diagram of the period of sunspot oscillations on the value of its magnetic field strength constructed earlier by SOHO/MDIdata.
Tài liệu tham khảo
Astaf’eva, N.M., Wavelet analysis: Basic theory and some applications, Phys.-Usp., 1996, vol. 39, no. 11, pp. 1085–1108.
Chaturantabut, S., Beattie, C., and Gugercin, S., Structure- preserving model reduction for nonlinear port- Hamiltonian systems, 2016. https://arxiv.org/abs/ 1601.00527
Chorley, N., Hnat, B., Nakariakov, V.M., Inglis, A.R., and Bakunina, I.A., Long period oscillations in sunspots, Astron. Astrophys., 2010, vol. 513, id A27.
Couvidat, S., Schou, J., Hoeksema, J.T., et al., Observables processing for the helioseismic and magnetic imager instrument on the Solar Dynamics Observatory, Sol. Phys., 2016, vol. 291, no. 7, pp. 1887–1938.
Dremin, I.M., Ivanov, O.V., and Nechitalo, V.A., Wavelets and their uses, Phys.-Usp., 2001, vol. 44, no. 5, pp. 447–478.
Efremov, V.I., Parfinenko, L.D., and Solov’ev, A.A., Investigation of long-period oscillations of sunspots with ground-based (Pulkovo) and SOHO/MDI data, Sol. Phys., 2010, vol. 267, pp. 279–293.
Efremov, V.I., Parfinenko, L.D., and Solov’ev, A.A., Sunspot oscillations as derived from the SOHO/MDI magnetograms, Cosmic Res., 2012, vol. 50, no. 1, pp. 44–55.
Efremov, V.I., Parfinenko, L.D., Solov’ev, A.A., and Kirichek, E.A., Long-period oscillations of sunspots observed by SOHO/MDI, Sol. Phys., 2014, vol. 289, no. 6, pp. 1983–1998.
Efremov, V.I., Parfinenko, L.D., and Solov’ev, A.A., Ultra low-frequency oscillations of a solar filament observed by the GONG network, Sol. Phys., 2016, vol. 291, no. 11, pp. 3357–3367.
Foullon, C., Verwichte, E., and Nakariakov, V.M., Ultralong- period oscillations in EUV filaments near to eruption: Two-wavelength correlation and seismology, Astrophys. J., 2009, vol. 700, no. 2, pp. 1658–1665.
Golyandina, N., Nekrutkin, V., and Zhigljavsky, A., Analysis of Time Series Structure: SSA and Related Techniques, London: Chapman and Hall/CRC, 2001.
Golyandina, N. and Zhigljavsky, A., Singular Spectrum Analysis for Time Series, Berlin: Springer, 2013. doi 10.1007/978-3-642-34913-3
Gorshkov, V.L., Miller, N.O., and Vorotkov, M.V., Manifestation of solar and geodynamic activity in the dynamics of the Earth’s rotation, Geomagn. Aeron. (Engl. Transl.), 2012, vol. 52, no. 7, pp. 944–952.
Hoeksema, J.T., Liu, Y., Hayashi, K., et al., The Helioseismic and Magnetic Imager (HMI) vector magnetic field pipeline: Overview and performance, Sol. Phys., 2014, vol. 289, no. 9, pp. 3483–3530.
Huang, N., Shen, Z., Long, S.R., et al., The empirical mode decomposition and the Hilbert spectrum for nonlinear and non-stationary time series analysis, R. Soc. London Proc., Ser. A, 1998, vol. 454, pp. 903–995.
Kislyakova, K.G., Zaitsev, V.V., Urpo, S., and Riehokainen, A., Long-period oscillations of the solar microwave emission, Astron. Rep., 2011, vol. 55, no. 3, pp. 275–283.
Kolotkov, D.Y., Smirnova, V.V., Strekalova, P.V., Riehokainen, A., and Nakariakov, V.M., Long-period quasiperiodic oscillations of a small-scale magnetic structure on the Sun, Astron. Astrophys., 2017, vol. 598, id L2.
Kumar, P., Nakariakov, V.M., and Cho, K.-S., X-Ray and EUV observations of simultaneous short and long period oscillations in hot coronal arcade loops, Astrophys. J., 2015, vol. 804, no. 1, id 4.
Kutsenko, A.S. and Abramenko, V.I., Using SDO/HMI magnetograms as a source of the solar mean magnetic field data, Sol. Phys., 2016, vol. 291, no. 6, pp. 1613–1623.
Liu, Y., Norton, A.A., and Scherer, P.H., A note on saturation seen in the MDI/SOHO magnetograms, Sol. Phys., 2007, pp. 185–193.
Liu, Y., Hoeksema, J.T., Scherrer, P.H., et al., Comparison of line-of-sight magnetograms taken by the Solar Dynamics Observatory/Helioseismic and Magnetic Imager and Solar and Heliospheric Observatory/Michelson Doppler Imager, Sol. Phys., 2012, vol. 279, no. 1, pp. 295–316.
Nagovitsyn, Yu.A. and Nagovitsyna, E.Yu., Long-period oscillation processes in sunspot groups (ground-based and exoatmospheric observations), Geomagn. Aeron. (Engl. Transl.), 2011, vol. 51, no. 8, pp. 1049–1053.
Norton, A.A., Pietarila Graham, J., Ulrich, R.K., et al., Spectral line selection for HMI: A comparison of Fe I 6173 Å and Ni I 6768 Å, Sol. Phys., vol. 239, nos. 1–2, pp. 69–91.
Scherrer, P.H., Schou, J., Bush, R.I., et al., The Helioseismic and Magnetic Imager (HMI) investigation for the Solar Dynamics Observatory (SDO), Sol. Phys., 2012, vol. 275, nos. 1–2, pp. 207–227.
Smirnova, V., Riehokainen, A., Ryzhov, V., Zhiltsov, A., and Kallunki, J., Long-period oscillations of millimeter emission above sunspots, Astron. Astrophys., 2011, vol. 534, id A137.
Smirnova, V.V., Efremov, V.I., Parfinenko, L.D., Riehokainen, A., and Solov’ev, A.A., Artifacts of SDO/HMI data and long-period oscillations of sunspots, Astron. Astrophys., 2013a, vol. 554, id A121.
Smirnova, V., Riehokainen, A., Solov’ev, A., Kallunki, J., Zhiltsov, A., and Ryzhov, V., Long quasi-periodic oscillations of sunspots and nearby magnetic structures, Astron. Astrophys., 2013b, vol. 552, id A23S.
Solov’ev, A.A. and Kirichek, E.A., The subphotospheric structure of a sunspot, Astron. Rep., 2009, vol. 53, no. 7, pp. 675–683.
Solov’ev, A.A. and Kirichek, E.A., Basic properties of sunspots: Equilibrium, stability and eigen oscillations, Astrophys. Space Sci., 2014, vol. 352, no. 1, pp. 22–42.
Yuan, D., Nakariakov, V.M., Chorley, N., and Foullon, C., Leakage of long-period oscillations from the chromosphere to the corona, Astron. Astrophys., 2011, vol. 553, id A116.