Earth atmospheric loss through the plasma mantle and its dependence on solar wind parameters

International audienceAtmospheric loss and ion outflow play an important role in the magnetospheric dynamics and in the evolution of the atmosphere on geological timescales-an evolution which is also dependent on the solar activity. In this paper, we investigate the total O + outflow [ s −1 ] through the plasma mantle and its dependency on several solar wind parameters. The oxygen ion data come from the CODIF instrument on board the spacecraft Cluster 4 and solar wind data from the OMNIWeb database for a period of 5 years (2001-2005). We study the distribution of the dynamic pressure and the interplanetary magnetic field for time periods with available O + observations in the plasma mantle. We then divided the data into suitably sized intervals. Additionally, we analyse the extreme ultraviolet radiation (EUV) data from the TIMED mission. We estimate the O + escape rate [ions/s] as a function of the solar wind dynamic pressure, the interplanetary magnetic field (IMF) and EUV. Our analysis shows that the O + escape rate in the plasma mantle increases with increased solar wind dynamic pressure. Consistently, it was found that the southward IMF also plays an important role in the O + escape rate in contrast to the EUV flux which does not have a significant influence for the plasma mantle region. Finally, the relation between the O + escape rate and the solar wind energy transferred into the magnetosphere shows a nonlinear response. The O + escape rate starts increasing with an energy input of approximately 10 11 W