Paola De Michelis

Istituto Nazionale di Geofisica e Vulcanologia

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Giuseppe Consolini

Institute for Space Astrophysics and Planetology

145

Roberta Tozzi

Istituto Nazionale di Geofisica e Vulcanologia

Fabio Giannattasio

Istituto Nazionale di Geofisica e Vulcanologia

Igino Coco

Istituto Nazionale di Geofisica e Vulcanologia

Michael Pezzopane

Istituto Nazionale di Geofisica e Vulcanologia

Alessio Pignalberi

Istituto Nazionale di Geofisica e Vulcanologia

Tommaso Alberti

Istituto Nazionale di Geofisica e Vulcanologia

M. F. Marcucci

National Institute for Astrophysics

A. Meloni

Istituto Nazionale di Geofisica e Vulcanologia

Mirko Piersanti

University of L'Aquila

Cooperative Institutions

Istituto Nazionale di Geofisica e Vulcanologia

National Institute for Astrophysics

Institute for Space Astrophysics and Planetology

Sapienza University of Rome

Istituto Nazionale di Fisica Nucleare

University of L'Aquila

Radiotelevisione Italiana (Italy)

University of Rome Tor Vergata

National Research Council

Centre National de la Recherche Scientifique

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Ionospheric Turbulence: A Challenge for GPS Loss of Lock Understanding

Space Weather (2022)

Paola De Michelis Giuseppe Consolini Alessio Pignalberi Giulia Lovati Michael Pezzopane

Abstract Ionospheric irregularities may affect electromagnetic signals propagating through the ionosphere and consequently contribute to the malfunctioning of the Global Navigation Satellite Systems hindering their accuracy and reliability. In this study, we use data recorded on board two of the three satellites of the Swarm constellation (namely, Swarm A and Swarm B) from 15 July 2014 to 31 December 2021 to assess the possible dependence of the Global Positioning System (GPS) signals loss of lock on the presence of a specific kind of ionospheric irregularities. To accomplish this task we study the scaling features of the electron density fluctuations through the structure function analysis simultaneously to the occurrence of loss of lock events through measurements recorded by the Langmuir probes and the precise orbit determination antennas on board Swarm A and Swarm B satellites. We find that the plasma density irregularities in a turbulent state characterized by intermittent structures and extremely high values of the Rate Of change of electron Density Index can lead to GPS loss of lock events. This is always true at mid and high latitudes, especially inside the auroral oval. In the equatorial belt, this happens in at least 75% of identified GPS loss of lock events that basically coincide with the occurrence of plasma bubbles.

Lock (firearm)

Langmuir Probe

10.1029/2022sw003129

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Citations (9)

Scaling properties of magnetic field fluctuations in the quiet Sun

Astronomy and Astrophysics (2022)

Fabio Giannattasio Giuseppe Consolini F. Berrilli Paola De Michelis

Context. The study of the dynamic properties of small-scale magnetic fields in the quiet photosphere is important for several reasons: (i) it allows us to characterise the dynamic regime of the magnetic field and points out some aspects that play a key role in turbulent convection processes; (ii) it provides details of the processes and the spatial and temporal scales in the solar photosphere at which the magnetic fields emerge, vary, and eventually decay; and (iii) it provides physical constraints on models, improving their ability to reliably represent the physical processes occurring in the quiet Sun. Aims. We aim to characterise the dynamic properties of small-scale magnetic fields in the quiet Sun through the investigation of the scaling properties of magnetic field fluctuations. Methods. To this end, we applied the structure functions analysis, which is typically used in the study of complex systems (e.g. in approaching turbulence). In particular, we evaluated the so-called Hölder-Hurst exponent, which points out the persistent nature of magnetic field fluctuations in the field of view targeted at a whole supergranule in the disc centre. Results. We present the first map of a solar network quiet region as represented by the Hölder-Hurst exponent. The supergranular boundary is characterised by persistent magnetic field fluctuations, which indicate the occurrence of longer-memory processes. On the contrary, the regions inside the supergranule are characterised by antipersistent magnetic field fluctuations, which suggest the occurrence of physical processes with a short memory. Classical Kolmogorov homogeneous and isotropic turbulence, for instance, belongs to this class of processes. The obtained results are discussed in the context of the current literature.

