Options
De Lauretis, Marcello
Loading...
Preferred name
De Lauretis, Marcello
Alternative Name
De Lauretis, M.
Main Affiliation
28 results
Now showing 1 - 10 of 28
- PublicationOpen AccessSpace Weather Effects Observed in the Northern Hemisphere during November 2021 Geomagnetic Storm: The Impacts on Plasmasphere, Ionosphere and Thermosphere Systems(2022-11-15)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;; ; ; ;; ; ; ; ; ;; ; On 3 November 2021, an interplanetary coronal mass ejection impacted the Earth’s magnetosphere leading to a relevant geomagnetic storm (Kp = 8-), the most intense event that occurred so far during the rising phase of solar cycle 25. This work presents the state of the solar wind before and during the geomagnetic storm, as well as the response of the plasmasphere–ionosphere–thermosphere system in the European sector. To investigate the longitudinal differences, the ionosphere–thermosphere response of the American sector was also analyzed. The plasmasphere dynamics was investigated through field line resonances detected at the European quasi-Meridional Magnetometer Array, while the ionosphere was investigated through the combined use of ionospheric parameters (mainly the critical frequency of the F2 layer, foF2) from ionosondes and Total Electron Content (TEC) obtained from Global Navigation Satellite System receivers at four locations in the European sector, and at three locations in the American one. An original method was used to retrieve aeronomic parameters from observed electron concentration in the ionospheric F region. During the analyzed interval, the plasmasphere, originally in a state of saturation, was eroded up to two Earth’s radii, and only partially recovered after the main phase of the storm. The possible formation of a drainage plume is also observed. We observed variations in the ionospheric parameters with negative and positive phase and reported longitudinal and latitudinal dependence of storm features in the European sector. The relative behavior between foF2 and TEC data is also discussed in order to speculate about the possible role of the topside ionosphere and plasmasphere response at the investigated European site. The American sector analysis revealed negative storm signatures in electron concentration at the F2 region. Neutral composition and temperature changes are shown to be the main reason for the observed decrease of electron concentration in the American sector.659 57 - PublicationOpen AccessEffects on SuperDARN HF radar echoes of sudden impulses of solar wind dynamic pressure(2005)
; ; ; ; ; ; ; ; ; ; ; ; ;In this work we perform a statistical analysis of the ionospheric echo response observed by six radars of the SuperDARN network in the Northern Hemisphere, over 236 Sudden Impulses (SI) of solar wind dynamic pressure events (from 1997 through 2000). For that purpose, we make use of MRS, the Mean Rate of Scattering, as a function of time during the SI event. We classify the events in sudden increases (I events, 144 cases) and decreases (D events, 92 cases) of the solar wind dynamic pressure. Moreover, we make use of the AE index to define two distinct conditions of the ionosphere under which each event may take place: Quiet and Disturbed. Regarding Quiet conditions, for both I and D events, we find that MRS displays an increase related to the SI time. On the contrary, for Disturbed conditions, D events display an increase in MRS, while I events show a clear dip. The similarity of response for I and D events under Quiet conditions is briefly discussed, but the smaller number of D events does not allow one to further analyse them. As for the I events, a latitudinal analysis shows that the MRS increase for Quiet conditions is seen both at low latitudes (60 −70 3) and at high latitudes (70 −80 3); for Disturbed Is the MRS decrease is stronger at high latitudes. We suggest that the MRS increase for Quiet Is can be due to two different mechanisms: 1) a soft electron precipitation induced by Field Line Resonances (FLR) or loss cone instability at lower latitudes; 2) an enlargement of the cusp at higher latitudes, which in turn may induce enhanced particle precipitation. For what concerns Disturbed Is, the MRS decrease can be produced by a higher energy electron precipitation (>1 keV), that enhances the electron density in the E and D regions. This provokes a strong absorbtion of the radio waves in the D region and a higher refraction in the E region, leading to a decrease in MRS, especially at higher latitudes.130 27 - PublicationOpen AccessThe use of the empirical mode decomposition for the identification of mean field aligned reference frames(2016)
