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  • 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques  (48)
  • 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy
  • INGV  (52)
  • Wiley  (3)
  • Periodicals Archive Online (PAO)
  • Public Library of Science (PLoS)
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  • 1
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    An interhemispheric comparison of GPS phase scintillation with auroral emission observed at the South Pole and from the DMSP satellite (2013)
    INGV
    Details
    Publication Date: 2020-12-03
    Description: The global positioning system (GPS) phase scintillation caused by highlatitude ionospheric irregularities during an intense high-speed stream (HSS) of the solar wind from April 29 to May 5, 2011, was observed using arrays of GPS ionospheric scintillation and total electron content monitors in the Arctic and Antarctica. The one-minute phase-scintillation index derived from the data sampled at 50 Hz was complemented by a proxy index (delta phase rate) obtained from 1-Hz GPS data. The scintillation occurrence coincided with the aurora borealis and aurora australis observed by an all-sky imager at the South Pole, and by special sensor ultraviolet scanning imagers on board satellites of the Defense Meteorological Satellites Program. The South Pole (SP) station is approximately conjugate with two Canadian High Arctic Ionospheric Network stations on Baffin Island, Canada, which provided the opportunity to study magnetic conjugacy of scintillation with support of riometers and magnetometers. The GPS ionospheric pierce points were mapped at their actual or conjugate locations, along with the auroral emission over the South Pole, assuming an altitude of 120 km. As the aurora brightened and/or drifted across the field of view of the all-sky imager, sequences of scintillation events were observed that indicated conjugate auroras as a locator of simultaneous or delayed bipolar scintillation events. In spite of the greater scintillation intensity in the auroral oval, where phase scintillation sometimes exceeded 1 radian during the auroral break-up and substorms, the percentage occurrence of moderate scintillation was highest in the cusp. Interhemispheric comparisons of bipolar scintillation maps show that the scintillation occurrence is significantly higher in the southern cusp and polar cap.
    Description: Published
    Description: R0216
    Description: 1.7. Osservazioni di alta e media atmosfera
    Description: 3.9. Fisica della magnetosfera, ionosfera e meteorologia spaziale
    Description: JCR Journal
    Description: open
    Keywords: Scintillations ; Solar-terrestrial interaction ; Space weather ; Solar variability and solar wind ; Magnetic storms ; 01. Atmosphere::01.02. Ionosphere::01.02.99. General or miscellaneous ; 01. Atmosphere::01.02. Ionosphere::01.02.05. Wave propagation ; 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques ; 01. Atmosphere::01.02. Ionosphere::01.02.07. Scintillations ; 05. General::05.07. Space and Planetary sciences::05.07.02. Space weather
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 2
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    Scintillations effects on satellite to Earth links for telecommunication and navigation purposes (2006)
    INGV
    Details
    Publication Date: 2021-05-17
    Description: Radio wave scintillations are rapid fluctuations in both amplitude and phase of signals propagating through the atmosphere. GPS signals can be affected by these disturbances which can lead to a complete loss of lock when the electron density strongly fluctuates around the background ionization level at small spatial scales. This paper will present recent improvements to the theoretical Global Ionospheric Scintillation Model (GISM), particularly tailored for satellite based navigation systems such GPS coupled with Satellite Based Augmentation System (SBAS). This model has been improved in order to take into account GPS constellation, signals, and receiver response to ionospheric scintillation environments. A new modelling technique, able to describe the scintillation derived modifications of transionospheric propagating fields is shown. Results from GPS derived experimental measurements performed at high and low magnetic latitudes will show preliminary assessments of the scintillation impact on real receivers and system operations. Nevertheless, comparisons between theoretical scintillation models, such as WBMOD and GISM, with GPS derived experimental data will be shown.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
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    A different approach to the analysis of GPS scintillation data (2006)
    INGV
    Details
    Publication Date: 2021-05-17
    Description: Amplitude scintillation data from GPS were analyzed. The objective is to estimate the impact of ionospheric scintillations at Satellite Based Augmentation Systems Ranging and Integrity Monitoring Station (SBAS RIMS) level and at GPS user level. For this purpose, a new approach to the problem was considered. Data were studied from the point of view of the impact of scintillations on the calculation of VTEC at pierce points and ionospheric grid points. An ionospheric grid of 5° 5° surface squares was assumed. From geometrical considerations and taking into account the basic principle to compute VTEC at grid points, with the data analyzed it is shown that scintillations very seldom affect the calculation of a grid point VTEC. Data from all the RIMS and for the entire GPS satellites network must be analyzed simultaneously to describe a realistic scenario for the impact of scintillations on SBAS. Finally, GPS scintillation data were analyzed at user level: service availability problems were encountered.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: ionospheric scintillations ; GPS scintillation monitor ; SBAS ; 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 4
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    GPS scintillations and total electron content climatology in the southern low, middle and high latitude regions (2013)
    INGV
    Details
    Publication Date: 2020-12-14
    Description: In recent years, several groups have installed high-frequency sampling receivers in the southern middle and high latitude regions, to monitor ionospheric scintillations and the total electron content (TEC) changes. Taking advantage of the archive of continuous and systematic observations of the ionosphere on L-band by means of signals from the Global Positioning System (GPS), we present the first attempt at ionospheric scintillation and TEC mapping from Latin America to Antarctica. The climatology of the area considered is derived through Ground-Based Scintillation Climatology, a method that can identify ionospheric sectors in which scintillations are more likely to occur. This study also introduces the novel ionospheric scintillation 'hot-spot' analysis. This analysis first identifies the crucial areas of the ionosphere in terms of enhanced probability of scintillation occurrence, and then it studies the seasonal variation of the main scintillation and TEC-related parameters. The results produced by this sophisticated analysis give significant indications of the spatial/ temporal recurrences of plasma irregularities, which contributes to the extending of current knowledge of the mechanisms that cause scintillations, and consequently to the development of efficient tools to forecast space-weather-related ionospheric events.