Photosphere

QUIET

Hurst exponent

10.1051/0004-6361/202142940

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GPS Loss of Lock Events and Their Dependence on the Interplanetary Magnetic Field Orientation

Journal of Geophysical Research Space Physics (2023)

Giulia Lovati Paola De Michelis Giuseppe Consolini Michael Pezzopane Alessio Pignalberi

Abstract The study investigates the influence of interplanetary magnetic field (IMF) orientation on loss of lock (LoL) events in Global Positioning System signals. We analyzed LoLs recorded on two Swarm satellites between July 2014 and December 2021, examining how the signs of the IMF B x , B y , and B z components affect the distribution of events at high latitudes. Our results reveal an asymmetric distribution of LoL events over 75° magnetic latitude. In the Northern hemisphere, more events occur in the post‐noon sector with negative IMF B y , and in the pre‐noon sector with positive IMF B y . Conversely, in the Southern hemisphere, pre‐noon events increase with negative IMF B y , while post‐noon events increase with positive IMF B y . At lower latitudes (50°–75°), IMF B y does not significantly affect the event distribution, which mainly concentrates in the night sector for both hemispheres. Additionally, we found a connection between IMF B y and B x , primarily due to the IMF spiral structure. Finally, we discuss our findings in the context of the SuperDARN data‐driven model of ionospheric convection patterns, which shows that LoL events frequently cluster in the cusp region, as well as the area where the two convection cells separate.

Noon

10.1029/2023ja031411

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Citations (1)

On the Forecast Horizon of Magnetospheric Dynamics: A Scale‐to‐Scale Approach

Journal of Geophysical Research Space Physics (2018)

Giuseppe Consolini Tommaso Alberti Paola De Michelis

Abstract The Earth's magnetosphere is characterized by a complex dynamics resulting from the interaction of different multiscale processes which can be both directly driven/triggered by the interplanetary magnetic field and the solar wind, and due to internal processes of the magnetosphere. Recently, Alberti et al. (2017, https://doi.org/10.1002/2016JA023175 ) have shown that the fluctuations at distinct timescales of some geomagnetic indices differently respond to interplanetary changes during geomagnetic storms. In detail, using an information theory based approach it has been shown that geomagnetic indices fluctuations occurring at long timescales (typically longer than 200 min) are correlated with physical quantities characterizing the changes of the interplanetary conditions, while the short timescale ones (typically shorter than 200 min) do not seem to be directly related to the same physical quantities. The aim of this work is to identify the nature and character of the scale‐to‐scale fluctuations of two geomagnetic indices, AE and SYM‐H, capable of monitoring different geomagnetic current systems related to the occurrence of geomagnetic storms and substorms. By applying the theory of dynamical systems, we investigate the scale‐to‐scale correlation dimension D 2 and the Kolmogorov entropy K 2 showing the occurrence of a topological phase transition phenomenon between long and short‐timescale fluctuations. Furthermore, our results clearly show that the forecast horizon of fluctuations occurring at timescales shorter than 200 min dramatically decreases down to ∼2 min. The consequences of this result in the framework of Space Weather forecasting is briefly outlined and discussed.

Space Weather

Geomagnetic secular variation

Interplanetary medium

10.1029/2018ja025952

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Citations (22)

Topside ionosphere effective plasma scale height characterization through CSES-01 satellite Langmuir Probes observations

Michael Pezzopane Alessio Pignalberi Igino Coco Giuseppe Consolini Giulia D’Angelo

The topside ionosphere embraces the region extending from the F2-layer electron density peak to the overlying plasmasphere. In this region the electron density monotonically decreases at a vertical rate driven by the plasma scale height, which in turn depends on both the plasma chemical composition and the physical state. Since an accurate and thorough knowledge of the plasma chemical and physical properties at these altitudes is not available with the required spatial and temporal coverage, an effective plasma scale height is usually inferred from topside electron density measurements and used for empirical modelling purposes.In this work, we aim at characterizing the effective plasma scale height (H0) above the F2-layer peak  through in-situ electron density (Ne) observations by Langmuir Probes (LPs) on-board the China Seismo-Electromagnetic Satellite (CSES-01). Additional information is given by the International Reference Ionosphere (IRI) model. CSES-01 is a sun-synchronous satellite flying with an orbital inclination of 97.4°, an altitude of ~500 km, and descending and ascending nodes are at ~14 local time (LT) and ~02 LT, respectively. Calibrated CSES-01 LPs Ne data recorded in the years 2019-2021 provides the information in the topside ionosphere, while IRI provides the Ne values at the F2-layer peak (NmF2) for the same time, latitude, and longitude sounded by CSES-01. These two Ne set of values are used as anchor points to infer H0 through the topside representation given by the NeQuick model. By exploiting the CSES-01 dataset for the years 2019-2021 we deduced the global H0 behavior for daytime (~14 LT) and nighttime (~02 LT) conditions, for low solar activity conditions. Results obtained with CSES-01 observations are compared and validated with corresponding ones provided by COSMIC-1 radio occultation measurements for similar diurnal and solar activity conditions.

International Reference Ionosphere

Plasmasphere

Longitude

Scale height

Langmuir Probe

10.5194/egusphere-egu23-6633

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Auroral observations at the Mario Zucchelli Base (Antarctica). Morphological features.

