Swarm Langmuir Probe measurements : analysis and characterization of the data quality

<p>Swarm is a three-satellite constellation mission launched by ESA in 2013 flying at an altitude of about 510 km for Swarm Bravo, and 460 km for Alpha and Charlie. The three satellites carry identical instruments continuously collecting ground-breaking data on the various components of the magnetic field and on the near-Earth environment and their dynamics. The Electric Field Instrument (EFI)  is composed by the Thermal Ion Imager (TII) and two Langmuir Probes (LPs) which measure the electron density, temperature and spacecraft potential with the cadence of 2Hz. The scope of this work is to provide an updated status of the L1B data derived from LP measurements, describing some of anomalies affecting the data products as well the outcomes of recent investigations aiming at further improving the science quality of the LP-based Swarm data.</p>

The ultra low frequency electromagnetic radiation observed in the topside ionosphere above boundaries of tectonic plates

In this paper we present results of a comparison between ultra low frequency (ULF) electromagnetic (EM) radiation, recorded by an electric field instrument onboard the satellite detection of electromagnetic emissions transmitted from earthquake regions in the topside ionosphere, and the seismicity of regions with high and low seismic activity. In particular, we evaluated the energy variations of the ULF Ezelectric field component during a period of four years (2006-2009), in order to examine the possible relation of ULF EM radiation with seismogenic regions located in Central America, Indonesia, the Eastern Mediterranean Basin and Greece. As a tool for evaluating the ULF Ez energy variations we used singular spectrum analysis techniques. The results of our analysis clearly show a significant increase of the ULF EM energy emitted from regions of highest seismic activity at the boundaries tectonic plates. Furthermore, we found that higher electromagnetic radiation was detected in a region above the northern- western Greek Arc (R1) than above the adjacent region including Athens and its urban area. We interpret these results of the present study as suggesting that: i) the seismogenic regions at the boundary of tectonic plates radiate ULF EM emissions observed by satellites in the topside ionosphere; and ii) that this EM radiation is not only related with the occurrence time of great (M≥5) earthquakes, but it is often present in intermediate times and it appears as a quasi-permanent phenomenon.

In-flight calibration of double-probe electric field measurements on Cluster

Double-probe electric field instrument with long wire booms is one of the most popular techniques for in situ measurement of electric fields in plasmas on spinning spacecraft platforms, which have been employed on a large number of space missions. Here we present an overview of the calibration procedure used for the Electric Field and Wave (EFW) instrument on Cluster, which involves spin fits of the data and correction of several offsets. We also describe the procedure for the offset determination and present results for the long-term evolution of the offsets.

Exploring the role of ionospheric drivers during the extreme solar minimum of 2008

During the recent solar minimum, solar activity reached the lowest levels observed during the space age, resulting in a contracted atmosphere. This extremely low solar activity provides an unprecedented opportunity to understand the variability of the Earth's ambient ionosphere. The average E × B drifts measured by the Vector Electric Field Instrument (VEFI) on the Communications/Navigation Outage Forecasting System (C/NOFS) satellite during this period are found to have several differences from the expected climatology based on previous solar minima, including downward drifts in the early afternoon and a weak to non-existent pre-reversal enhancement. Using SAMI2 (Sami2 is Another Model of the Ionosphere) as a computational engine, we investigate the effects of these electrodynamical changes as well as the contraction of the thermosphere and reduced EUV ionization on the ionosphere. The sensitivity of the simulations to wind models is also discussed. These modeled ionospheres are compared to the C/NOFS average topside ion density and composition and Formosa Satellite-3/Constellation Observing System for Meteorology, Ionosphere, and Climate average NmF2 and hmF2. In all cases, incorporating the VEFI drift data significantly improves the model results when compared to both the C/NOFS density data and the F3/C GOX data. Changing the MSIS and EUVAC models produced changes in magnitude, but not morphology with respect to local time. The choice of wind model modulates the resulting topside density and composition, but only the use of the VEFI E × B drifts produces the observed post-sunset drop in the F peak.