    Description: Published
    Description: R0220
    Description: 1.7. Osservazioni di alta e media atmosfera
    Description: 3.9. Fisica della magnetosfera, ionosfera e meteorologia spaziale
    Description: JCR Journal
    Description: open
    Keywords: Scintillations ; Dynamics ; Solar-terrestrial interaction ; Space weather ; Statistical analysis ; 01. Atmosphere::01.02. Ionosphere::01.02.05. Wave propagation ; 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques ; 01. Atmosphere::01.02. Ionosphere::01.02.07. Scintillations ; 05. General::05.07. Space and Planetary sciences::05.07.02. Space weather
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  • 5
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    eSWua: a tool to manage and access GNSS ionospheric data from mid-to-high latitudes (2013)
    INGV
    Details
    Publication Date: 2021-06-16
    Description: The electronic space weather upper atmosphere (eSWua) is a hardware– software system that is based on measurements collected by instruments installed by the Upper Atmosphere Physics Group of the Istituto Nazionale di Geofisica e Vulcanologia (INGV, Italy). More recently, it has also included the Global Navigation Satellite System (GNSS) ionospheric scintillation and total electron content (TEC) monitor (GISTM) stations that are managed and operated by the University of Nottingham (UK). By visiting the eSWua website, it is possible to access the database that has been implemented to organize and manage the large amount of information acquired. The section of the database designed for the TEC and scintillation data has been designed to address the needs of the space weather community as well as of scientific users. Through the web tools, it is possible to visualize, plot, extract and download the data from each station. This interactive website is supported by a structured database, and it provides a powerful tool for the scientific and technological community in the field of telecommunications and space weather. At present, the data transmission procedure, the database population algorithm, the linear plot and polar plot visualization tools, the statistics page, and the user management system are fully operational. Web access to the data and tools has been realized to handle the data from the sites at low, mid and high latitudes. In this report, we present the results of the system for the GNSS data in the Arctic, the Antarctica, and the three GISTM stations operated by the University of Nottingham: Nottingham, Trondheim and Dourbes. Case studies of the efficacy of this system for scientific and application purposes are also presented and discussed.
    Description: Published
    Description: R0223
    Description: 1.7. Osservazioni di alta e media atmosfera
    Description: 5.4. Banche dati di geomagnetismo, aeronomia, clima e ambiente
    Description: JCR Journal
    Description: open
    Keywords: Database ; GNSS ; Global positioning system ; Ionosphere ; Total electron content ; Ionospheric scintillation ; 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques ; 01. Atmosphere::01.02. Ionosphere::01.02.07. Scintillations ; 05. General::05.01. Computational geophysics::05.01.01. Data processing ; 05. General::05.02. Data dissemination::05.02.05. Collections
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 6
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    An example of operation for a partly manned Antarctic geomagnetic observatory and the development of a radio link for data transmission (2009)
    INGV
    Details
    Publication Date: 2017-04-04
    Description: The experience acquired from more than ten years of operation of an Antarctic geomagnetic observatory is described along with the development of data transmission facilities. The observatory was deployed at the Spanish Antarctic Station in 1996. The main instrument was an Overhauser magnetometer deployed in dual axis Helmholtz coils, a δD/δI configuration. The site is only manned during the summer, with the magnetometer left recording throughout the rest of the year. During the 2007-2008 survey the observatory instrumentation has been upgraded with a DMI suspended triaxial fluxgate magnetometer, new sampling hardware and data logging software. Both sampling and timing are carried out under the control of a PIC based microcontroller and GPS receiver. Data presentation, transmission and archiving are performed under the control of a low power embedded PC. For real time access to the data two options have been provided and rigorously tested during the last 10 years: METEOSAT and GOES Data Collection Systems, and recently, a high frequency (HF) digital radio-link, using ionospheric propagation between Antarctica and Spain, has been developed. This latest transmission system is being continuously upgraded, and it would be possible to extend its application to other remote stations. Measurements have been made during the last four years in order to determine the channel characteristics and its variability, mainly the multipath and Doppler spread and the link availability for a given SNR in the receiver. These measurements are being used to design the physical layer of a radiomodem intended to maximize the link capacity keeping the emitted power low.
