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Sabbagh, Dario
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Sabbagh, Dario
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dario.sabbagh@ingv.it
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57076580400
38 results
Now showing 1 - 10 of 38
- PublicationOpen AccessAccuracy of hmF2 estimations, including IRI-2020 options and ionograms validated parameters, compared to ISR measurements at Millstone Hill(2023)
; ; ; ; ; Several empirical formulations used over time to estimate the fundamental ionospheric parameter hmF2 have been compared in this study. These are the first formulation proposed by Shimazaki (1955) (SHI-1955) as a function of the propagation parameter M(3000)F2, the more accurate BSE-1979 formula proposed by Bilitza et al. (1979) and firstly adopted by the International Reference Ionosphere (IRI) model, and the newest Altadill-Magdaleno-Torta-Blanch (AMTB-2013) (Altadill et al., 2013) and SHU-2015 (Shubin, 2015) models, obtained with a different approach with no explicit dependence on any ionospheric parameter and added as alternative options in the IRI-2016. The evaluation of the accuracy of the available formulation is performed by comparing the modeled values of hmF2 with those simultaneously obtained with independent measurements from the Incoherent Scatter Radar (ISR) installed at the Millstone Hill ionospheric station. The database considered consists of 3626 measurements, thus allowing the evaluation of the results for different heliogeophysical conditions. SHI-1955 and BSE-1979 formulations are evaluated also using input data manually scaled from ionograms recorded at the same location, with the aim of evaluating their accuracy when updated with validated data rather than modeled ones. The SHU-2015 is confirmed the best option in any condition, while AMTB-2013 turns out to perform poorly during night, when SHI-1955 and BSE-1979 fed by validated data can be used for trend analyses due to the high correlation with ISR data. Despite this, BSE-1979 performs better with modeled parameters as input, in terms of RMSE and mean deviation from ISR data. The use of SHI-1955 with CCIR-modeled M(3000)F2 is discouraged under daytime conditions even for long trend analyses.70 26 - PublicationOpen AccessApplicazione di OIASA a ionogrammi obliqui di scarsa qualità(2018-02-21)
; ; ; ; ; Lo studio riguarda l’applicazione del sistema OIASA (Oblique Ionogram Automatic Scaling Algorithm) per l’interpretazione automatica degli ionogrammi obliqui a un set di 288 ionogrammi test di scarsa qualità registrati a Icheon (37.14°N, 127.55°E), Corea del Sud, dalla ionosonda VIPIR2 (Vertical Incidence Pulsed Ionospheric Radar, Version 2), allo scopo di testare la capacità di OIASA di scartare ionogrammi non interpretabili a mano da un operatore e così ridurre il numero di output erronei. Alla base del funzionamento di OIASA vi è una tecnica di riconoscimento dell’immagine utilizzata per scalare dagli ionogrammi la Maximum Usable Frequency (MUF) tra le ionosonde ricevente e trasmittente. Allo scopo di ridurre il numero di falsi positivi sono state applicate tecniche di scarto basate sul metodo del massimo contrasto e sull’utilizzo combinato di un algoritmo di conversione degli ionogrammi obliqui in ionogrammi verticali equivalenti e del software Autoscala. Quest’ultima procedura permette di associare a ciascuna MUF autoscalata un valore di un fattore di qualità definito come differenza tra il valore di foF2 ottenuto da Autoscala e quello ricavato dalla MUF stessa per mezzo della legge della secante. I valori delle soglie da applicare ai processi di scarto sono stati infine ottenuti applicando il metodo della curva ROC (Receiver Operating Characteristic curve) al data set in esame.91 70 - PublicationOpen AccessImprovements on foF1 estimation at polar regions(2016-04-17)
