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Ippolito, Alessandro
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Ippolito, Alessandro
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alessandro.ippolito@ingv.it
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27 results
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- 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 AccessCurrent state and perspectives of Space Weather science in Italy(2020-02-28)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; Italian teams have been involved many times in Space Weather observational campaigns from space and from the ground, contributing in the advancing of our knowledge on the properties and evolution of the related phenomena. Numerous Space Weather forecasting and now-casting modeling efforts have resulted in a remarkable add-on to the overall progress in the field, at both national and international level. The Italian Space Agency has participated several times in space missions with science objectives related to Space Weather; indeed, an important field for the Italian scientific and industrial communities interested in Heliophysics and Space Weather, is the development of new instrumentation for future space missions. In this paper, we present a brief state-of-the-art in Space Weather science in Italy and we discuss some ideas on a long-term plan for the support of future scientific research in the related disciplines. In the context of the current roadmap, the Italian Space Agency aims to assess the possibility to develop a national scientific Space Weather data centre to encourage synergies between different science teams with interest in the field and to motivate innovation and new mission concept development. Alongside with the proposed recommendations, we also discuss how the Italian expertise could complement international efforts in a wider international Space Weather context.409 37 - 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 AccessScientific review on the ionospheric absorption and research prospects of a Complex Eikonal model for one-layer ionosphere(2014-08-06)
; ; ; ; ;Settimi, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Ippolito, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Cesaroni, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Scotto, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; ; ; Thepresent paper conducts a scientific review on ionospheric absorption, extrapolating the research prospects of a complex eikonal model for one-layer ionosphere. As regards the scientific review, here a quasi-longitudinal (QL) approximation for nondeviative absorption is deduced which is more refined than the corresponding equation reported by Davies (1990). As regards the research prospects, a complex eikonal model for one-layer ionosphere is analyzed in depth here, already discussed by Settimi et al. (2013). A simple formula is deduced for a simplified problem. A flat, layered ionospheric medium is considered, without any horizontal gradient. The authors prove that the QL nondeviative amplitude absorption according to the complex eikonal model is more accurate than Rawer’s theory (1976) in the range of middle critical frequencies.558 239 - PublicationOpen AccessAutoscaled MUF assimilation in RATIM(2018-05-28)
; ; ; ; ; ; ; A combined vertical and oblique radio-soundings data assimilation procedure is proposed for the Regional Assimilative Three-dimensional Ionospheric Model (RATIM). As described in a previous paper [1], RATIM has demonstrated a good degree of adaptability to different ionospheric conditions, when vertical plasma frequency profiles fp(h) over the Italian area are ingested. The fp(h) assimilation procedure consists in minimizing the root-mean-square deviation RMSD between the observed and modeled profiles at the locations where observations are available. This enables the model to adjust the values of some ionospheric parameters previously described on empirical bases, testing a wide set of values for their variations. Hence, such variations are effectively RATIM free parameters, as they are varied until the best fit for the available profiles is obtained. A Maximum Usable Frequencies (MUFs) ingestion technique has been subsequently introduced in RATIM. A simple HF ray-tracing technique has been used to model the ground range D of a particular radio-link, evaluating the skip distance for a signal obliquely transmitted towards a specific ionosphere, when the signal frequency is set equal to the MUF for the radio-link itself. A simplified ionosphere between the transmitter and the receiver is assumed, extending the same parabolic fp(h) to the whole radio-propagation channel. This profile is constrained to some F2 characteristics linked to the RATIM free parameters. A comparison between the real and simulated D values is then performed for each combination of the free parameters tested during the fp(h) ingestion, introducing a further condition to the fp(h) RMSD minimization. Preliminary studies of the application of this method are presented, when the MUF-ingesting version of RATIM has been applied to the Japanese-South Korean region, and the MUF values ingested have been obtained by the Oblique Ionogram Automatic Scaling Algorithm (OIASA) [2, 3]. RATIM adaptability has been tested, comparing the percentages of success of the adjustment procedure when only fp(h) are ingested and applying the MUFs assimilation with different thresholds for the ΔD=|D[real]-D[RATIM]| values to be acceptable. The minimized fp(h) RMSD values have been also compared in such conditions, along with the ΔD values obtained in adapting conditions. The RATIM ability to reject incorrect data has also been tested, when fp(h) and MUF values are validated by an expert operator.107 52 - PublicationOpen AccessA method for automatic detection of equatorial spread-F in ionograms(2019-01-01)
