Massimo Materassi

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Verified

Massimo verified their affiliation via an institutional email.

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• PhD
• Researcher at Italian National Research Council

In this review paper, the equations of motion describing the fluid dynamics of the ionosphere are constructed step by step, so that any master or post-graduate student may get familiar with the general theory of the “traditional” approach to Ionospheric Physics, in which chemicals forming the Earth’s upper atmosphere are represented as fluids in mu...

In this review paper the equations of motion describing the fluid dynamics of the ionosphere are constructed step by step, so that any master or post-graduate student may get familiar with the general theory of the “traditional” approach to Ionospheric Physics, in which chemicals forming the Earth’s upper atmosphere are represented as fluids in mut...

Theoretical modelling of the local ionospheric medium (LIM) is made difficult by the occurrence of irregular ionospheric behaviours at many space and time scales, making prior hypotheses uncertain. Investigating the LIM from scratch with the tools of dynamical system theory may be an option, using the vertical total electron content (vTEC) as an ap...

Learning from successful applications of methods originating in statistical mechanics, complex systems science, or information theory in one scientific field (e.g., atmospheric physics or climatology) can provide important insights or conceptual ideas for other areas (e.g., space sciences) or even stimulate new research questions and approaches. Fo...

Modelling the Earth’s ionosphere is a big challenge, due to the complexity of the system. Different first principle models have been developed over the last 50 years, based on ionospheric physics and chemistry, mostly controlled by Space Weather conditions. However, it is not understood in depth if the residual or mismodelled component of the ionos...

In 1982 in a series of works Vielliefosse [1, 2] discussed a nonlinear homogeneous evolution equation for the velocity gradient tensor in fluid dynamics. Later Cantwell [3] extended this formalism to the non-homogeneous case including the effects of viscous diffusion and cross derivatives of pressure field. Here, we derive the evolution equations o...

Significant evidence of ionosphere and magnetosphere disturbance in connection to intense seismic events have been detected since two decades. It is generally believed that the energy transfer can be due to Acoustic Gravity Waves (AGW) excited at ground level by the earthquakes. In spite of the statistical evidence of the detected perturbations, th...

Ionospheric medium fluctuations are detected at various spatial and temporal scales. Plasma irregularities encountered crossing high latitude current systems can be extremely thin and therefore, unlikely to identify with standard detectors. This work aims to show plasma layer features obtained by electric field instrument on-board the Chinese Seism...

The short-term prediction of earthquakes is an essential issue connected with human life protection and related social and economics matter. Recent papers have provided some evidence of the link between the lithosphere, lower atmosphere, and ionosphere, even though with marginal statistical evidence. The basic coupling hypothesized being via atmosp...

Significant evidence of ionosphere disturbance in connection to intense seismic events have been detected since two decades. It is generally believed that the energy transfer can be due to Acoustic Gravity Waves (AGW) excited at ground level by the earthquakes. In spite of the statistical evidence of the detected perturbations, the coupling between...

We consider networks of dynamical units that evolve in time according to different laws, and are coupled to each other in highly irregular ways. Studying how to steer the dynamics of such systems towards a desired evolution is of great practical interest in many areas of science, as well as providing insight into the interplay between network struc...

In this brief work we present a novel approach to the logistic dynamics of populations and epidemic spreading that can take into account of the complex nature of such a process in several real situations, where due to different agents the dynamics is no longer characterized by a single characteristic timescale, but conversely by a distribution of t...

The short-term prediction of earthquakes is an essential issue connected with human life protection and related social and economic matters. Recent papers have provided some evidence of the link between the lithosphere, lower atmosphere, and ionosphere, even though with marginal statistical evidence. The basic coupling is hypothesized as being via...

Algorithms based on Empirical Mode Decomposition (EMD) and Iterative Filtering (IF) are largely implemented for representing a signal as superposition of simpler well-behaved components called Intrinsic Mode Functions (IMFs). Although they are more suitable than traditional methods for the analysis of nonlinear and nonstationary signals, they could...

Some ideas are presented about a geometric motivation of the apparent capacity of generalized logistic equations to describe the outbreak of quite many epidemics, possibly including that of the COVID-19 infection. This interpretation pivots on the complex, possibly fractal, structure of the locus describing the “contagion event set”, and on what ca...

The dynamical variables ψ of a classical system, undergoing stochastic stirring forces, satisfy equations of motion with noise terms. Hence, these ψ show a stochastic evolution themselves. The probability of each possible realization of ψ within a given time interval, arises from the interplay between the deterministic parts of dynamics and the sta...