; ; ; ; ; The analysis of a sample of polar ionograms reveals that the DuCharme and Petrie empirical formula often fails in the foF1 estimation at polar regions. A study of the discrepancies between modeled and observed foF1 values is presented, using a data set of Antarctic ionograms from different stations. Such discrepancies have been quantitatively evaluated. Based on this study a correction to the DuCharme and Petrie formula is proposed. This correction is performed to be implemented in an improved version of Autoscala software for a particular ionospheric station, in the frame of AUSPICIO (Automatic Interpretation of Polar Ionograms and Cooperative Ionospheric Observations) project.78 57 - 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 AccessA Multiparametric Approach to Study the Preparation Phase of the 2019 M7.1 Ridgecrest (California, United States) Earthquake(2020)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; The 2019 M7.1 Ridgecrest earthquake was the strongest one in the last 20 years in California (United States). In a multiparametric fashion, we collected data from the lithosphere (seismicity), atmosphere (temperature, water vapor, aerosol, and methane), and ionosphere (ionospheric parameters from ionosonde, electron density, and magnetic field data from satellites). We analyzed the data in order to identify possible anomalies that cannot be explained by the typical physics of each domain of study and can be likely attributed to the lithosphere-atmosphere-ionosphere coupling (LAIC), due to the preparation phase of the Ridgecrest earthquake. The results are encouraging showing a chain of processes that connect the different geolayers before the earthquake, with the cumulative number of foreshocks and of all other (atmospheric and ionospheric) anomalies both accelerating in the same way as the mainshock is approaching.350 53 - PublicationRestrictedTesting of the Method Retrieving a Consistent Set of Aeronomic Parameters With Millstone Hill ISR Noontime hₘF₂ Observations(2021)
; ; ; ; ; ; ; Millstone Hill incoherent scatter radar (ISR) noontime hₘF₂ observations in the (2000-2016) period have been used to test the thermospheric parameters from ionosonde observations (THERION) method. The input parameters apart from the standard indices of solar F10.7 and geomagnetic Aₚ activity include noontime fₒF₂ and plasma frequency at 180-km height read from the fₚ(h) height profiles scaled from the ionograms with the Autoscala program. The THERION method provides a self-consistent set of the main aeronomic parameters responsible for the mid-latitude daytime ionospheric F-region formation, hₘF₂ in particular. Overall, 60 dates under various solar and geomagnetic activity levels have been used for the analysis. The retrieved hₘF₂ values demonstrate a standard deviation of 10.6 km, and this is close to the expected inaccuracy of hₘF₂ determination with the Millstone Hill ISR. The correlation coefficient between the retrieved and the observed hₘF₂ is 0.937 ± 0.051, which is significant at the confidence level >99.9%. The undertaken analysis has confirmed the earlier obtained conclusion on the possibility to extract the main aeronomic parameters from the routine ionosonde observations with the THERION method.324 6 - PublicationOpen AccessOIASA application to oblique radio-sounding data recorded in Korea(2017-04-23)
; ; ; ; ; ; ; ; ; ; ; The Oblique Ionogram Automatic Scaling Algorithm (OIASA) has been applied to a data set of oblique ionograms recorded by the Vertical Incidence Pulsed Ionospheric Radar, Version 2 (VIPIR2) ionosonde receiver in Korea. These ionograms are the result of the real-time oblique radio-soundings performed every 15 minutes since September 12, 2016 (day 256) between the Japanese National Institute of Communications Technology ionospheric stations of Kokubunji (35.71°N, 139.46°E), Yamagawa (31.18°N, 130.59°E), Ogimi (26.70°N, 128.12°E), and Sarabetsu (45.18°N, 141.76°E), and the Korean Space Weather Center stations of Icheon (37.14°N, 127.55°E) and Jeju (33.43°N, 126.29°E). A set of 288 poor-quality test mode ionograms for each of the 8 different radiolinks has been selected for this study, and the results are presented. In order to scale the Maximum Usable Frequencies (MUF) between the receiving and the transmitting ionosondes, a filtering procedure for the ionograms noise reduction has been applied in combination with an image recognition technique. Vertical equivalent ionograms have been then obtained using Martyn’s equivalent path theorem, and processed by Autoscala.160 24 - PublicationOpen AccessThermospheric Parameters during Ionospheric G-Conditions(2021)
