Articles | Volume 34, issue 4
https://doi.org/10.5194/angeo-34-437-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
https://doi.org/10.5194/angeo-34-437-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
Effect of data gaps: comparison of different spectral analysis methods
Institute of Space Science, Magurele, Romania
Astronomy and Space Physics Research Unit, University of Oulu, Oulu, Finland
Department of Physics, University of Bucharest, Magurele, Romania
Catalin Negrea
Institute of Space Science, Magurele, Romania
Cooperative Institute for Research in Environmental Sciences, Univ. of Colorado, Boulder, Colorado, USA
Space Weather Prediction Center, NOAA, Boulder, Colorado, USA
Marius Echim
Institute of Space Science, Magurele, Romania
Belgian Institute of Space Aeronomy, Brussels, Belgium
Kalevi Mursula
Astronomy and Space Physics Research Unit, University of Oulu, Oulu, Finland
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We study how well the F10.7 and F30 solar radio fluxes represent solar energy input in the thermosphere during the last 60 years. We found that increased saturation of radio fluxes at recent solar minima leads to an overestimation of solar energy, which change the relation between thermospheric parameters and F10.7, but this is not an issue for F30 because of a relative increase of F30 with respect to F10.7. This explains why F30 has been found to represent solar energy better than F10.7.
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Ann. Geophys., 36, 1521–1535, https://doi.org/10.5194/angeo-36-1521-2018, https://doi.org/10.5194/angeo-36-1521-2018, 2018
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The frontal region of Earth's magnetic shield, the magnetopause, is very often impacted by high-speed jets of solar origin that can trigger multiple geophysical effects. Our study brings novel results that contribute to understanding the dynamics of such structures. We performed advanced simulations and demonstrate the formation of a peculiar particle distribution of the energy (the crescent-shaped electron distribution) at the edges of plasma jets interacting with the magnetopause.
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We investigate the effect of data gaps for various methods of estimating the amplitude spectrum of a time series. We probe the effects of a single data gap of varying size and of numerous small gaps distributed within the time series. We use synthetic data sets and magnetic field measurements from the Venus Express spacecraft. For multiple gaps and turbulent magnetic data, we show that some advanced methods overestimate the high frequencies, while FFT slightly underestimates them.
We investigate the effect of data gaps for various methods of estimating the amplitude spectrum...