; ; ; ; ;The magnetic field satellite data are usually referred to geocentric coordinate reference frame. Conversely, the magnetohydrodynamic waves modes in magnetized plasma depend on the ambient magnetic field, and is then useful to rotate the magnetic field measurements into the mean field aligned (MFA) coordinate system. This reference frame is useful to study the ultra low frequency magnetic field variations along the direction of the mean field and perpendicularly to it. In order to identify the mean magnetic field the classical moving average (MAVG) approach is usually adopted but, under particular conditions, this procedure induces undesired features, such as spectral alteration in the rotated components. We discuss these aspects promoting an alternative and more efficient method for mean field aligned projection, based on the empirical mode decomposition (EMD).181 117 - PublicationOpen AccessSolar wind-driven Pc5 waves observed at a polar cap station and in the near cusp ionosphere(2016)
; ; ; ; ; ; ; ; ; ; ;We present the results of a comparative study conducted in Antarctica by using the ULF geomagnetic field measurements at Terra Nova Bay (Altitude Adjusted Corrected Geomagnetic Coordinates latitude 80°S) and simultaneous data from the Super Dual Auroral Radar Network radar at South Pole Station. Pc5 waves observed at Terra Nova Bay around local magnetic noon, when the station is close to the dayside cusp, can be interpreted as spatial integrated signals, produced by ionospheric currents associated to field line resonances at somewhat lower latitudes. The radar, providing the Doppler velocities of ionospheric plasma over a range of geomagnetic latitudes, allows to detect the occurrence of such field line resonances. In the reported case, our analysis shows evidence of resonant signals in the ionosphere at 75°S and 76°S that find correspondence in frequency and time with the geomagnetic signals observed at Terra Nova Bay around local noon. During the period of interest, oscillations of the solar wind dynamic pressure at the same frequency are detected by Geotail, just upstream of the morning flank of the bow shock. All the observations are consistent with the interpretation of the signals at Terra Nova Bay in terms of signatures of field line resonances occurring at lower latitudes, driven by solar wind oscillations transmitted into the magnetosphere. We discuss also the possibility of an additional contribution to the signals at Terra Nova Bay, due to the direct propagation of the solar wind waves along the local open field line.160 24 - PublicationOpen AccessULF geomagnetic activity effects on tropospheric temperature, specific humidity, and cloud cover in Antarctica, during 2003-2010(2017)
; ; ; ; ; ; ;In the present study we investigated the possible relationship between the ULF geomagnetic activity and the variations of several atmospheric parameters. In particular, we compared the ULF activity in the Pc1-2 frequency band (100 mHz–5 Hz), computed from geomagnetic field measurements at Terra Nova Bay in Antarctica, with the tropospheric temperature T, specific humidity Q, and cloud cover (high cloud cover, medium cloud cover, and low cloud cover) obtained from reanalysis data set. The statistical analysis was conducted during the years 2003–2010, using correlation and Superposed Epoch Analysis approaches. The results show that the atmospheric parameters significantly change following the increase of geomagnetic activity within 2 days. These changes are evident in particular when the interplanetary magnetic field Bz component is oriented southward (Bz <0) and the By component duskward (By > 0). We suggest that both the precipitation of electrons induced by Pc1-2 activity and the intensification of the polar cap potential difference, modulating the microphysical processes in the clouds, can affect the atmosphere conditions.144 36 - PublicationOpen AccessThe geomagnetic coast effect at two 80° S stations in Antarctica, observed in the ULF rangeWe examined the coast effect in Antarctica along the 80 S magnetic parallel. We used the geomagnetic field measurements at the two coastal stations of Mario Zucchelli Station and Scott Base, and, as a reference, at the inland temporary station Talos Dome, during 18 January– 14 March 2008. Spectral analysis in the Pc5 frequency range (1–7 mHz) revealed large differences between coastal and inland stations, such as higher spectral power levels in the vertical component and higher coherence between horizontal and vertical components at coastal stations. Using the interstation method on selected active time intervals, with Talos Dome as a remote reference station, we found that remote reference induction arrows are directed almost perpendicularly with respect to their respective coastlines. Moreover, the singlestation analysis shows that at Talos Dome the amplitude of the induction arrows is much smaller than at coastal stations. These results clearly indicate that coast effect at a few hundred kilometers from the coastline is relatively small. The coast effect on polarization parameters was examined, for a Pc5 event that occurred on 11 March 2008. The results evidenced that the azimuthal angle of polarized signals at one of the coastal stations is largely different with respect to the inland station (by 110 ), while the polarization ratio and ellipticity attain comparable values. We proposed a correction method of the polarization parameters, which operates directly in the frequency domain, obtaining comparable azimuthal angles at coastal and inland stations.