Some ideas are presented about a geometric motivation of the apparent capacity of generalized logistic equations to describe the outbreak of quite many epidemics, possibly including that of the COVID-19 infection. This interpretation pivots on the complex, possibly fractal, structure of the locus describing the “contagion event set”, and on what ca...

Some ideas are presented about the physical motivation of the apparent capacity of generalized logistic equations to describe the outbreak of the COVID-19 infection, and in general of quite many other epidemics. The main focuses here are: the complex, possibly fractal, structure of the locus describing the “contagion event set”; what can be learnt...

We consider networks of dynamical units that evolve in time according to different laws, and are coupled to each other in highly irregular ways. Studying how to steer the dynamics of such systems towards a desired evolution is of great practical interest in many areas of science, as well as providing insight into the interplay between network struc...

We analyze the amplitude scintillation on L-band signals over San Miguel de Tucumán (Argentina), focusing on the multi-scale variability and speculating on the possible relationship between forcing factors from the geospace and the ionospheric response. The site is nominally located below the expected position of the southern crest of the Equatoria...

The concept of stochastic Lagrangian and its use in statistical dynamics is illustrated theoretically, and with some examples. Dynamical variables undergoing stochastic dierential equations are stochastic processes themselves, and their realization probability functional within a given time interval arises from the interplay between the determinist...

In a recent paper, Consolini et al. investigated the statistics of geometrical invariants of the coarse-grained gradient tensor of plasma velocity for a case study of space plasma turbulence. They showed how, at spatial scales near the proton inertial length, there is evidence for the occurrence of dissipation structures along the Vieillefosse’s ta...

The evaluation of the external origin contribution (BEXT and EEXT) in geomagnetic field satellite ob-servations in the near Earth location (1.2 RE<R<1.5 RE; RE being the Earth radius) during active magnetic conditions is one of the key problem in the Space Weather context. We propose an inno-vative algorithm able to discriminate the external from t...

In order to construct an analytical model of evolution for the plasma structures in the ionospheric Equatorial Spread F, an attempt is presented to include the plasma perturbations “seeding” the instabilities that cause the Equatorial Spread F in a theoretically consistent way. This is done assuming that the local discrepancies from quasi neutralit...

This work aims at showing how analysis techniques, designed to highlight the multi-scale structure of a signal, may be of help in describing fluctuations of the ionospheric medium. In particular, the technique used here is the ALIF (Adaptive Local Iterative Filter). We have applied ALIF to the characterisation of plasma irregularities in the equato...

In order to construct an analytical model of evolution for the plasma structures in the ionospheric Equatorial Spread F, an attempt is presented to include the plasma perturbations seeding the instabilities that cause the Equatorial Spread F in a theoretically consistent way. This is done assuming that the local discrepancies from quasi neutrality...

Introduction. Birkeland currents (field-aligned currents-FACs) flow along magnetic field lines to connect magnetospheric current systems to the high latitudes ionospheric currents. Within the polar cap, tail-shape magnetic field lines are tilted antisunward by the flow of the solar wind, whereas in the return flow region field lines are tilted sunw...

The evaluation of the external origin contribution (BEXT and EEXT) in geomagnetic field satellite observations in the near Earth location (1.2 RE<R<1.5 RE; RE being the Earth radius) during active magnetic conditions is one of the key problem in the Space Weather context. We propose an innovative algorithm able to discriminate the external from the...

Metriplectic dynamics couple a Poisson bracket of the Hamiltonian description with a kind of metric bracket, for describing systems with both Hamiltonian and dissipative components. The construction builds in asymptotic convergence to a preselected equilibrium state. Phenomena such as friction, electric resistivity, thermal conductivity and collisi...

Metriplectic dynamics couple a Poisson bracket of the Hamiltonian description with a kind of metric bracket, for describing systems with both Hamiltonian and dissipative components. The construction builds in asymptotic convergence to a preselected equilibrium state. Phenomena such as friction, electric resistivity, thermal conductivity and collisi...

Many real life signals, and in particular in the space physics domain, exhibit variations across different temporal scales. Hence, their statistical momenta may depend on the time scale at which the signal is studied. To identify and quantify such variations, a time-frequency analysis has to be performed on these signals. The dependence of the stat...