    Description: Published
    Description: 45-56
    Description: 1.6. Osservazioni di geomagnetismo
    Description: 2.6. TTC - Laboratorio di gravimetria, magnetismo ed elettromagnetismo in aree attive
    Description: JCR Journal
    Description: open
    Keywords: geomagnetic observatories ; geophysical instrumentation ; data transmission ; HF radio ; 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques ; 04. Solid Earth::04.05. Geomagnetism::04.05.08. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 7
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    Near Earth space plasma monitoring under COST 296 (2009)
    INGV
    Details
    Publication Date: 2017-04-04
    Description: This review paper presents the main achievements of the near Earth space plasma monitoring under COST 296 Action. The outputs of the COST 296 community making data, historical and real-time, standardized and available to the ionospheric community for their research, applications and modeling purposes are presented. The contribution of COST 296 with the added value of the validated data made possible a trusted ionospheric monitoring for research and modeling purposes, and it served for testing and improving the algorithms producing real-time data and providing data users measurement uncertainties. These value added data also served for calibration and validation of space-borne sensors. New techniques and parameters have been developed for monitoring the near Earth space plasma, as time dependent 2D maps of vertical total electron content (vTEC), other key ionospheric parameters and activity indices for distinguishing disturbed ionospheric conditions, as well as a technique for improving the discrepancies of different mapping services. The dissemination of the above products has been developed by COST 296 participants throughout the websites making them available on-line for real-time applications.
    Description: Published
    Description: 221-234
    Description: 1.7. Osservazioni di alta e media atmosfera
    Description: 3.9. Fisica della magnetosfera, ionosfera e meteorologia spaziale
    Description: 5.4. Banche dati di geomagnetismo, aeronomia, clima e ambiente
    Description: JCR Journal
    Description: open
    Keywords: Ionosphere ; monitoring ; data validation ; monitoring techniques ; campaigns ; dissemination ; 01. Atmosphere::01.02. Ionosphere::01.02.04. Plasma Physics ; 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques ; 05. General::05.02. Data dissemination::05.02.05. Collections
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 8
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    Measuring GNSS ionospheric total electron content at Concordia, and application to L-band radiometers (2013)
    INGV
    Details
    Publication Date: 2017-04-04
    Description: In the framework of the project BIS - Bipolar Ionospheric Scintillation and Total Electron Content Monitoring, the ISACCO-DMC0 and ISACCO-DMC1 permanent monitoring stations were installed in 2008. The principal scope of the stations is to measure the ionospheric total electron content (TEC) and to monitor the ionospheric scintillations, using high-sampling-frequency global positioning system (GPS) ionospheric scintillation and TEC monitor (GISTM) receivers. The disturbances that the ionosphere can induce on the electromagnetic signals emitted by the Global Navigation Satellite System constellations are due to the presence of electron density anomalies in the ionosphere, which are particularly frequent at high latitudes, where the upper atmosphere is highly sensitive to perturbations coming from outer space. With the development of present and future low-frequency space-borne microwave missions (e.g., Soil Moisture and Ocean Salinity [SMOS], Aquarius, and Soil Moisture Active Passive missions), there is an increasing need to estimate the effects of the ionosphere on the propagation of electromagnetic waves that affects satellite measurements. As an example, how the TEC data collected at Concordia station are useful for the calibration of the European Space Agency SMOS data within the framework of an experiment promoted by the European Space Agency (known as DOMEX) will be discussed. The present report shows the ability of the GISTM station to monitor ionospheric scintillation and TEC, which indicates that only the use of continuous GPS measurements can provide accurate information on TEC variability, which is necessary for continuous calibration of satellite data.
    Description: Published
    Description: R0219
    Description: 1.7. Osservazioni di alta e media atmosfera
    Description: 1.10. TTC - Telerilevamento
    Description: 3.9. Fisica della magnetosfera, ionosfera e meteorologia spaziale
    Description: JCR Journal
    Description: open
    Keywords: Total electron content ; Antarctica ; GNSS ; GPS ; Faraday rotation ; Ionosphere ; 01. Atmosphere::01.02. Ionosphere::01.02.04. Plasma Physics ; 01. Atmosphere::01.02. Ionosphere::01.02.05. Wave propagation ; 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques ; 05. General::05.01. Computational geophysics::05.01.04. Statistical analysis ; 05. General::05.07. Space and Planetary sciences::05.07.02. Space weather
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 9
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    Examples of application of tensorial resistivity probability tomography to architectonic and archaeological targets (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: We present the results of the application of the tensor resistivity method to the assessment of the state of conservation of some architectonic features of the S.Giovanni a Carbonara monumental monastery (Naples, Italy) and to the recognition of buried remains in the archaeological site of the roman Port of Claudius at Fiumicino (Rome, Italy). The 3D tomographic approach, based on the concept of resistivity anomaly source occurrence probability, has been used for the analysis of the invariant parameter related to the trace of the determinant of the apparent resistivity tensor.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: applied geoelectrics– - tomography – cultural heritage ; apparent resistivity tensor ; probability ; tomography ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 10
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    Validation of a method for ionospheric electron density reconstruction by means of vertical incidence data during quiet and storm periods (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: A preliminary validation of the technique developed using the NeQuick ionospheric model and the «effective ionization parameter» Az, based on vertical total electron content data ingestion, was carried out in a previous study. The current study was performed to extend the analyzed conditions and confirm the results. The method to validate this technique is based on a comparison between hourly F2 peak values measured with Vertical Incidence (VI) soundings and those calculated with the new technique. Data corresponding to different hours and seasons (equinox, summer solstice, and winter solstice) during the period 2000-2003 (high and medium solar activity conditions) were compared for all available ionosonde stations. The results show a good agreement between foF2 and hmF2 values obtained with the new technique and measurements from vertical incidence soundings during quiet and storms conditions.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: electron density model ; vertical incidence ionograms ; ionospheric data ingestion ; 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 11
