Ion-dispersion and rapid electron fluctuations in the cusp: a case study

Abstract

Abstract. We present results from co-ordinated measurements with the low altitude REIMEI satellite and the ESR (EISCAT Svalbard Radar), together with other ground-based instruments carried out in February 2006. The results mainly relate to the dayside cusp where clear signatures of so-called ion-dispersion are seen in the satellite data. The cusp iondispersion is important for helping to understand the temporal and spatial structure of magnetopause reconnection. Whenever a satellite crosses boundaries of flux tubes or convection cells, cusp structures such as ion-dispersion will always be encountered. In our case we observed 3 distinct steps in the ion energy, but it includes at least 2 more steps as well, which we interpret as temporal features in relation to pulsed reconnection at the magnetopause. In addition, fast variations of the electron flux and energy occurring during these events have been studied in detail. The variations of the electron population, if interpreted as structures crossed by the REIMEI satellite, would map near the magnetopause to similar features as observed previously with the Cluster satellites. These were explained as Alfvén waves originating from an X-line of magnetic reconnection.

A New Technique for Estimating the Lifetime of Bursts of Electron Precipitation From Sounding Rocket Measurements

“…Applying this technique to the RENU2 rocket data showed that some of the PMAFs had very short lifetimes, on the order of 100 ms and that some time variations were probably occurring within the PMAFs. These precipitation bursts are even shorter than those reported on by Pfaff et al (1998) and Lunde et al (2008).…”

“…Another interesting question that is addressed from the RENU2 data is the lifetime of PMAF precipitation. While short-lived electron bursts in the cusp have been inferred from other satellite data (Lunde et al, 2008;Pfaff et al, 1998), the combination of data obtained on this flight provides the chance to better quantify this.…”