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De Lauretis, Marcello
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De Lauretis, Marcello
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De Lauretis, M.
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28 results
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- PublicationOpen AccessThe 6 April 2009 earthquake at L’Aquila: a preliminary analysis of magnetic field measurements(2010-02-09)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ;Villante, U.; Dipartimento di Fisica, Universit`a L’Aquila, L’Aquila, Italy ;De Lauretis, M.; Dipartimento di Fisica, Universit`a L’Aquila, L’Aquila, Italy ;De Paulis, C.; Dipartimento di Fisica, Universit`a L’Aquila, L’Aquila, Italy ;Francia, P.; Dipartimento di Fisica, Universit`a L’Aquila, L’Aquila, Italy ;Piancatelli, A.; Dipartimento di Fisica, Universit`a L’Aquila, L’Aquila, Italy ;Piancatelli, A.; Dipartimento di Fisica, Universit`a L’Aquila, L’Aquila, Italy ;Pietropaolo, E.; Dipartimento di Fisica, Universit`a L’Aquila, L’Aquila, Italy ;Vellante, M.; Dipartimento di Fisica, Universit`a L’Aquila, L’Aquila, Italy ;Meloni, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Palangio, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Schwingenschuh, K.; Institut f¨ur Weltraumforschung, Graz, Austria ;Prattes, G.; Institut f¨ur Weltraumforschung, Graz, Austria ;Magnes, W.; Institut f¨ur Weltraumforschung, Graz, Austria ;Nenovski, P.; Geophysical Institute, Sofia, Bulgaria; ; ; ; ; ; ; ; ; ; ; ; ;Several investigations reported the possible identification of anomalous geomagnetic field signals prior to earthquake occurrence. In the ULF frequency range, candidates for precursory signatures have been proposed in the increase in the noise background and polarization parameter (i.e. the ratio between the amplitude/power of the vertical component and that one of the horizontal component), in the changing characteristics of the slope of the power spectrum and fractal dimension, in the possible occurrence of short duration pulses. We conducted, with conventional techniques of data processing, a preliminary analysis of the magnetic field observations performed at L’Aquila during three months preceding the 6 April 2009 earthquake, focusing attention on the possible occurrence of features similar to those identified in previous events. Within the limits of this analysis, we do not find compelling evidence for any of the features which have been proposed as earthquake precursors: indeed, most of aspects of our observations (which, in some cases, appear consistent with previous findings) might be interpreted in terms of the general magnetospheric conditions and/or of different sources.600 9736 - PublicationOpen AccessULF Geomagnetic Activity Signatures in the Atmospheric Parameters in Antarctica(IntechOpen, 2018-11-05)
; ; ; ; ; ; ;The study of the solar wind-Earth’s magnetosphere and atmosphere interaction is a topic of great interest. The solar wind energy is transferred to the Earth’s environment also through ultralow frequency (ULF, 1 mHz–5 Hz) waves of the geomagnetic field, with higher efficiency at high latitudes where magnetic reconnection processes occur, making the polar cap an important laboratory for these investigations. Several studies suggest that the atmosphere responds to the geomagnetic activity driven by the solar wind, although the interaction processes are not yet completely understood. In this context, the results of recent investigations, showing the coupling on timescales of 1–2 days between geomagnetic ULF activity and the middle-low (h < 50 km) atmosphere in the polar cap, are summarized, based on geomagnetic measurements at Terra Nova Bay, in Antarctica (λ ~ 80°S) and atmospheric parameters from the reanalysis dataset.55 21 - PublicationRestrictedThe occurrence of upstream waves in relation with the solar wind parameters: A statistical approach to estimate the size of the foreshock region(2014)
; ; ; ; ;We studied the occurrence of upstream waves in the foreshock region and their relationship with the solar wind and interplanetary magnetic field parameters. To this purpose, we developed a method for a careful identification of the upstream wave events. The results of the statistical analyses based on Cluster data (2003–2010 years) confirm that the angle between the bow shock normal direction and the interplanetary magnetic field is the key element for the wave generation; they also show the relationship between the wave occurrence and the solar wind speed and density. We focused our attention on the occurrence of wave events as a function of the distance from the bow shock. The results show that the foreshock region, where we can observe upstream waves, is characterized by an effective size that decreases with the increase of both the solar wind speed and the wave frequency. Due to the relationship between the solar wind speed and the wave frequency, we suggest that such distance is simply a function of the solar wind speed, becoming smaller when the solar wind speed increases, and then the occurring higher frequency upstream waves are confined in a more restricted region.133 2 - PublicationOpen AccessPc5 geomagnetic fluctuations in response to solar wind excitation and their relationship with relativistic electron fluxes in the outer radiation belt 3. Space science(2015)