A dynamical system defined by a metriplectic structure is a dissipative model characterized by a specific pair of tensors, which defines a Leibniz bracket; and a free energy, formed by a “Hamiltonian” and an entropy, playing the role of dynamics generator. Generally, these tensors are a Poisson bracket tensor, describing the Hamiltonian part of the...

A dynamical system defined by a metriplectic structure is a dissipative model characterized by a specific pair of tensors, which defines the Leibniz brackets. Generally, these tensors are Poisson brackets tensor and a symmetric metric tensor that models purely dissipative dynamics. In this paper, the metriplectic system describing a simplified two-...

The metriplectic formalism couples Poisson brackets of the Hamiltonian description with metric brackets, for describing systems with both Hamiltonian and dissipative components. The construction builds in asymptotic convergence to a preselected equilibrium state. Phenomena such as friction, electric resistivity, thermal conductivity and collisions...

Many real life signals, and in particular in the space physics domain, exhibit variations across different temporal scales. Hence, their statistical momenta may depend on the time scale at which the signal is studied. To identify and quantify such variations, a time-frequency analysis has to be performed on these signals. The dependence of the stat...

Analysis of the radio scintillation and ionospheric fluctuation data at low latitude focusing on the time and space multi-scale variability and on the causal relationship between forcing factors from the SW environment and the ionospheric response.

Scavenging is ubiquitous in nature, but its implications have rarely been investigated. We used camera traps on wolf kills to investigate the role of scavenging on predator and multiprey dynamics in a northern Apennine system in Italy. In contrast to North American systems, the omnivorous wild boar successfully competes with wolves for the meat of...

The metriplectic formalism couples Poisson brackets of the Hamiltonian description with metric brackets for describing systems with both Hamiltonian and dissipative components. The construction builds in asymptotic convergence to a preselected equilibrium state. Phenomena such as friction, electric resistivity, thermal conductivity and collisions i...

WAM is realized making use of the plasma density data collected via the retarding potential analyser on board the Dynamics Explorer 2 spacecraft, capable to model the scintillation climatology over the northern hemisphere high latitude ionosphere. More recently, WAM has been tuned to model the ionospheric scintillations also over the equatorial lat...

Radio power scintillation, namely highly irregular fluctuations of the power of trans-ionospheric GNSS signals, is the effect of ionospheric plasma turbulence. The scintillation patterns on radio signals crossing the medium inherit the ionospheric turbulence characteristics of inter-scale coupling, local randomness and large time variability. On th...

Nonlinear and nonstationary signals are ubiquitous in real life. Their decomposition and analysis is of crucial importance in many research fields. Traditional techniques, like Fourier and wavelet Transform have been proved to be limited in this context. In the last two decades new kind of nonlinear methods have been developed which are able to unr...

In this work the effects of kleptoparitism in a multi-trophic food-web, in which an omnivorous species scavenges the kills of a top predator, are investigated. Scavengers are assumed to be able to steal predators’ kills by direct interference and aggression. The amount of prey shared depends on the relative competitive abilities of omnivores and pr...

This lecture is a short review on the role entropy plays in those classical dissipative systems whose equations of motion may be expressed via a Leibniz Bracket Algebra (LBA). This means that the time derivative of any physical observable f of the system is calculated by putting this f in a “bracket” together with a “special observable” F, referred...

Highly irregular fluctuations of the power of trans-ionospheric GNSS signals, namely radio power scintillation, are, at least to a large extent, the effect of ionospheric plasma turbulence, a by-product of the non-linear and non-stationary evolution of the plasma fields defining the Earth’s upper atmosphere. One could expect the ionospheric turbule...

In this work we discuss an application of the Tetrad Dynamics approach, a stochastic dynamical theory already introduced in hydrodynamic turbulence, to incompressible magneto-hydrodynamics. This theoretical framework is capable of taking into account some crucial aspects of turbulent plasmas, namely, (i) its material nature, which is stressed throu...

This lecture is a short review on the role entropy plays in dissipative dynamics formulated in terms of Leibniz bracket algebræ (LBA). While conservative dynamics is given an LBA formulation in the Hamiltonian framework, with total energy H generating the motion via classical Poisson brackets or quantum commutation brackets, an LBA formulation can...

In the last decade, significant advances have been presented for the theoretical characterization and experimental techniques used to measure and model all of the components of the velocity gradient tensor in the framework of fluid turbulence. Here, we attempt the evaluation of the small-scale velocity gradient tensor for a case study of space plas...

