Study of ultra low frequency waves in the magnetosheath of Venus
A study of low frequency plasma waves in unmagnetized Solar System bodies
| Full text | |
| Author(s): |
Total Authors: 5
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| Affiliation: | [1] Natl Inst Space Res INPE, Sao Jose Dos Campos - Brazil
[2] Max Planck Inst Solar Syst Res, Gottingen - Germany
[3] Fed Univ Jatai, Jatai - Brazil
[4] Austrian Acad Sci, Space Res Inst, Graz - Austria
Total Affiliations: 4
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| Document type: | Journal article |
| Source: | Planetary and Space Science; v. 180, JAN 2020. |
| Web of Science Citations: | 1 |
| Abstract | |
A study of the correlation length of ultra-low frequency (ULF) waves around Venus was developed using electron density and magnetic field data obtained from the Analyzer of Space Plasmas and Energetic Atoms (ASPERA-4) and magnetometer (MAG), respectively, on board of the mission Venus Express (VEX). The analysis was conducted using the whole interval of the mission (2006-2014). The correlation scales have been calculated by the correlation length parameter that is a characteristic distance over which fluctuations in a variable are correlated. We limited the study to the frequency range from 8 to 50 mHz because previous studies have shown that ULF waves produced in the foreshock have the highest power in this range. In this study the correlation length was calculated by an exponential fit employed to the auto-correlation curve. The auto-correlation function was calculated lagged by a time between 0 and 60 s and sliding a window with 120s across the data. This analysis has been also extended to correlation length determinations in spatial scale. In order to obtain the correlation length in a spatial domain, the temporal correlation length must be multiplied by the solar wind velocity. Here, the ASPERA-4/IMA (Ion Mass Analyzer) velocity data was used. It was found that the dominant correlation length in temporal scale varies from 9 to 14 s in electron density and between 7.5 and 11 s in the magnetic field. In spatial scale, correlation length varies between 2.8 x 10(3) and 5 x 10(3) km in electron density data, and between 1.7 x 10(3) -4X10(3) km for the total magnetic field data value in this frequency window. Fluctuations in the magnetosheath and in the MPB may be correlated with fluctuations at the ionosphere, since correlation lengths in those regions are larger than the size of these regions, indicating that local resonant effect of wave trains at the ionopause may enhance the atmospheric ion escape at Venus. Our results also show that pickup heavy ions can interact with discontinuities in the magnetosheath of Venus and can destroy ULF wave trains during periods of low solar wind pressure. The results obtained here are compared with a similar previous analysis in the Mars environment. (AU) | |
| FAPESP's process: | 17/00516-8 - A study on electron oscillations in the magnetosheath of mars with mars express observations |
| Grantee: | Adriane Marques de Souza Franco |
| Support Opportunities: | Scholarships abroad - Research Internship - Doctorate |
| FAPESP's process: | 16/10794-2 - Study on Electron Oscilations in the Magnetosheath of Mars |
| Grantee: | Adriane Marques de Souza Franco |
| Support Opportunities: | Scholarships in Brazil - Doctorate |
| FAPESP's process: | 18/21657-1 - Study of Jupiter magnetospheric auroral radio activity variability |
| Grantee: | Ezequiel Echer |
| Support Opportunities: | Regular Research Grants |