The study of the preparation phase of large earthquakes is essential to understand the physical processes involved, and potentially useful also to develop a future reliable short-term warning system. ...Here we analyse electron density and magnetic field data measured by Swarm three-satellite constellation for 4.7 years, to look for possible in-situ ionospheric precursors of large earthquakes to study the interactions between the lithosphere and the above atmosphere and ionosphere, in what is called the Lithosphere-Atmosphere-Ionosphere Coupling (LAIC). We define these anomalies statistically in the whole space-time interval of interest and use a Worldwide Statistical Correlation (WSC) analysis through a superposed epoch approach to study the possible relation with the earthquakes. We find some clear concentrations of electron density and magnetic anomalies from more than two months to some days before the earthquake occurrences. Such anomaly clustering is, in general, statistically significant with respect to homogeneous random simulations, supporting a LAIC during the preparation phase of earthquakes. By investigating different earthquake magnitude ranges, not only do we confirm the well-known Rikitake empirical law between ionospheric anomaly precursor time and earthquake magnitude, but we also give more reliability to the seismic source origin for many of the identified anomalies.
We analyze data recorded from October 2010 to September 2011, during the ascending phase of the 24th solar cycle, from an Advanced Ionospheric Sounder‐Istituto Nazionale di Geofisica e Vulcanologia ...ionosonde and a GPS Ionospheric Scintillation and total electron content (TEC) monitor scintillation receiver, colocated at low latitude in the Southern American longitudinal sector (Tucumán, 26.9°S, 294.6°E, magnetic latitude 15.5°S, Argentina). The site offers the opportunity to perform spread‐F and GPS scintillation statistics of occurrence under the southern crest of the equatorial ionospheric anomaly. Spread‐F signatures, classified into four types (strong range spread‐F (SSF), range spread‐F, frequency spread‐F (FSF), and mixed spread‐F), the phase and amplitude scintillation index (σΦ and S4, respectively), the TEC, and the rate of TEC parameter, marker of the TEC gradients, that can cause scintillations, are considered. The seasonal behavior results as follows: the occurrence of all four types of spread‐F is higher in summer and lower in winter, while the occurrence of scintillations peaks at equinoxes in the postsunset sector and shows a minimum in winter. The correspondence between SSF and scintillations seems to be systematic, and a possible correlation between S4 and FSF peaks is envisaged at the terminator. The investigation focused also on two particular periods, from 12 to 16 March 2011 and from 23 to 29 September 2011, both characterized by the simultaneous presence of SSF signatures and scintillation phenomena, allowing to discuss the role of traveling ionospheric disturbances as a strong candidate causing ionospheric irregularities.
Key Points
Simultaneous statistics of spread‐F and scintillation occurrence over Tucuman
Correspondence and inhibition of ESF and scintillation
Spread‐F and scintillation signatures related to MSTIDs
We analyze data of ionospheric scintillation in the geographic latitudinal range 44°–88° N during the period of October, November and December 2003 as a first step to develop a "scintillation ...climatology" over Northern Europe. The behavior of the scintillation occurrence as a function of the magnetic local time and of the corrected magnetic latitude is investigated to characterize the external conditions leading to scintillation scenarios. The results shown herein, obtained merging observations from four GISTM (GPS Ionospheric Scintillation and TEC Monitor), highlight also the possibility to investigate the dynamics of irregularities causing scintillation by combining the information coming from a wide range of latitudes. Our findings associate the occurrences of the ionospheric irregularities with the expected position of the auroral oval and ionospheric troughs and show similarities with the distribution in magnetic local time of the polar cap patches. The results show also the effect of ionospheric disturbances on the phase and the amplitude of the GPS signals, evidencing the different contributions of the auroral and the cusp/cap ionosphere.
•State of the art of the lithosphere–atmosphere–ionosphere coupling (LAIC) mechanisms.•Earthquake-related case studies are shown together with unrelated cases.•Models of LAIC are proposed with future ...trends of research.
A systematic multi-parameter and multi-platform approach to study the slow process of earthquake preparation is fundamental to gain some insights on this complex phenomenon. In particular, an important contribution is the integrated analysis between ground geophysical data and satellite data. In this paper we review some of the more recent results and suggest the next directions of this kind of research. Our intention is not to detect a particular precursor but to understand the physics underlying the various observations and to establish a reliable physical model of the preparation phase before an impending earthquake. In this way, future investigation will search for suitable fore-patterns, which the physical model of multi-layers coupling predicts and characterizes by quasi-synchronism in time and geo-consistency in space. We also present alternative explanations for some anomalies which are not actually related to earthquakes, rather to other natural or anthropic processes.
This paper approaches the problem of optimizing energy consumption onboard hybrid vehicles in a general way, considering the main issues to be solved in their conceptuality and, therefore, that are ...often abstracted from the actual structure of the particular drive train that the authors considered. The methods that were described are a harmonization of those used by the authors over the last several years; therefore, although being rather general, they are far from describing the state of the art of scientific literature on this topic. Both parallel and series structures are covered; for either structure, the effect of different functions on management strategies (e.g., pure-electric drive and plug-in recharge capabilities) are discussed. Some more details are supplied in the Case Studies section of this paper, where some of the authors' past experiences are reconsidered in terms of the general approach proposed in this paper.