; ; ; ; ;This study is focused to investigate the Pc5 geomagnetic pulsations in response to the solar wind forcing and their relationship with the relativistic electron flux at geostationary orbit. We analyzed the correlation of the Pc5 power in the magnetosphere and on the ground, at low and high latitude, with the solar wind speed and fluctuation power of the interplanetary magnetic field and solar wind dynamic pressure through the years 2006 to 2010, also examining the relative timing between pulsations and solar wind parameters. We found a very significant correlation of the Pc5 power with simultaneous solar wind pressure fluctuations and with the solar wind speed lagged by several hours; the relative amplitude of the two correlation peaks depending on the solar cycle phase and on the latitude. We also found a strong relationship between the Pc5 power and the >600 keV and >2 MeV electron flux at geosynchronous orbit. Clear evidence emerges that the electron flux follows the Pc5 power by about 2 days; the time delay is a bit longer for the higher energy electrons.145 13 - PublicationOpen AccessElectromagnetic background noise at L'Aquila Geomagnetic Observatory(2014-02)
; ; ; ;Santarelli, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Palangio, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;De Lauretis, M.; Università degli Studi dell'Aquila; ; In this paper we analyze the electromagnetic background noise at L'Aquila Geomagnetic Observatory during 2006 and 2007 in the frequency band 1-100 mHz. In this band a pronounced daily variation is observed both in the natural signals as well as in the artificial ones, giving rise to the problem of separating different contributions of very similar morphology. We analyzed periods when the local K index was approximately zero, in correspondence with minimum of the magnetospheric and ionospheric activity. We found that in our area the main source of artificial noise is constituted by the DC electrified railways.416 239 - PublicationOpen AccessLocal time behaviour of low frequency geomagnetic field fluctuation power at low latitude(2001-02)
; ; ; ;Lepidi, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Francia, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;De Lauretis, M.; Dipartimento di Fisica, Università di L’Aquila, Italy; ; In this paper we present a statistical study of the local time behaviour of low frequency (0.7-4.0 mHz) geomagnetic field fluctuation power at a low latitude station (corrected geomagnetic latitude 36.2°N). The analysis was conducted for two contiguous years during the ascending phase of the solar cycle. We found that the power of the horizontal east-west geomagnetic field component shows a diurnal and seasonal variation which can be related to variations of the ionospheric current system (Sq) mainly produced by dynamo-action in the ionospheric E region. The power of the horizontal north-south geomagnetic field component is higher in the local afternoon with respect to the morning; this asymmetry is more evident during time intervals characterized by high solar wind dynamic pressure.162 308 - PublicationRestrictedULF fluctuations observed along the SEGMA array during very low solar wind density conditions(2013)
; ; ; ; ;We examined several events of geomagnetic field fluctuations related to upstream waves, focusing the attention on the role of the solar wind density in the control of the wave activity. Recently, it was suggested that, when the solar wind density is lower than 2 cm−3, ULF wave activity on the ground dramatically drops. Based on geomagnetic field measurements conducted at low latitude along the SEGMA array, our analysis shows that, for extremely low solar wind densities (below 1 cm−3), the wave activity on the ground disappears, regardless of cone angle conditions favourable to the transmission of upstream waves through the subsolar magnetopause and independently on the solar wind speed; conversely, for solar wind densities in the range ∼1–2 cm−3, ULF fluctuations can be still observed, during favourable cone angle conditions, if the solar wind speed is higher than ∼600 km/s. Such results are confirmed by the analysis of simultaneous measurements on the ground and from the Cluster spacecraft, when moving in the upstream region and in the magnetosheath, during one of the examined events. We suggest that, for extremely low SW densities, the wave generation mechanism is not operating efficiently, since very few ions are reflected by a very weak bow shock.129 2 - 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 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 - PublicationOpen AccessGeomagnetic field variations at low and high latitude during the January 10-11, 1997 magnetic cloud(1998-07-15)
; ; ; ; ; ; ; ; ; ; ;Villante, U.; Dipartimento di Fisica, Università dell'Aquila, L'Aquila, Italy ;Francia, P.; Dipartimento di Fisica, Università dell'Aquila, L'Aquila, Italy ;Lepidi, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;De Lauretis, M.; Dipartimento di Fisica, Università dell'Aquila, L'Aquila, Italy ;Pietropaolo, E.; Dipartimento di Fisica, Università dell'Aquila, L'Aquila, Italy ;Cafarella, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Meloni, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Lazarus, A. J.; Center for Space Research, MIT, Cambridge, USA ;Lepping, R. P.; Lab. for Extraterrestrial Physics, NASA/GSFC, Greenbelt, USA ;Mariani, F.; Dipartimento di Fisica, Università di Roma-Tor Vergata, Italy; ; ; ; ; ; ; ; ; On Jan. 10-11, 1997 a wide magnetic cloud reached the Earth triggering intense geomagnetic activity. Observations performed at low and very high latitude show that the same features appear simultaneously in correspondence to different changes in the solar wind conditions. In particular, highly polarized modes are simultaneously observed at the same discrete frequencies after the passage of the high density solar wind region following the cloud. SI's and ULF waves polarization are also examined in a wide latitudinal and longitudinal extent.346 144
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