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    A model assisted ionospheric electron density reconstruction method based on vertical TEC data ingestion (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: A technique to reconstruct the electron density of the ionosphere starting from total electron content values has been developed using the NeQuick ionospheric electron density model driven by its effective ionization parameter Az. The technique is based on the computation of Az values for a suitable worldwide grid of points. A simple way to obtain relevant Az grids is to use global vertical Total Electron Content (TEC) maps to define for each grid point as Az value, the one that minimizes the difference between the experimental and the modeled vertical TEC. Having a global grid of Az values it is possible to compute the electron density at any point in the ionosphere using NeQuick. As a consequence, slant TEC values for specific ground station to satellite links or ionosphere peak parameter values at any location can be calculated. The results of the comparisons between experimental and reconstructed slant TEC as well as experimental and reconstructed peak parameters values indicate that the proposed reconstruction method can be used to reproduce the observed ionosphere in a realistic way.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: ionospheric data ingestion ; electrondensity model ; total electron content ; 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 12
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    Ionospheric biases correction for coordinates derived from GPS single point positioning (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: Most GPS users employ low cost receivers. These receivers do not allow users to record the pseudorange that they observe, but the computed coordinates. This work presents an original and simple method to correct ionospheric biases introduced in GPS signals. The originality of this method is based on the fact that no pseudorange is needed to correct the biases, only the calculated coordinates are used. This distinguishes this method from other classic alternatives. This paper evaluates the efficiency of the method with the use of real data.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: GNSS ; Global Positioning System ; singlepoint positioning ; ionospheric biases correction ; 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques ; 04. Solid Earth::04.03. Geodesy::04.03.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 13
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    Ionogram inversion F1-layer treatment effect in raytracing (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: This paper shows the importance of the F1-layer shape in the electron density profiles obtained from ionograms with different inversion techniques when the profiles are used in ray tracing. This layer often controls the propagation on the path with ranges less than about 2000 km, particularly for spring and summer periods. Ionograms from two different stations, Hainan (19.4N, 109E) and El Arenosillo (37.1N, -6.7E), obtained during the month of July 2002 (average sunspot number: 99.6) during geomagnetic quiet conditions (Ap-index between 9 and 15) are analyzed. The profiles obtained with two different inversion techniques with different options are used together with the ray tracing program of the Proplab-Pro software. This program calculates the features of the received signal as angle of arrival, path length, height of reflection and range for each given profile assumed to define a spherically symmetric ionosphere in the region along the path. For each ionospheric condition (location, day, hour) the difference between range values obtained with Proplab-Pro program using profiles from the two techniques and the different options (POLAN no valley, POLAN valley, POLAN1-layer and NHPC) are considered.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: raytracing ; F1 region ; electron densityprofile ; 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 14
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    Signal processing techniques for phase-coded HF-VHF radars (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: HF-VHF radar techniques are easy to employ and commonly used in geophysical applications. They include deep radio soundings, used for probing the ionosphere, stratosphere-mesosphere measurement, weather forecast and radio-glaciology. Fast algorithms and powerful processors facilitate the development of several kinds of low power radars, but the reduction of the transmitted power has to be compensated by on-line processing of an encoded signal to maintain a favorable signal-to-noise ratio suitable for detection. Moreover, radars have to reconstruct return echoes with different travel times due to various origins (multi-path, adjacent objects, etc.). Such needs can be accomplished by means of signal phase coding and one of the most attractive is the reversal phase code. The composite echo signal must be processed to extract the physical information useful for the measurement considered. In this paper some algorithms used for on-line processing of phase-coded signals will be described, both in time and frequency domain.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: phase-coded radar ; pulse compression ; signal integration ; 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 15
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    Can the polarization tagging of the ionogram trace deceive autoscaling methods? The Learmonth case (2008)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: This paper focuses on the problem of invalid O/X polarization tagging of an ionogram and how this can affect ionogram autoscaling methods. To illustrate this problem, 623 ionograms recorded in March and April 2004 (days 080-105) by the digisonde 256 installed at Learmonth (22.3° S, 114.1° E) were considered. These ionograms, often characterized by very unreliable O/X polarization tagging of the echoes because of unresolved antenna issues, have been autoscaled by both ARTIST 4.2 and Autoscala. Results of comparisons between automatically and manually scaled foF2 data are shown for both programs, considering as acceptable an autoscaled value that lies within 0.5 MHz of the manual value. Autoscala values of foF2 agree with the manually-scaled values for ~99% of ionograms, while ARTIST values of foF2 agree with the manually-scaled values for ~75% of ionograms. While ARTIST was coded on the assumption of valid polarization tagging, the fact remains that it produces invalid results when equipment issues cause invalid tagging. Autoscaling procedures that do not use the polarization tagging will generally work better than ARTIST in such cases. However, these other procedures are susceptible to failure in other situations.