Severe ionospheric storms occurred at the end of October 2003. During the evening of 30 October a narrow stream of high electron concentration plasma crossed the polar cap in the antisunward ...ionospheric convection. A GPS scintillation receiver in the European high arctic, operating at 1.575 GHz, experienced both phase and amplitude scintillation on several satellite‐to‐ground links during this period. Close examination of the GPS signals revealed the scintillation to be co‐located with strong gradients in Total Electron Content (TEC) at the edge of the plasma stream. The gradient‐drift instability is a likely mechanism for the generation of the irregularities causing some of the scintillation at L band frequencies during this storm. The origin of the high TEC is explored and the possible implications of the work for scintillation forecasting are noted. The results indicate that the GPS scintillation over Svalbard can originate from traceable ionospheric plasma structures convecting from the American sector.
The CSES satellite, developed by Chinese (CNSA) and Italian (ASI) space Agencies, will investigate iono-magnetospheric disturbances (induced by seismicity and electromagnetic emissions of ...tropospheric and anthropogenic origin); will monitor the temporal stability of the inner Van Allen radiation belts and will study the solar-terrestrial coupling by measuring fluxes of cosmic rays and solar energetic particles. In particular the mission aims at confirming the existences (claimed from several analyses) of a temporal correlations between the occurrence of earthquakes and the observation in space of electromagnetic disturbances, plasma fluctiations and anomalous fluxes of high-energy particles precipitating from the inner Van Allen belt. CSES will be launched in the summer of 2017 with a multi-instruments payload able to measure: e.m. fields, charged particles, plasma, TEC, etc. The Italian LIMADOU collaboration will provide the High-Energy Particle Detector (HEPD), designed for detecting electrons (3–200MeV) and proton (30–300MeV)), and participates to develop the Electric Field Detector (EFD) conceived for measuring electric field from ∼DC up to 5MHz.
•On Summer 2017, the CSES satellite will be launched to study the near-Earth e.m., plasma & particles environment.•The scientific objectives are: litho-atmo-ionosphere coupling, seismic precursors, solar-terrestrial physics & cosmic rays.•For CSES, we have built a high-energy particle detector (HEPD) and an electric field detector (EFD).•The article introduces the scientific background, the objectives of CSES and the satellite layout.•We discuss the features of HEPD and EFD, the calibration procedures and the laboratory tests.
Ionospheric scintillations are caused by time- varying electron density irregularities in the ionosphere, occurring more often at equatorial and high latitudes. This paper focuses exclusively on ...experiments undertaken in Europe, at geographic latitudes between ~50°
N
and ~80°
N
, where a network of GPS receivers capable of monitoring Total Electron Content and ionospheric scintillation parameters was deployed. The widely used ionospheric scintillation indices S4 and
represent a practical measure of the intensity of amplitude and phase scintillation affecting GNSS receivers. However, they do not provide sufficient information regarding the actual tracking errors that degrade GNSS receiver performance. Suitable receiver tracking models, sensitive to ionospheric scintillation, allow the computation of the variance of the output error of the receiver PLL (Phase Locked Loop) and DLL (Delay Locked Loop), which expresses the quality of the range measurements used by the receiver to calculate user position. The ability of such models of incorporating phase and amplitude scintillation effects into the variance of these tracking errors underpins our proposed method of applying relative weights to measurements from different satellites. That gives the least squares stochastic model used for position computation a more realistic representation, vis-a-vis the otherwise ‘equal weights’ model. For pseudorange processing, relative weights were com- puted, so that a ‘scintillation-mitigated’ solution could be performed and compared to the (non-mitigated) ‘equal weights’ solution. An improvement between 17 and 38% in height accuracy was achieved when an epoch by epoch differential solution was computed over baselines ranging from 1 to 750 km. The method was then compared with alternative approaches that can be used to improve the least squares stochastic model such as weighting according to satellite elevation angle and by the inverse of the square of the standard deviation of the code/carrier divergence (sigma CCDiv). The influence of multipath effects on the proposed mitigation approach is also discussed. With the use of high rate scintillation data in addition to the scintillation indices a carrier phase based mitigated solution was also implemented and compared with the conventional solution. During a period of occurrence of high phase scintillation it was observed that problems related to ambiguity resolution can be reduced by the use of the proposed mitigated solution.
During the ascending phase of solar cycle 24, a series of interplanetary coronal mass ejections (ICMEs) in the period 7-17 March 2012 caused geomagnetic storms that strongly affected high-latitude ...ionosphere in the Northern and Southern Hemisphere. GPS phase scintillation was observed at northern and southern high latitudes by arrays of GPS ionospheric scintillation and TEC monitors (GISTMs) and geodetic-quality GPS receivers sampling at 1 Hz. Mapped as a function of magnetic latitude and magnetic local time (MLT), the scintillation was observed in the ionospheric cusp, the tongue of ionization fragmented into patches, sun-aligned arcs in the polar cap, and nightside auroral oval and subauroral latitudes. Complementing a companion paper (Prikryl et al., 2015a) that focuses on the high-latitude ionospheric response to variable solar wind in the North American sector, interhemispheric comparison reveals commonalities as well as differences and asymmetries between the northern and southern high latitudes, as a consequence of the coupling between the solar wind and magnetosphere. The interhemispheric asymmetries are caused by the dawn-dusk component of the interplanetary magnetic field controlling the MLT of the cusp entry of the storm-enhanced density plasma into the polar cap and the orientation relative to the noon-midnight meridian of the tongue of ionization.
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