The dynamics of dissipative fluids in Eulerian variables may be derived from an algebra of Leibniz brackets of observables, the metriplectic algebra, that extends the Poisson algebra of the frictionless limit of the system via a symmetric semidefinite component, encoding dissipative forces. The metriplectic algebra includes the conserved total Hami...

The dynamics of dissipative fluids in Eulerian variables may be derived from an algebra of Leibniz brackets of observables, the metriplectic algebra, that extends the Poisson algebra of the frictionless limit of the sytem via a symmetric semidefinite component, that generates dissipative forces. The metriplectic algebra includes the conserved total...

The use of transfer entropy has proven to be helpful in detecting which is the verse of dynamical driving in the interaction of two processes, X and Y. In this paper, we present a different normalization for the transfer entropy, which is capable of better detecting the information transfer direction. This new normalized transfer entropy is applied...

The Earth's plasmasphere variability is a consequence of the Sun's forcing, determining our planet's space weather. Plasmaspheric dynamics could be entirely caught only by studying together global and local proxies of the state of this extended system.

The ISIS project (Inter-Satellite & In Situ plasmaspheric monitoring and modelling) aimed to design a system for the continuous monitoring of the Earth’s plasmasphere based on the future Galileo satellites. The ISIS Team proposed new experimental facilities on board of future generation Galileo satellites, designed to realize inter-satellite and i...

We describe the introduction of the first all-sky imaging system for low-light-level optical observations of the disturbed ionosphere over mid-latitude Europe. Using 6300 Å auroral emissions that come from the 200-400 km altitude range, we demonstrate that sub-visual optical patterns spanning the European continent can be obtained from a single sit...

The formulation of Action Principles in Physics, and the introduction of the Hamiltonian framework, reduced dynamics to bracket algebra of observables. Such a framework has great potentialities, to understand the role of symmetries, or to give rise to the quantization rule of modern microscopic Physics. Conservative systems are easily algebrized vi...

Certain modern radio systems that rely on trans-ionospheric propagation require knowledge of the changes in the ionosphere that can be characterised by changes in total electron content (TEC). An important cause of these TEC fluctuations is travelling ionosphere disturbances (TIDs). Temporal variations of European mid-latitude TEC measurements obta...

The metriplectic framework, which permits to formulate an algebraic structure for dissipative systems, is applied to visco-resistive Magneto-Hydrodynamics (MHD), adapting what had already been done for non-ideal Hydrodynamics (HD). The result is obtained by extending the HD symmetric bracket and free energy to include magnetic field dynamics and re...

The extension and the local plasma properties of the Earth's plasmasphere are governed by the interaction with the magnetosphere above (in turn forced by the solar wind) and by the matter exchange and electromagnetic coupling with the underlying ionosphere. The variability of the plasmasphere, as a consequence of the Sun's forcing, defines our plan...

One of the most interesting aspects of the global magnetospheric response to solar wind changes is the relationship between storms and substorms. Here we present new results on the relationship between these two different classes of magnetospheric phenomena by approaching the problem on the side of information theory. Using the Auroral Electrojet A...

Transionospheric radio signals may experience fluctuations in their amplitude and phase due to irregularity in the spatial electron density distribution, referred to as scintillation. Ionospheric scintillation is responsible for transionospheric signal degradation that can affect the performance of satellite based navigation systems. Usually, the s...

It is rather well recognized that the global dynamics of the Sun–Earth relationship involves complex nonlinear phenomena. Here we present a preliminary attempt to characterize the influence and the timing of the solar magnetic activity on the near-Earth environment, based on quite novel tools based on concepts from information theory.In detail, we...

Magnetohydrodynamics in two dimensions is of particular use in all those contexts where the plasma is strongly magnetized in a given direction, so that its relevant dynamics takes place almost only on the plane perpendicular to the strong 'guiding' field. This approach, referred to as reduced MHD, is of great use for describing the fusion plasma in...

Magneto-hydrodynamics in two dimensions, with finite resistivity and viscosity, is of a certain use in all those contexts where the plasma is strongly magnetized in a given direction, so that its relevant dynamics takes place almost only on the plane perpendicular to the strong 'guiding' field. This approach is sometimes called reduced MHD. In turb...

Radar data collected at an experimental facility arranged on purpose suggest that the footprint of atmospheric turbulence might be encoded in the radar signal statistics. Radar data probability distributions are calculated and nicely fitted by a one-parameter family of generalized Gumbel (GG) distributions, Ga. A relation between the wind strength...

