Speaker
Description
In December 2022, the solar wind virtually disappeared, its density decreased to values of the order of 0.1 cm-3, first at Earth (25/12/2022) and then at Mars (26/12/2022). The impact of this event was dramatic for the two planetary plasma environments. In this study we focus on the spectral and statistical analysis of magnetic field fluctuations recorded by MMS in the magnetosheath of Earth, by MAVEN in the Venusian magnetosheath and solar wind, prior, during and after the vanishing solar wind event. We correlate the results obtained from the analysis of planetary plasma data analysis with similar analyses of solar wind data collected by WIND, for the same time interval. There is a dramatic change in spectral behavior of magnetic field fluctuation with spectral breaks and cross-overs occurring for scales which change with the epoch of the event: prior-, after- , post vanishing of the solar wind. The magnetic fluctuations in the Mars magnetosheath are disordered prior to the solar wind energy drop, but interestingly are much better organized, showing clear signs of Kolmogorov-like turbulence, when the Mars magnetosheath “inflates” due to the disappearance of the solar wind. Intermittency drops also significantly in Mars magnetosheath during the low density event. A similar spectral and statistical behavior of magnetic fluctuations is detected at Earth. The comparison of the response of the two planets helps understanding the impact of sudden solar wind changes on the turbulent coupling with planetary plasma environments.
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