MmSAI (2009)

Giuseppe Consolini E. P. Balsamo M. Candidi Paola De Michelis M. F. Marcucci

Auroral displays are the visible manifestation of the solar wind-magnetosphereionosphere interaction at the high latitude polar regions. The study of this phenomenon is very relevant for both the investigation of the magnetosphere-ionosphere coupling and the comprehension of the overall magnetospheric dynamics during the so-called magnetic substorms. Here, we present some preliminary results on the morphological features of the auroral emission as observed at the Mario Zucchelli station in Antarctica during a recent winter campaign. In particular, we are going to show how the morphology of the auroral emission changes with the wavelength (630.0 nm, 557.7 nm and 427.8 nm).

High latitude

Source

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Reply to Comment by M. Dumberry [on “Could the Mw> = 9.3 Sumatra Earthquake trigger a geomagnetic jerk?”]

Eos (2005)

Fabio Florindo Paola De Michelis Antonio Piersanti E. Boschi

We thank M. Dumberry for providing the opportunity to discuss further the article [ Florindo et al. , 2005] in which we suggested that the Sumatra earthquake could have triggered a geomagnetic jerk. Dumberry is against our hypothesis for different reasons: (1) The displacement pattern produced by this earthquake is incompatible with the core‐mantle boundary (CMB) deformations required for a torsional oscillation; (2) most of the deformations occurred locally, producing an actual mass displacement that has not involved the entire Earth; and (3) no abrupt change in the length of day (LOD) has been observed after this event.

Jerk

10.1029/2005eo380006

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Citations (1)

Geophysical survey at Talos Dome, East Antarctica: the search for a new deep-drilling site

Annals of Glaciology (2004)

Massimo Frezzotti Gabriele Bitelli Paola De Michelis A. Deponti A. Forieri

Abstract Talos Dome is an ice dome on the edge of the East Antarctic plateau; because accumulation is higher here than in other domes of East Antarctica, the ice preserves a good geochemical and palaeoclimatic record. A new map of the Talos Dome area locates the dome summit using the global positioning system (GPS) (72˚47’ 14’’S, 159˚04’ 2’’ E; 2318.5m elevation (WGS84)). A surface strain network of nine stakes was measured using GPS. Data indicate that the stake closest to the summit moves south-southeast at a few cm a –1 . The other stakes, located 8 km away, move up to 0.33ma –1 . Airborne radar measurements indicate that the bedrock at the Talos Dome summit is about 400m in elevation, and that it is covered by about 1900 m of ice. Snow radar and GPS surveys show that internal layering is continuous and horizontal in the summit area (15 km radius). The depth distribution analysis of snow radar layers reveals that accumulation decreases downwind of the dome (north-northeast) and increases upwind (south-southwest). The palaeomorphology of the dome has changed during the past 500 years, probably due to variation in spatial distribution of snow accumulation, driven by wind sublimation. In order to calculate a preliminary age vs depth profile for Talos Dome, a simple one-dimensional steady-state model was formulated. This model predicts that the ice 100m above the bedrock may cover one glacial–interglacial period.

Dome (geology)

Bedrock

Ice core

10.3189/172756404781814591

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Citations (66)

Unveiling the Core Patterns of High-Latitude Electron Density Distribution at Swarm Altitude

Remote Sensing (2023)

Giulia Lovati Paola De Michelis Tommaso Alberti Giuseppe Consolini

The ionosphere has distinctive characteristics under different solar and geomagnetic conditions, as well as throughout the seasons, and has a direct impact on our technological life in terms of radio communication and satellite navigation systems. In the pursuit of developing highly accurate ionospheric models and/or improving existing ones, understanding the various physical mechanisms that influence electron density dynamics is critical. In this study, we apply the Multivariate Empirical Mode Decomposition (MEMD) method to the electron density distribution in the mid-to-high latitude (above 50° magnetic latitude) regions in order to identify the dominant scales at which these mechanisms operate. The data were collected by the Swarm mission in the Northern Hemisphere. MEMD allows us to separate the main intrinsic modes and assess their relative contributions to the original one, thereby identifying the most important modes and the spatial scales at which they exert influence. Our study spanned the period from 1 January 2016 to 31 December 2021, which was characterized by low solar activity levels. This choice allowed for a more focused investigation of other variables influencing electron density distribution under similar solar activity conditions. We specifically examined the variations of the resulting modes in relation to different seasons and geomagnetic activity conditions, providing valuable insights into the complex behavior of the ionosphere in response to various external factors.

Mode (computer interface)

10.3390/rs15184550

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Citations (1)

On the Complex Nature of Magnetic Field Fluctuations During Geomagnetic Tail Current Disruption

AGUFM (2011)

Giuseppe Consolini Paola De Michelis Roberta Tozzi

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