The equatorial anomaly is the dominant structure in free electron concentration in the tropical ionosphere. Due to its edges (crests) which are characterised by steep latitudinal gradients in TEC and are temporally and spatially variable, it is one of the ionospheric regions most difficult to image with inversion methods. In this paper we reconstru...

The study of amplitude scintillation on GPS radio links is usually done after detrending the time series of the transmitted power so to define scintillations as the chaotic fluctuation around a unitary value. In a sense, the choice of how to detrend the time series is part of the definition of scintillation.Here we analyse how far the continuous wa...

This paper presents a review of the ionospheric scintillation monitoring and modelling by the European groups involved in COST 296. Several of these groups have organized scintillation measurement campaigns at low and high latitudes. Some characteristic results obtained from the measured data are presented. The paper also addresses the modeling act...

Within the next October 2008 the Indian satellite OCEANSAT-2 will be launched. This satellite is a follow-on mission to the first one which had a scatterometer and an Ocean Color Monitoring (OCM) instrument onboard both devoted to ocean investigation and applications (prediction of cyclone trajectory, fishery, coastal zone mapping, etc.). For the s...

Transionospheric radio signals may experience fluctuations in their amplitude and phase due to irregularity in the spatial electron density distribution, referred to as scintillation. Ionospheric scintillation is responsible for transionospheric signal degradation that can affect the performance of satellite based navigation systems. Usually, the s...

The studies on space plasma turbulence mainly focused on the spectral and statistical features of magnetic and plasma parameter longitudinal fluctuations. This description is, however, incomplete being the longitudinal velocity and/or magnetic field difference only one of the locally independent components of the gradient tensors governing the glob...

Classical systems stirred by random forces of given statistics may be described via a path integral formulation in which their degrees of freedom are stochastic variables themselves, undergoing a multiple-history probabilistic evolution. This framework seems to be easily applicable to resistive Magneto-Hydro-Dynamics (MHD). Indeed, MHD equations fo...

Magnetic reconnection is generally discussed via a fluid description. Here, we evaluate the reconnection rate assuming a fractal topology of the reconnection region. The central idea is that the fluid hypothesis may be violated at the scales where reconnection takes place. The reconnection rate, expressed as the Alfvén Mach number of the plasma mov...

Within the next October 2008 the Indian satellite OCEANSAT-2 will be launched. This satellite is a follow-on mission to the first one which had a scat-terometer and an Ocean Color Monitoring (OCM) instrument onboard both devoted to ocean investigation and applications (prediction of cyclone trajectory, fishery, coastal zone mapping, etc.). For the...

The inter-scale coupling in the dynamics of the magnetic field in the Earth's magnetospheric cusp is studied with the technique of transfer entropy. This is a non-linear data analysis technique conceived to determine which is the process that plays the role of the "dynamical driver" between two processes interacting. The time series of the magnet...

1] Amplitude scintillations on GPS links due to diffraction by ionospheric irregularities are traditionally described, in their strength, via the standard deviation of the signal power normalized to its average within 1 min, the S 4 index. One should be very careful in using S 4 and always remember that this quantity contains useful information whe...

Satellite in situ measurements of plasma (electron) density fluctuations provide direct information about the structure and morphology of irregularities that are responsible for scintillation of radio waves on transionospheric links. When supplemented with the ionosphere model and irregularity anisotropy model, they can be applied to model morpholo...

One of the most intriguing processes occurring in space plasmas is the magnetic field reconnection/reconfiguration process, the comprehension of which is still under debate. The classical reconnection models do not take account of the inherent stocasticity displayed by many space plasma properties. For example in the recent past it has been widely...

The p-model is a mathematical construction largely applied in physics to construct intermittent distributions on a real interval and in general to study diadic branching processes (cascades). The model produces a hierarchy of 1d distributions u(n) with n = 0, 1, 2, …, referred to as generations, that may be used to mimic natural irregular signals a...

Imaging the equatorial ionosphere in three dimensions is challenging due to the high diurnal variations at low latitudes. Inversions of total electron content (TEC) together with model-derived TEC data as replacement of measurement data along satellite-to-ground paths allow reconstructing electron densities. The technique is tested using a realisti...

WHAT IS UAMPY? UAMPY (Upper Atmosphere Monitoring for Polar Year 2007-2008) was an Expression of Intent submitted on January 14, 2005 to the IPY joint Committee. After a positive and encouraging outcome of the IPY evaluation and the incorporation of idea 95 ("Multi-instrument observation of the high latitude ionosphere", proposed by Pierre J. Cilli...