Gábor Facskó

Wigner Fizikai Kutatóközpont · Space Physics and Space Technology

We compare the predictions of the GUMICS$-$4 global magnetohydrodynamic model for the interaction of the solar wind with the Earth's magnetosphere with Cluster~SC3 measurements for over one year, from January 29, 2002, to February 2, 2003. In particular, we compare model predictions with the north/south component of the magnetic field ($B_{z}$) see...

Gas pipelines, transmission lines, overhead wires, transformers, GNSS navigation, and telecommunication systems are part of critical infrastructure. Industry, transportation, service operations, farming, and everyday life highly depend on this infrastructure. However, these systems are very sensitive to solar activity. Therefore, all activities abo...

Investigation of small-size two-dimensional (2D) targets is a difficult task; it requires—among others—arrays with a high horizontal resolution. According to numerical calculations and quasi-field studies besides the Dipole, the γ11n arrays, a special group of quasi null arrays were expected to be appropriate for this aim. Test field measurements w...

Dayside transients, such as hot flow anomalies, foreshock bubbles, magnetosheath jets, flux transfer events, and surface waves, are frequently observed upstream from the bow shock, in the magnetosheath, and at the magnetopause. They play a significant role in the solar wind-magnetosphere-ionosphere coupling. Foreshock transient phenomena, associate...

The Earth's magnetopause is highly variable in location and shape and is modulated by solar wind conditions. On 8 March 2012, the ARTEMIS probes were located near the tail current sheet when an interplanetary shock arrived under northward interplanetary magnetic field conditions and recorded an abrupt tail compression at ∼(‐60, 0, ‐5) RE in Geocent...

This study reports observations of energetic ions upstream of the Earth's quasi-parallel bow shock by Cluster at times when interspacecraft separation distances were large. We analyze two individual upstream ion events during high solar wind velocity conditions to compare the spatial evolution of partial energetic ion densities in front of the Eart...

We use a global magnetohydrodynamics simulation to analyze transient magnetic reconnection processes at the magnetopause. The solar wind conditions have been kept constant and an interplanetary magnetic field (IMF) with large duskward BY and southward BZ components has been imposed. Five flux transfer events (FTEs) with clear bipolar magnetic field...

Position, width and fragmentation level of fracture zones and position, significance and characteristic distance of fractures were aimed to determine in a carbonate aquifer. These are fundamental parameters, e.g. in hydrogeological modelling of aquifers, due to their role in subsurface water movements. The description of small scale fracture system...

The ultimate formation mechanism of the substorm current wedge (SCW) remains to date unclear. In this study, we investigate its relationship to plasma flows at substorm onset and throughout the following expansion phase. We revisit the case of 8 September 2002, which has been defined as “one of the best textbook examples of a substorm” because of i...

The response of the Earth's magnetosphere to changing solar wind conditions are studied with a 3D Magnetohydrodynamic (MHD) model. One full year (155 Cluster orbits) of the Earth's magnetosphere is simulated using Grand Unified Magnetosphere Ionosphere Coupling simulation (GUMICS-4) magnetohydrodynamic code. Real solar wind measurements are given t...

The response of the Earth's magnetosphere to changing solar wind conditions are studied with a 3D Magnetohydrodynamic (MHD) model. One full year (155 Cluster orbits) of the Earth's magnetosphere is simulated using Grand Unified Magnetosphere Ionosphere Coupling simulation (GUMICS-4) magnetohydrodynamic code. Real solar wind measurements are given t...

Using the Cluster data during the period from January to April between 2001 and 2006, we find an observation of solar wind entry due to magnetic reconnection occurred in the terrestrial high-latitude magnetospheric lobes, tailward of the cusps under northward interplanetary magnetic field (IMF). Occurrence rate of solar wind entry events in this st...

Understanding the capability of a simulation to reproduce observed features is a requirement for its use in operational space weather forecasting. We compare statistically ionospheric seasonal variations in the Grand Unified Magnetosphere-Ionosphere Coupling Simulation (GUMICS-4) global magnetohydrodynamic (MHD) model with measurements. The GUMICS-...

Magnetic reconnection (MR) is a key physical concept explaining the addition of magnetic flux to the magnetotail and closed flux lines back-motion to the dayside magnetosphere. This scenario elaborated by [19], can explain many aspects of solar wind-magnetosphere interaction processes, including substorms. However, neither the Dungey model nor its...

The Hot Ion Analyser (HIA), part of the Cluster Ion Spectrometry experiment, has the objective to measure the three-dimensional velocity distributions of ions. Due to a variety of factors (exposure to radiation, detector fatigue and aging, changes in the operating parameters, etc.), the particles' detection efficiency changes over time, prompting f...

In this paper the turbulent dynamics of a hot flow anomaly (HFA) event is investigated. The HFAs are transient plasma disturbances generated by the interaction of the bow shock (BS) and a tangential discontinuity (TD) embedded in the solar wind. The typical changes of the plasma parameters inside HFAs (increased plasma temperature, low bulk velocit...