    Description: Published
    Description: 597-607
    Description: 1.7. Osservazioni di alta e media atmosfera
    Description: 3.9. Fisica della magnetosfera, ionosfera e meteorologia spaziale
    Description: JCR Journal
    Description: open
    Keywords: Ionospheric Monitoring ; Ionograms ; ARTIST ; Autoscala ; 01. Atmosphere::01.02. Ionosphere::01.02.05. Wave propagation ; 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques
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  • 16
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    A scattering image of Campi Flegrei from the autocorrelation functions of velocity tomograms (2011)
    Wiley
    Details
    Publication Date: 2020-02-24
    Description: We propose a new quantitative approach for the joint interpretation of velocity and attenuation tomography images, performed through the lateral separation of scattering and intrinsic attenuation. The horizontal P-wave scattering attenuation structure below Campi Flegrei Caldera (CFC) is imaged using the autocorrelation functions (ACF) of P-wave vertical velocity fluctuations. Cluster analysis (CA) is then applied to interpret the images derived from ACF and the available P-wave total attenuation images at 2000m quantitatively. The analysis allows the separation of intrinsic and scattering attenuation on a 2-D plane, adding new geophysical constraints to the present knowledge about this volcanic area. The final result is a new, quantitative image of the past and present tectonic and volcanological state of CFC. P-wave intrinsic dissipation dominates in an area approximately located under the volcanic centre of Solfatara, as expected in a region with a large presence of fluids and gas. A north–south scattering attenuation region is mainly located below the zone of maximum uplift in the 1982–1984 bradiseismic crisis, in the sea side of the Pozzuoli bay, but also extending below Mt Nuovo. This evidence favours the interpretation in terms of a hard but fractured body, contoured by strong S-wave scatterers, corresponding to the Caldera rim: the region is possibly a section of the residual magma body, associated with the 1538 eruption of Mt Nuovo.
    Description: Published
    Description: 1304-1310
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: reserved
    Keywords: Probability distributions ; Seismic attenuation ; Seismic tomography ; Statistical seismology ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy
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  • 17
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    Severe magnetic storm effects in the ionosphere over Istanbul:a case study (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: The present study concentrates on the effects on the ionosphere of an individual severe magnetic Storm of the Sudden Commencement (SSC)type,with SSC taking place in the daytime hours.The storm started on 29 October 1968 and went on to 2 November 1968 with geomagnetic 3-hourly magnetic activity index reaching values of Kp 7. Interplanetary magnetic field polarities included A (field polarity Away from the solar wind)positive and T (field polarity Towards the solar wind)negative polarities.In these conditions,the local response of true height of F-region (hF) ionization fails nonlinearly from fixed plasma densities.The interplanetary B z ,the magnetic field H - component and K p were examined for the 5 days following the sudden commencement.Due to intensive geomagnetic SC effects,the lower and upper limits of the F -regions were unbalanced because of gravity relaxation and solar wind pressure effects,until normal levels were restored.In the F -layer 70%deviations of critical frequencies (f 0 F )from median values,as well as hF level variations reaching hundreds of kilometers,were observed and were responsible for the destruction of communication channels.With a plasmapause location value L =1.6 and with K p 7 the protonosphere reservoir should take 1.1 days for its replenishment;one day was in fact insufficient for a full plasma recovery.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: geomagnetic activity ; ionospheric positive storm ; neutral gas concentration excess ; radio reception ; ring current ; 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques ; 04. Solid Earth::04.05. Geomagnetism::04.05.08. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    The new AIS-INGV digital ionosonde (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: A new digital ionosonde called AIS-INGV (Advanced Ionospheric Sounder) was designed both for research and for routine service of HF radio wave propagation forecast. Nearly the entire system was developed in the Laboratorio di Geofisica Ambientale at the Istituto Nazionale di Geofisica e Vulcanologia (INGV), Rome. It exploits advanced techniques for signal analysis, recent technological devices and PC resources. This paper describes design concepts and performance of the new ionosonde.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: ionosonde ; pulse compression ; phase coherent integration ; 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    Real time monitoring for nowcasting and forecasting ionospheric space weatherin Europe with ground digisondes (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: The Earth's ionosphere largely determines space weather effects on radio wave communications, navigation and surveillance systems. Lately there has been an increasing demand for ionospheric nowcast and accurate forecast services by various groups of users, including European industry. The paper reviews research activities in Europe based on the exploitation of real-time ground digisondes for the provision of nowcasting and forecasting ionospheric space weather information and useful products and services to support operational applications. During the last few years, important progress in databasing, modelling and forecasting ionospheric disturbances based on real-time data from ground digisondes was achieved in the frames of COST Action 271 «Effects of the Upper Atmosphere on Terrestrial and Earth-Space Communications». Further developments are expected to be deployed with the new COST Action 724 on «Developing the basis for monitoring, modelling and predicting space weather», as well as through the Space Weather Pilot Project of the European Space Agency and through projects funded by the European Commission programmes.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: ionosphere ; ionospheric nowcasting ; ionospheric forecasting ; space weather ; ionogram scaling ; digisonde ; ionospheric monitoring networks ; 01. Atmosphere::01.02. Ionosphere::01.02.03. Forecasts ; 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques
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    Testing of the transionospheric radiochannel using data from the global GPS network (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: Using the international ground-based network of two-frequency receivers of the GPS navigation system provides a means of carrying out a global, continuous and fully-computerized monitoring of phase fluctuations of signals from satellite-borne radio engineering systems caused by the Earth's inhomogeneous and nonstationary ionosphere. We found that during major geomagnetic storms, the errors of determination of the range, frequency Doppler shift and angles of arrival of transionospheric radio signals exceeds that for magnetically quiet days by one order of magnitude as a minimum. This can be the cause of performance degradation of current satellite radio engineering navigation, communication and radar systems as well as superlong-baseline radio interferometry systems.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: total electron content ; GPS ; transionospheric radiochannel ; geomagnetic disturbances ; space weather ; 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    Geomagnetism and Aeronomy activities in Italy during IGY, 1957/58 (2009)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: In 2007 several events were organized to celebrate the fiftieth anniversary of the International Geophysical Year (IGY, 1957-1958). The celebrations will last until 2009 and are taking place within different contexts: the International Polar Year (IPY), the International Heliophysical Year (IHY), the electronic Geophysical Year (eGY) and the International Year of Planet Earth (IYPE). IGY offered a very appropriate and timely occasion to undertake a series of coordinated observations of various geophysical phenomena all over the globe. Italy took part in the broad international effort stimulated by IGY. In fact, Italy participated in observations and studies in many of the proposed scientific areas, in particular Geomagnetism and Aeronomy. The Istituto Nazionale di Geofisica (ING) started the installation of observatories, and updated and ensured continuous recording of geophysical observations. Geomagnetism, ionospheric physics, seismology, and other geophysical disciplines, were advanced. Although much of the work was undertaken in Italy, some attention was also devoted to other areas of the world, in particular Antarctica, where Italy participated in seismological observations. This paper gives a summary of the Geomagnetism and Ionospheric Physics activities within IGY. Furthermore, we highlight the importance of this historical event and its outcomes for the improvement of geophysical observations and the post-IGY growth of scientific investigations in Italy.