338 120 - PublicationRestrictedA case study of upstream wave transmission to the ground at polar and low latitudes(2012)
; ; ; ; ; ; ; ; ;In this study we analyzed a long-duration ULF wave event detected on 18–19 February 2005 by Cluster satellites, upstream of the nose of the bow shock. The availability of simultaneous data from Geotail satellite, located in the foreshock region close to the dawn flank of the bow shock, allowed us to make a comparison between the observations at the two different sites. The results can be explained in terms of local wave generation, depending on the orientation of the interplanetary magnetic field with respect to the local bow shock normal. In addition, simultaneous data from Polar satellite in the inner magnetosphere and from ground stations in the southern polar cap and at low latitude allowed us to investigate the transmission of the external waves through the magnetosphere up to the ground. The observations suggest different paths of transmission. Waves generated upstream of the bow shock nose directly transmit near the subsolar point, progressively propagate into the magnetosphere and, after conversion into field-guided Alfven modes, reach the ground at high and low latitudes; waves generated on the flanks of the bow shock do not affect the subsolar magnetosphere, and consequently, there is no propagation along the closed field lines at both high and low latitudes. On the other hand, near the geomagnetic pole, the occurrence of pulsations can be related to the transmission across the magnetopause flanks of upstream waves, anywhere generated, as they are convected downstream by the solar wind; the compressional waves do not propagate deeply into the tail lobes but can couple to Alfven-guided waves along the outermost field lines.143 5 - PublicationOpen AccessThe propagation of ULF waves from the Earth's foreshock region to ground: The case study of 15 February 2009(2014)
; ; ; ; ; ; ;A long-duration upstream ultralow frequency (ULF) wave event was detected on 15 February 2009 by Cluster satellites, close to the bow shock nose. A clear wave activity was identified when the interplanetary magnetic field orientation was favorable to the local generation. We examined the wave properties in both the solar wind and the spacecraft frame during a selected time interval and found that foreshock waves were ssentially Alfven waves propagating at a small angle with respect to the interplanetary magnetic field. A comparison of Cluster observations with those on the ground, in the polar cap and at low-latitude stations, confirms the results of previous studies, indicating that upstream waves can reach different ground regions along different paths.131 19 - PublicationOpen AccessA case study of correspondence between Pc1 activity and ionospheric irregularities at polar latitudes(2020)
; ; ; ; ; ; ; ; ; ; ; ; ; A possible driver of precipitation of magnetospheric energetic electrons in the high-latitude atmosphere is represented by electromagnetic ion-cyclotron (EMIC) magnetospheric waves. The precipitating particles produce variations, by collision, in the ionized component of the atmosphere, altering its chemistry and electrical conductivity, with a significant impact on the atmospheric processes. In this framework, it would be significant to find experimental evidence of a correspondence between ionospheric electron density irregularities and the occurrence of Ultra-Low-Frequency (ULF) Pc1 geomagnetic pulsations, i.e., the ground signatures of EMIC waves, at high latitudes. In this work, we face this subject by considering a specific case study occurred on 22 February 2007 during quiet magnetospheric conditions. The study is based on the analysis of simultaneous ULF geomagnetic field and Total Electron Content (TEC) measurements recorded at Mario Zucchelli Station in Antarctica. We show that Pc1 pulsations occur in correspondence to solar wind pressure increases and that, at the same time, the ionosphere is characterized by the presence of ionospheric irregularities. We suggest that a possible link between the Pc1 activity and the ionospheric irregularities may be energetic electron precipitations, driven by EMIC waves generated in the compressed magnetosphere, which produce density variations in the ionized component of the atmosphere.513 83 - PublicationOpen AccessULF Geomagnetic Pulsations at High Latitudes: the Italian contribution(2007)
; ; ; ; ; ; ; ; ; ;Cafarella, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;De Lauretis, M.; Univ. Aquila - Dip. Fisica ;Di Mauro, D.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Francia, P.; Univ. Aquila - Dip. Fisica ;Lepidi, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Meloni, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Palangio, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Villante, U.; Univ. Aquila - Dip. Fisica ;Santarelli, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; ; ; ; ; ; ; ; The study of geomagnetic field variations in Antarctica is important in that local field lines are close to extreme magnetospheric regions, such as the polar cusp, where several generation mechanisms for ULF waves are active. Since the eighties, the Italian scientific community developed a research activity in Antarctica at Mario Zucchelli Station (TNB, CGM latitude 80°S), where magnetic facilities are continuously operating. In this review we present the experimental results obtained by a number of investigations conducted in the last years on geomagnetic pulsations in the Pc3-Pc5 frequency range. We also show compared analyses with measurements from other Antarctic and low latitude stations, and, in particular, a statistical analysis of propagation characteristics of low frequency geomagnetic field fluctuations between the two Antarctic stations, TNB and Scott Base.422 356
- «
- 1 (current)
- 2
- 3
- »