Search Publications
Statistical distribution of mirror-mode-like structures in the magnetosheaths of unmagnetized planets - Part 2: Venus as observed by the Venus Express spacecraft
Stenberg Wieser, Gabriella; Futaana, Yoshifumi; Mazelle, Christian +7 more
In this series of papers, we present statistical maps of mirror-mode-like (MM) structures in the magnetosheaths of Mars and Venus and calculate the probability of detecting them in spacecraft data. We aim to study and compare them with the same tools and a similar payload at both planets. We consider their dependence on extreme ultraviolet (EUV) s…
Effect of data gaps: comparison of different spectral analysis methods
Mursula, Kalevi; Echim, Marius; Munteanu, Costel +1 more
In this paper we investigate quantitatively the effect of data gaps for four methods of estimating the amplitude spectrum of a time series: fast Fourier transform (FFT), discrete Fourier transform (DFT), Z transform (ZTR) and the Lomb-Scargle algorithm (LST). We devise two tests: the single-large-gap test, which can probe the effect of a single da…
Mirror mode structures near Venus and Comet P/Halley
Zhang, T. L.; Baumjohann, W.; Volwerk, M. +4 more
In this paper, we study where mirror mode structures are generated near unmagnetized solar system bodies (Venus and comet P/Halley measured in situ by Venus Express and Giotto). To estimate the location of the mirror mode source region at Venus, we apply a turbulent diffusion model of mirror mode structures, which has already been successfully tes…
Observation of shocks associated with CMEs in 2007
Zhang, T. L.; Balikhin, M. A.; Taktakishvili, A. +1 more
The interaction of CMEs with the solar wind can lead to the formation of interplanetary shocks. Ions accelerated at these shocks contribute to the solar energetic protons observed in the vicinity of the Earth. Recently a joint analysis of Venus Express (VEX) and STEREO data by Russell et al. (2009) have shown that the formation of strong shocks as…
Exploring planetary magnetic environments using magnetically unclean spacecraft: a systems approach to VEX MAG data analysis
Zhang, T. L.; Balikhin, M. A.; Delva, M. +4 more
In situ measurements of the magnetic field are vital to the study of many fundamental problems in planetary research. Therefore the magnetometer experiment is a key element of the payload of Venus Express. In addition to the interaction of the solar wind with Venus, these measurements are crucial for the study of atmospheric escape and detection o…
Comparison of accelerated ion populations observed upstream of the bow shocks at Venus and Mars
Coates, A. J.; Fedorov, A.; Barabash, S. +12 more
Foreshock ions are compared between Venus and Mars at energies of 0.6~20 keV using the same ion instrument, the Ion Mass Analyser, on board both Venus Express and Mars Express. Venus Express often observes accelerated protons (2~6 times the solar wind energy) that travel away from the Venus bow shock when the spacecraft location is magnetically co…
Occurrence rate of magnetic holes between 0.72 and 1 AU: comparative study of Cluster and VEX data
Zhang, T. L.; Walker, S. N.; Amariutei, O. A.
Localised depressions in the magnetic field magnitude, or magnetic holes, are common features in many regions of solar system plasma. Two distinct mechanisms for their generation have been proposed. The first proposed that the structures are generated locally, close to the point of observation. The alternative has been proposed by Russell et al. (…
Spatial scales of the magnetic ramp at the Venusian bow shock
Zhang, T. L.; Walker, S. N.; Pope, S. A. +1 more
Typically multi-spacecraft missions are ideally suited to the study of shock spatial scales due to the separation of temporal and spatial variations. These missions are not possible at all locations and therefore in-situ multi-spacecraft measurements are not available beyond the Earth. The present paper presents a study of shock spatial scales usi…
Low-frequency magnetic field fluctuations in Venus' solar wind interaction region: Venus Express observations
Zhang, T. L.; Glassmeier, K. -H.; Narita, Y. +4 more
We investigate wave properties of low-frequency magnetic field fluctuations in Venus' solar wind interaction region based on the measurements made on board the Venus Express spacecraft. The orbit geometry is very suitable to investigate the fluctuations in Venus' low-altitude magnetosheath and mid-magnetotail and provides an opportunity for a comp…
On the modeling of planetary plasma environments by a fully kinetic electromagnetic global model HYB-em
Kallio, E.; Pohjola, V.
We have developed a fully kinetic electromagnetic model to study instabilities and waves in planetary plasma environments. In the particle-in-a-cell (PIC) model both ions and electrons are modeled as particles. An important feature of the developed global kinetic model, called HYB-em, compared to other electromagnetic codes is that it is built up …