    Description: Published
    Description: 127 - 135
    Description: 1.6. Osservazioni di geomagnetismo
    Description: 1.7. Osservazioni di alta e media atmosfera
    Description: 3.9. Fisica della magnetosfera, ionosfera e meteorologia spaziale
    Description: JCR Journal
    Description: open
    Keywords: IGY ; Geomagnetism ; Aeronomy ; History of Geophisics ; Italy ; 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques ; 01. Atmosphere::01.03. Magnetosphere::01.03.99. General or miscellaneous ; 01. Atmosphere::01.03. Magnetosphere::01.03.06. Instruments and techniques ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous ; 05. General::05.03. Educational, History of Science, Public Issues::05.03.99. General or miscellaneous
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    Investigation into the problem of characterization of the HF ionospheric fluctuating channel of propagation: construction of a physically based HF channel simulator (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: A wideband HF simulator has been constructed that is based on a detailed physical model. It can generate an output giving a time realization of the HF wideband channel for any HF carrier frequency and bandwidth and for any given transmitter receiver path, time of day, month and year and for any solar activity/geomagnetic conditions. To accomplish this, a comprehensive solution has been obtained to the problem of HF wave propagation for the most general case of a 3D inhomogeneous ionosphere with time-varying electron density fluctuations. The solution is based on the complex phase method (Rytov s method), which has been extended to the case of an inhomogeneous medium and a point source of the field. Results of simulation obtained according to the technique developed have been presented, calculated for a single-hop path 1000 km long oriented to the south from St. Petersburg and including a horizontal electron density gradient present in the IRI model used as the basis of the ionosphere model. The fluctuations of the ionospheric electron density were characterized by an inverse power law anisotropic spatial spectrum. For this model, the random walk of the phasor at the receiver is determined and shown both for paths reflected in the E- and Fregions, being significantly larger for the latter. The oblique sounding ionogram is constructed and reveals three propagation modes: the E-mode and low and high angle F-mode paths. The time-varying field due to each of these paths is then summed at the receiving location enabling the calculation of the scattering function and also the time realization of the received signal shown as a function of both fast and slow time. This is performed both with and without the presence of the geomagnetic field; in the former case the splitting of the F2-mode into both e- and o-modes is seen. It is also shown how the scattering function can be obtained from the time realization of the channel in a way akin to experimental determination of the scattering function from channel measurements. Results from the simulations show the very significant effect of irregularities of even modest magnitude and the comparative effects due to background ionosphere dispersion and the fluctuating irregularities as well as geomagnetic mode splitting. Since the simulator is based on a physical model, it should be possible by comparison of experimental results and simulation to identify the correspondence between physical parameters (e.g., the variance and anisotropy of the electron density fluctuations, orientation of the propagation path to the magnetic meridian, bulk ionosphere motions) with observed channel parameters (e.g., Doppler spread and shift, time delay spread).