The Hot Ion Analyser (HIA), part of the Cluster Ion Spectrometry experiment, has the objective to measure the three-dimensional velocity distributions of ions. Due to a variety of factors (exposure to radiation, detector fatigue and aging, changes in the operating parameters etc.), the particles detection efficiency changes over time, prompting for...

Global magnetohydrodynamic (MHD) modeling is a powerful tool in space physics research. There are several advanced and still developing global MHD codes that are widely used to simulate plasma processes in solar wind magnetosphere-ionosphere system.The verification of global simulation codes is an important but a difficult problem. We present an ap...

The European Commission funded the European Cluster Assimilation Techniques (ECLAT) project as a collaboration of five leading European universities and research institutes. A main contribution of the Finnish Meteorological Institute (FMI) is to provide global MHD runs with the Grand Unified Magnetosphere Ionosphere Coupling simulation (GUMICS) bas...

The European Commission funded the European Cluster Assimilation Techniques (ECLAT) project as a collaboration of five leader European universities and research institutes. A main contribution of the Finnish Meteorological Institute (FMI) is to provide a wide range global MHD runs with the Grand Unified Magnetosphere Ionosphere Coupling simulation...

The Boundary Layer Identification Code (BLIC) project determines automatically four selected boundary layers: the bow shock, the magnetopause, the neutral sheet and the outer rim of the outer radiation belt. The neutral sheet and the radiation belt positions are determined from magnetic field and energized electron measurements, respectively, worki...

Several hot flow anomaly (HFA) like events were observed by STEREO during its Earth orbit phase in November-December 2006 and in the far tail beyond the orbit of the Moon in February-March, 2007. The magnetic signature of the tangential discontinuities was visible, but the resolution of the plasma ion data is not sufficient for our analysis, so a m...

We use Cluster multipoint density measurements, using the spacecraft potential, to identify localized density enhancements (>50%) in the magnetosheath, and estimate their three-dimensional morphology and orientation. Typically one dimension of the density enhancements is shorter than others, is directed perpendicular to the background magnetic fiel...

1] We use Cluster multipoint density measurements, using the spacecraft potential, to identify localized density enhancements (>50%) in the magnetosheath, and estimate their three-dimensional morphology and orientation. Typically one dimension of the density enhancements is shorter than others, is directed perpendicular to the background magnetic f...

It has recently been proposed that ripples inherent to the bow shock during radial interplanetary magnetic field (IMF) may produce local high speed flows in the magnetosheath. These jets can have a dynamic pressure much larger than the dynamic pressure of the solar wind. On 17 March 2007, several jets of this type were observed by the Cluster space...

Modern state-of-the-art web services are from crucial importance for the interoperability of different VO tools existing in the planetary community. SOAP based web services assure the interconnectability between different data sources and tools by providing a common protocol for communication. This paper will point out a best practice approach with...

Bell et al. (2009) proposed that the source region for banded chorus consists of whistler mode ducts of depleted electron density (Ne) for upper band (UB) chorus for all wave normal angles (θ) and ducts of either enhanced or depleted Ne for lower band (LB) chorus for small θ and θ near or greater than the Gendrin angle, respectively. This paper pro...

The Waves of HIgh frequency and Sounder for Probing of Electron density by Relaxation (WHISPER) instrument is part of the Wave Experiment Consortium (WEC) of the CLUSTER mission. With the help of the long double sphere antennae of the Electric Field and Wave (EFW) instrument and the Digital Wave Processor (DWP), it delivers active (sounding) and na...

Hot flow anomalies (HFAs) are studied using observations of the FGM magnetometer and the CIS plasma detector aboard the four Cluster spacecraft. Previously we studied several specific features of tangential discontinuities on the basis of Cluster measurements in February–April 2003 and discovered a new condition for forming HFAs that is the solar w...

In our previous studies it has been shown that the spatial and temporal variation of the tur-bulent dynamics of our space environment can be adequately monitored by the investigation of the change of the intermittent properties of in-situ magnetic time-series. In this paper, the variation of the turbulent parameters of the quasi-parallel foreshock...

The Interplanetary Magnetic Field shows complex spatial and temporal variations. Single spacecraft measurements reveal only a one dimensional section of this rich four dimensional phenomenon. Multi-point measurements of the four Cluster spacecraft provide a unique tool to study the spatiotemporal structure of the field. Using Cluster data we determ...

In this paper we study the turbulent and intermittent nature of the terrestrial foreshock region using the FGM magnetic records of the Cluster mission. The investigation of the turbulent dynamics is based on probability density function (PDF), spectral and structure function (SF) analyses of the magnetic signals. It is shown that the level of inter...

Hot flow anomalies (HFAs) were first discovered in the early 1980s at the bow shock of the Earth. In the 1990s these features were studied, observed and simulated very intensively and many new missions (Cluster, THEMIS, Cassini and Venus Express) focused the attention to this phenomenon again. Many basic features and the HFA formation mechanism wer...

Tangential discontinuties (TDs) are usually considered as thin planar current sheets frozen in the solar wind flow. Previous studies based on the magnetic field measurements onboard of ACE, Wind, and STEREO A, and B proved that this hypotesis is not valid. The curvature of the TDs were determined in several cases. After applying minimum variance an...

