We analyzed three noise storms recorded on 200 – 400 MHz Trieste Callisto radio spectra on 2 July 2012, 8 July 2012, and 16 July 2012 by the Fourier method. We divided intervals of the noise storms into five-minute intervals, and in these intervals we computed the mean Fourier spectra as a function of the wave numbers in the frequency and height-scale spaces. We found that these Fourier spectra, where the spectrum from the quiet-activity interval was subtracted, are power-law spectra. The mean power-law index of these spectra in the range ln(kz)=[1.8,2.9]\documentclass[12pt]{minimal}
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\begin{document}$\ln(k_{z}) = [1.8, 2.9]$\end{document} (where kz\documentclass[12pt]{minimal}
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\begin{document}$k_{z}$\end{document} is the wave number in the height-scale space) is −1.7±0.14\documentclass[12pt]{minimal}
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\begin{document}$-1.7\pm0.14$\end{document}, −1.6±0.14\documentclass[12pt]{minimal}
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\begin{document}$-1.6\pm0.14$\end{document}, and −1.5±0.12\documentclass[12pt]{minimal}
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\begin{document}$-1.5 \pm0.12$\end{document} for the 2 July 2012, the 8 July 2012, and the 16 July 2012 noise storms, respectively. It appears that as the number of Type-I bursts in the studied interval increases, the power-law index becomes closer to −5/3\documentclass[12pt]{minimal}
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\begin{document}$-5/3$\end{document}; this is known as the Kolmogorov spectral index. The power-law index of the noise storms is very similar to that of the narrowband dm-spikes found in our previous studies. Furthermore, we found a break in the power spectra at ln(kz)≈2.9\documentclass[12pt]{minimal}
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\begin{document}$\ln(k_{z}) \approx2.9$\end{document}, and the mean power-law index values above this break are −2.9±0.46\documentclass[12pt]{minimal}
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\begin{document}$-2.9\pm0.46$\end{document}, −3.1±0.65\documentclass[12pt]{minimal}
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\begin{document}$-3.1\pm0.65$\end{document}, and −3.4±0.98\documentclass[12pt]{minimal}
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\begin{document}$-3.4\pm0.98$\end{document}, respectively.