; ; ; ; ; For the first time thermospheric parameters (neutral composition, exospheric temperature and vertical plasma drift related to thermospheric winds) have been inferred for ionospheric G-conditions observed with Millstone Hill ISR on 11–13 September 2005; 13 June 2005, and 15 July 2012. The earlier developed method to extract a consistent set of thermospheric parameters from ionospheric observations has been revised to solve the problem in question. In particular CHAMP/STAR and GOCE neutral gas density observations were included into the retrieval process. It was found that G-condition days were distinguished by enhanced exospheric temperature and decreased by ~2 times of the column atomic oxygen abundance in a comparison to quiet reference days, the molecular nitrogen column abundance being practically unchanged. The inferred upward plasma drift corresponds to strong ~90 m/s equatorward thermospheric wind presumably related to strong auroral heating on G-condition days183 8 - PublicationOpen AccessAnalysis of the Ionospheric Perturbations Prior to the 2009 L’Aquila and 2002 Molise Earthquakes from Ground- and Space-Based Observations(2021)
; ; ; ; ; ; ; ; ; ; ; The ionospheric responses to the 2009 L’Aquila (local magnitude ML 5.8 main shock on April 6, 2009) and 2002 San Giuliano di Puglia (ML 5.4 and 5.3, major shocks on October 31, 2002, and November 1, 2002; also known as 2002 Molise earthquakes) seismic sequences, both in central Italy, were investigated in a combined ground satellite study. A multiparametric method based on ionosonde observations of sporadic E and F2 ionospheric layers and an appropriate algorithm for the analysis of the Earth’s magnetic field and electron density satellite measurements were applied to the Rome ionosonde and Challenging Minisatellite Payload satellite data, respectively, looking for middle-term precursory ionospheric anomalies within the preparation zone of the corresponding earthquakes under quiet geomagnetic conditions. Some interesting anomalies were detected prior to the 2009 L’Aquila main shock, including ionosonde anomalies during the same day of the larger foreshock (7 days before the main shock) and the previous day, in coincidence with a magnetic field anomaly by satellite. Less consistent results were obtained for the 2002 Molise seismic sequence, likely due to the lower magnitude of the corresponding events, generating a weak pre-earthquake ionospheric response. In this case, only one variation in the magnetic field measured by satellite 9 days prior to the first major shock met the conditions to be considered anomalous.268 22 - PublicationOpen AccessThe Preparation Phase of the 2022 ML 5.7 Offshore Fano (Italy) Earthquake: A Multiparametric–Multilayer Approach(2024-07-16)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; This paper presents an analysis of anomalies detected during the preparatory phase of the 9 November 2022 ML = 5.7 earthquake, occurring approximately 30 km off the coast of the Marche region in the Adriatic Sea (Italy). It was the largest earthquake in Italy in the last 5 years. According to lithosphere–atmosphere–ionosphere coupling (LAIC) models, such earthquake could induce anomalies in various observable variables, from the Earth’s surface to the ionosphere. Therefore, a multiparametric and multilayer approach based on ground and satellite data collected in each geolayer was adopted. This included the revised accelerated moment release method, the identification of anomalies in atmospheric parameters, such as Skin Temperature and Outgoing Longwave Radiation, and ionospheric signals, such as Es and F2 layer parameters from ionosonde measurements, magnetic field from Swarm satellites, and energetic electron precipitations from NOAA satellites. Several anomalies were detected in the days preceding the earthquake, revealing that their cumulative occurrence follows an exponential trend from the ground, progressing towards the upper atmosphere and the ionosphere. This progression of anomalies through different geolayers cannot simply be attributed to chance and is likely associated with the preparation phase of this earthquake, supporting the LAIC approach.26 4