Several hot flow anomaly (HFA) like events were observed by STEREO magnetometer (MAG) and solar wind thermal proton (PLASTIC) and electron (SWEA) instruments during the Earth orbit phase of STEREO B in February-March, 2007. The magnetic signature of the tangential discontinuities (TDs) was observed but the resolution of PLASTIC is not sufficient to...

The Cluster Active Archive (CAA) aims at preserving the four Cluster spacecraft data, so that they are usable in the long-term by the scientific community as well as by the instrument team PIs and Co-Is. This implies that the data are filed together with the descriptive and documentary elements making it possible to select and interpret them. The C...

Hot flow anomalies (HFAs) are studied using observations of the magnetometer and the plasma instrument aboard the four Cluster spacecraft. We study several specific features of tangential discontinuities on the basis of Cluster measurements from the time periods of February–April 2003, December 2005–April 2006 and January–April 2007, when the separ...

The paper concerns with the investigation of the nonlinear properties of the plasma dynamics inside hot flow anomalies (HFA). The HFAs are high-energy plasma populations that occur in the solar wind near the planetary bow shocks due to the convergence of upstreaming particles towards a tangentional discontinuity plane in the solar wind. The converg...

Hot flow anomalies (HFAs) are studied using observations of the RAPID suprathermal charged particle detector, the FGM magnetometer, and the CIS plasma detector aboard the four Cluster spacecraft. Previously, we studied several specific features of tangential discontinuities on the basis of Cluster measurements in February–April 2003. In this paper,...

The paper concerns with the study of the nonlinear properties of the plasma fluctuations near and inside hot flow anomalies (HFA). The phenomenon termed HFA evolves due to the interaction between the bow shock and a tangential discontinuity in the upstream plasma. Often, the events are coupled to high-energy particle flux. Furthermore, inside and a...

Hot flow anomalies are temporary disturbances of the Earth's bow-shock or more exactly the upstream region's events. These events have been observed in 1985 by AMPTE and ISEE missions beyond the bow-shock.I have examined Cluster FGM, RAPID and CIS HIA measurements throughout spring of 2003 and have proven that these events are not as infrequent as...

In the present paper, we have studied the effect of plasma mixing on the small-scale field configurations. We have employed theoretical models and numerical simulations to describe magnetic field structures formed by the mixing motion of the interplanetary plasma. The small-scale magnetic fluctuations share properties with waves and with turbulence...

A series of events having signatures of hot flow anomalies (HFA) observed by the magnetic field, plasma, and energetic particle instruments aboard the Cluster spacecraft upstream of the Earth’s bow shock in February–April 2003 are investigated. During this period, the separation of the four satellites (up to about 10,000 km) allowed determining the...

Hot flow anomalies are studied using observations of the FGM magnetometer and the CIS plasma detector aboard the four Cluster spacecraft. The identification of Hot Flow Anomalies (HFAs), discovered nearly 20 years ago near the Earth's bow shock, and their distinction from other events is still not straightforward. We studied general features of HFA...

Known for about 20 years, the explanation of hot flow anomaly events is still far from being complete. Among the few hybrid simulations the results of Lin (2002) are cited frequently. We check some of its predictions using FGM and CIS measurements aboard Cluster. Several known geometrical features are verified and the average size of the affected d...

Hot flow anomalies are studied using observations of the RAPID suprathermal charged particle detector the FGM magnetometer and the CIS plasma detector aboard the four Cluster spacecraft The identification of Hot Flow Anomalies HFAs discovered nearly 20 years ago near the Earth s bow shock and their distinction from other events is still not straigh...

Discovered nearly 20 years ago near the Earth's bow shock, the identification and separation of Hot Flow Anomalies (HFAs) from other events is still under debate. We have used the observations of instruments FGM, CIS, and RAPID aboard the four Cluster spacecraft to detect and study these phenomena. The definition and basic features of HFAs (size, d...

The Cluster mission has been designed to perform simultaneous 3D plasma, magnetic field and energetic particles measurements in the Earth's plasma environment. The advanced energetic charged particle spectrom-eter RAPID on board the four spacecraft provide a complete coverage of energy, mass, and angular distribution of ions and electrons, over the...

The relation of coronal mass ejections (CMEs) and solar energetic particle events (SEPs) is a field where our understanding of the underlying physical processes has been subject to rapid changes recently. Two paradigms are still competing: the earlier one is that solar energetic particle events (SEPs) are triggered by flares. The recently more popu...

The LION experiment on SOHO (which records protons from 44 keV-6 MeV and electrons from 44 keV-300 keV), and the energetically complementary EPHIN experiment (which measures protons + helium ions to >53 MeV/n and electrons to >5 MeV), each detected many energetic particle events (SEPs) in the early rising phase of Solar Cycle 23 (from ~ July 1996)...

It is well known that the Interplanetary Magnetic Field shows rich, highly complicated field configurations. Various processes can contribute to the formation of these rich structures, including Alfvenic waves, discontinuities, or the field line motion due to plasma mixing. Four-point measurements provide a new tool to distinguish the field configu...