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques ; 05. General::05.09. Miscellaneous::05.09.99. General or miscellaneous
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    Relations between electron contentand peak density: regular and extreme behaviour (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: Electron content statistics offers important information for planning and operation of various application systems that make use of the transionospheric propagation of radio signals. Electron content statistics meet with an important difficulty: the majority of data stem from observations on the radio signals of orbiting satellites. The database for vertical electron content derived from observations of radio signals emitted from geostationary satellites is only very small. Therefore it is important to make use of statistics for peak density from ionosonde measurements. Quantile statistics do not contain information about ionization extremes. Therefore it is necessary to complement the statistics with case studies which reveal unusual and extreme electron content structures in space and in time.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    Behaviour of large scale structures of the electron content as a key parameterfor range errors in GNSS applications (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: The Total Electron Content (TEC) of the ionosphere is a key parameter for describing the ionospheric state. This paper deals with the large scale behaviour of TEC under low and high solar activity conditions. Large scale structures of the plasma density are formed by fundamental ionospheric processes mainly driven by solar radiation input, neutral winds and electric fields. The monitoring of large scale structures contributes to a comprehensive understanding of these coupling mechanisms which are rather complex particularly under perturbed geomagnetic conditions. The paper addresses techniques to monitor TEC with sufficient accuracy of a few TEC units (1016m-2) to measure large scale structures over Europe and over the polar areas. The availability of GPS data from global GPS receiver networks as e.g., those from the International GPS Service (IGS) is dense enough to generate TEC maps on a continuous base. A model assisted technique is briefly described for mapping TEC over the European and polar areas. A statistical estimation of horizontal TEC gradients reveals large scale gradients of up to about 6 TECU/1000 km under high solar activity conditions at an occurrence probability level of about 1%. Occasionally, during severe ionospheric storms this value may increase by a factor of 10 or even more. A close correlation of large scale gradients and the geomagnetic activity has been found giving the chance to forecast TEC gradient amplitudes by using predicted geomagnetic indices. Since TEC is proportional to first-order range errors in Global Satellite Navigation Systems (GNSS) such as the US GPS and the Russian GLONASS the study of the behaviour of this parameter has a practical meaning in GNSS based navigation and positioning. The paper addresses the close relationship between TEC and ranging errors in GNSS. Having in view Galileo, the planned Europes own global satellite navigation system, some aspects related to the mitigation of ionospheric propagation errors within the European Geostationary Navigation Overlay System (EGNOS) are discussed. Since EGNOS will augment the two above mentioned satellite navigation systems and make them suitable for safety critical applications such as flying aircraft or navigating ships through narrow channels the ionospheric propagation errors have to be mitigated as much as possible.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques
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    A way to increase the bit ratein ionospheric radio links (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: The aim of this paper is to present a high data rate transmission system through the ionospheric channel in the HF-band (3-30 MHz). The applications expected in this study are image transmitting and real-time videoconferencing. Very high rates are required compared to the standard modems. Therefore, an array processing is performed with a set of antennas whose spatial response differs from one another arranged in a circular array or in a collocated sensor. Synchronization (Zero Crossing Detector) and source separation (LMS algorithm) resort to classical well-tested techniques involving training sequences. Experimental results are presented for both antenna configurations. These techniques improve data rate, reaching 20 kbits/s within the 6 kHz bandwidth (QAM 64) without coding or interleaving.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    Integrated interpretation of seismic and resistivity images across the «Val d'Agri» graben (Italy) (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: Val d'Agri is a «recent SSW - NNE graben» located in the middle of the Southern Apennines thrust belt «chain» and emplaced in Plio-Pleistocene.The recent sedimentation of the valley represents a local critical geophysical problem. Several strong near surface velocity anomalies and scattering degrades seismic data in different ways and compromises the seismic visibility. In 1998, ENI and Enterprise, with the contribution of the European Community (ESIT R & D project - Enhance Seismic In Thrust Belt; EU Thermie fund) acquired two «experimental seismic and Resistivity lines» across the valley. The purpose of the project was to look for methods able to enhance seismic data quality and optimize the data processing flow for «thrust belt» areas. During the work, it was clear that some part of the seismic data processing flow could be used for the detailed geological interpretation of the near subsurface too. In fact, the integrated interpretation of the near surface tomography velocity/depth seismic section, built for enhancing the resolution of static corrections, with the HR resistivity profile, acquired for enhancing the seismic source coupling, allowed a quite detailed lithological interpretation of the main shallow velocity changes and the 2D reconstruction of the structural setting of the valley.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: ESIT project ; seismic imaging ; tomostatics ; integrated interpretations ; 04. Solid Earth::04.02. Exploration geophysics::04.02.06. Seismic methods ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy
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    Some considerations for different time-domain signal processing of pulse compression radar (2011)
    INGV
    Details
    Publication Date: 2017-04-04
    Description: Radar technology has for a long time used various systems that allow detection under high-resolution conditions, while emitting at the same time low peak power. Among these systems, transmitted pulse encoding by means of biphasic codes has been used for the advanced ionospheric sounder that was developed by the AIS-INGV ionosonde. In the receiving process, suitable decoding of the signal must be accomplished. This can be achieved in both the time and the frequency domains. Focusing on the time domain, different approaches are possible. In this study, two of these approaches have been compared, using data acquired by the AIS-INGV and processed by means of software tools (mainly Mathcad©). The analysis reveals the differences under both noiseless and noisy conditions, although this does not allow the conclusive establishment as to which method is better, as each of them has benefits and drawbacks.