; ; ; ; ; A method is presented for automatic detection of spread-F. The method is based on an image recognition technique and is applied to ionograms recorded at the ionospheric station of Tucumán (26.9°S, 294.6°E). The performance achieved is statistically evaluated and demonstrated with significant examples. The proposed method improves Autoscala's ability to reject ionograms with insufficient information, including those featuring Spread-F. Automatic identification of cases of spread-F is of additional interest in Space Weather applications, when it helps detect degraded radio propagation conditions. The present data analysis is a retrospective study but forms the basis for real-time application as an extension of Autoscala’s capabilities.279 158 - PublicationRestrictedAn automatic quality factor for Autoscala foF2 values(2013)
; ; ; ;Cesaroni, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Scotto, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Ippolito, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; ; We propose a new parameter for quality evaluation of ionogram traces reconstructed by Autoscala. This parameter efficiently assesses the reliability of the automatic interpretation of ionospheric characteristics. Based on an extensive analysis of the data, the parameter values are statistically associated with the accuracy of foF2 data automatically scaled by Autoscala. Therefore, Autoscala will be improved by providing foF2 accuracy as supplementary output information.370 61 - PublicationRestrictedThe 15 January 2022 Event at Hunga Tonga-Hunga Ha'apai, Recorded by Multiparametric Stations in Italy(2022-04)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;The eruption of the volcano Hunga Tonga-Hunga Ha‘apai on Jan 15, 2022, 04:14:54 UTC, was such energetic that instruments observed different physical phenomena all over the globe. In Italy, the Istituto Nazionale di Geofisica e Vulcanologia (INGV), who is continuously operating different kinds of monitoring networks, as e.g., the Italian Seismic Network (ISN), micro-barometric and infrasonic stations for monitoring the active volcanoes, ionospheric monitoring network (GNSS and ionosonde), recorded seismic, acoustic and electromagnetic signals originated by this exceptional event. The blast wave generated by the volcanic explosion of Hunga Tunga was recorded by the micro-barometric and infrasound stations installed at Phlegrean Fields (PF), at Stromboli volcano and on Mt. Etna. The first arrival was recorded at ~20:00 UTC, after travelling along the “short” great circle (17600 km), was succeeded by a second onset, about 3:40 h later, arriving at PF from the opposite direction. The mean propagation velocity in both directions was calculated as 310 m/s. The stations of the Etna Radio Observatory (ERO) are also equipped with micro-barometers, measuring the atmospheric pressure at a sampling rate of 5 min. The first group of atmospheric shock waves was recorded in the evening of Jan 15, 2022, while 36 hours later the ERO-stations observed a second signal after having completed the second orbit. The magnitude of M5.7 of the Hunga Tonga eruption was strong enough to record core phases (PKIKP, PKP), surface reflection of mantle phases (PP, SS), as well as Rayleigh and Love waves, at many stations of the ISN. The atmospheric waves generated by the eruption generated Travelling Ionospheric Disturbances in the ionosphere detected as disturbances in the Total Electron Content calculated by using GNSS data acquired by the GNSS network of INGV and variations of the ionospheric peak layer parameters (foF2, hmF2), recorded by the ionosonde installed on the Italian territory by INGV.91 8 - PublicationOpen AccessOblique Ionograms Automatic Scaling Algorithm OIASA application to the ionograms recorded by Ebro observatory ionosondeThe oblique ionograms automatic scaling algorithm (OIASA), developed at the INGV for the identification of trace of oblique ionograms, allows the determination of the maximum usable frequency (MUF) for communication between the transmitter and receiver, automatically rejecting poor quality ionograms. A test of the algorithm using data from a campaign of oblique soundings between Dourbes (50.1°N, 4.6°E) and Roquetes (40.8°N, 0.5°E) has been performed. Oblique soundings from three different campaigns have been studied, covering different geomagnetic conditions, in order to study the behavior of the autoscaling algorithm under quiet and perturbed geomagnetic periods. The reported results demonstrate that OIASA performance is not influenced by geomagnetic or ionospheric activity conditions. This demonstrates a satisfactory performance of the automatic scaling algorithm, even under different geomagnetic conditions, the potential application of OIASA as a near-real-time tool for ionospheric monitoring purposes, and its performance for tracking ionospheric effects caused by space weather events.
176 140 - PublicationOpen AccessA procedure for the reliability improvement of the oblique ionograms automatic scaling algorithm(2016)
; ; ; ; ; ; ; ; ;A procedure made by the combined use of the Oblique Ionogram Automatic Scaling Algorithm(OIASA) and Autoscala program is presented. Using Martyn’s equivalent path theorem, 384 oblique soundingsfrom a high-quality data set have been converted into vertical ionograms and analyzed by Autoscala program.The ionograms pertain to the radio link between Curtin W.A. (CUR) and Alice Springs N.T. (MTE), Australia,geographical coordinates (17.60°S; 123.82°E) and (23.52°S; 133.68°E), respectively. The critical frequency foF2values extracted from the converted vertical ionograms by Autoscala were then compared with the foF2valuesderived from the maximum usable frequencies (MUFs) provided by OIASA. A quality factor Q for the MUF valuesautoscaled by OIASA has been identified. Q represents the difference between the foF2value scaled byAutoscala from the converted vertical ionogram and the foF2value obtained applying the secant law to theMUF provided by OIASA. Using the receiver operating characteristic curve, an appropriate threshold level Qtwas chosen for Q to improve the performance of OIASA.301 71
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