Comparison of Solar Wind Speeds Using Wavelet Transform and Fourier Analysis in IPS Data

• Published in: Solar physics 2015-09, Vol.290 (9), p.2507-2518
• Main Authors: Aguilar-Rodriguez, E., Mejia-Ambriz, J. C., Jackson, B. V., Buffington, A., Romero-Hernandez, E., Gonzalez-Esparza, J. A., Rodriguez-Martinez, M., Hick, P., Tokumaru, M., Manoharan, P. K.
• Format: Article
• Language: English
• Subjects: Astrophysics and Astroparticles; Atmospheric Sciences; Fluctuation; Fluctuations; Fourier analysis; Heliosphere; Physics; Physics and Astronomy; Power spectra; Radio Heliophysics: Science and Forecasting; Solar flares; Solar physics; Space Exploration and Astronautics; Space Sciences (including Extraterrestrial Physics; Spectra; Terrestrial environments; Time series; Wavelet; Wavelet transforms; Wind speed
• ISSN: 0038-0938; 1573-093X
• DOI: 10.1007/s11207-015-0758-0

The power spectra of intensity fluctuations in interplanetary scintillation (IPS) observations can be used to estimate solar-wind speeds in the inner heliosphere. We obtain and then compare IPS spectra from both wavelet and Fourier analyses for 12 time series of the radio source 3C48; these observations were carried out at Japan’s Solar-Terrestrial Environment Laboratory (STEL) facility, at 327 MHz. We show that wavelet and Fourier analyses yield very similar power spectra. Thus, when fitting a model to spectra to determine solar-wind speeds, both yield comparable results. Although spectra from wavelet and Fourier closely match each other for solar-wind speed purposes, those from the wavelet analysis are slightly cleaner, which is reflected in an apparent level of intensity fluctuations that is enhanced, being ≈ 13 % higher. This is potentially useful for records that show a low signal-to-noise ratio.