    Description: Published
    Description: 1-11
    Description: 1.7. Osservazioni di alta e media atmosfera
    Description: JCR Journal
    Description: open
    Keywords: Complementary code ; Correlation ; Pulse compression ; Ionosphere ; Radar ; Time domain ; 01. Atmosphere::01.02. Ionosphere::01.02.99. General or miscellaneous ; 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques
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    Variation of the feedback coefficient with R12 and the geographic latitude in 1-h ahead forecast of f0 F2 (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: The «prediction» and «forecast» of the critical frequency of the F 2 layer (f0 F2 ) is an important issue for frequency planning in short wave radio communications. In this context, «prediction» is used for the determination of monthly median values of f0 F2 for each hour, while «forecast» denotes the determination of hourly values. In a previous paper we proposed a «sliding window» technique for prediction combined with «feedback» for forecast (Bilge and Tulunay, 2000). In the present paper we obtain the variation of the feedback coefficient with R 12 and geographic latitude.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: forecast ; feedback ; critical frequency ; 01. Atmosphere::01.02. Ionosphere::01.02.03. Forecasts ; 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    Nowcasting, forecasting and warning for ionospheric propagation: tools and methods (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: The paper reviews the work done in the course of the COST 271 Action concerned with the development of tools and methods for forecasting, nowcasting and warning of ionospheric propagation conditions. Three broad categories of work are covered. First, the maintenance and enhancement of existing operational services that provide forecast or nowcast data products to end users; brief descriptions of RWC Warsaw and the STIF service are given. Second, the development of prototype or experimental services; descriptions are given of a multi-datasource system for reconstruction of electron density profiles, and a new technique using real-time IMF data to forecast ionospheric storms. The third category is the most wide-ranging, and deals with work that has presented new or improved tools or methods that future operational forecasting or nowcasting system will rely on. This work covers two areas - methods for updating models with prompt data, and improvements in modelling or our understanding of various ionospheric-magnetospheric features - and ranges over updating models of ionospheric characteristics and electron density, modelling geomagnetic storms, describing the spatial evolution of the mid-latitude trough, and validating a recently-proposed technique for deriving TEC from ionosonde observations.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: 01. Atmosphere::01.02. Ionosphere::01.02.03. Forecasts ; 01. Atmosphere::01.02. Ionosphere::01.02.05. Wave propagation ; 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques
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    Earth modeling and estimation of the local seismic ground motion due to site geology in complex volcanoclastic areas (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: Volcanic areas often show complex behaviour as far as seismic waves propagation and seismic motion at surface are concerned. In fact, the finite lateral extent of surface layers such as lava flows, blocks, differential welding and/or zeolitization within pyroclastic deposits, introduces in the propagation of seismic waves effects such as the generation of surface waves at the edge, resonance in lateral direction, diffractions and scattering of energy, which tend to modify the amplitude as well as the duration of the ground motion. The irregular topographic surface, typical of volcanic areas, also strongly influences the seismic site response. Despite this heterogeneity, it is unfortunately a common geophysical and engineering practice to evaluate even in volcanic environments the subsurface velocity field with monodimensional investigation method (i.e. geognostic soundings, refraction survey, down-hole, etc.) prior to the seismic site response computation which in a such cases is obviously also made with 1D algorithms. This approach often leads to highly inaccurate results. In this paper we use a different approach, i.e. a fully 2D P-wave Çturning rayÈ tomographic survey followed by 2D seismic site response modeling. We report here the results of this approach in three sites located at short distance from Mt. Vesuvius and Campi Flegrei and characterized by overburdens constituted by volcanoclastic deposits with large lateral and vertical variations of their elastic properties. Comparison between 1D and 2D Dynamic Amplification Factor shows in all reported cases entirely different results, both in terms of peak period and spectral contents, as expected from the clear bidimensionality of the geological section. Therefore, these studies suggest evaluating carefully the subsoil geological structures in areas characterized by possible large lateral and vertical variations of the elastic properties in order to reach correct seismic site response curves to be used for engineering projects.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: dynamic amplification factor ; seismic ; tomography ; pyroclastic rocks ; finite element method ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy
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    Electon density profiles of the topside ionosphere (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: The existing uncertainties about the electron density profiles in the topside ionosphere, i.e., in the height region from h m F 2 to ~ 2000 km, require the search for new data sources. The ISIS and Alouette topside sounder satellites from the sixties to the eighties recorded millions of ionograms but most were not analyzed in terms of electron density profiles. In recent years an effort started to digitize the analog recordings to prepare the ionograms for computerized analysis. As of November 2001 about 350 000 ionograms have been digitized from the original 7-track analog tapes. These data are available in binary and CDF format from the anonymous ftp site of the National Space Science Data Center. A search site and browse capabilities on CDAWeb assist the scientific usage of these data. All information and access links can be found at http://nssdc.gsfc.nasa.gov/space/isis/isis-status. html. This paper describes the ISIS data restoration effort and shows how the digital ionograms are automatically processed into electron density profiles from satellite orbit altitude (1400 km for ISIS-2) down to the F peak. Because of the large volume of data an automated processing algorithm is imperative. The TOPside Ionogram Scaler with True height algorithm TOPIST software developed for this task is successfully scaling ~ 70% of the ionograms. An «editing process» is available to manually scale the more difficult ionograms. The automated processing of the digitized ISIS ionograms is now underway, producing a much-needed database of topside electron density profiles for ionospheric modeling covering more than one solar cycle.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: ionograms ; electron density profiles ; satellite orbits altitude ; 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques
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    Long-term trends in the ionosphere and upper atmosphere parameters (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: The first part of the paper is directed to the investigation of the practical importance of possible longterm trends in the F2-layer for ionospheric prediction models. Using observations of about 50 different ionosonde stations with more than 30 years data series of foF2 and hmF2, trends have been derived with the solar sunspot number R12 as index of the solar activity. The final result of this trend analysis is that the differences between the trends derived from the data of the individual stations are relatively large, the calculated global mean values of the foF2 and hmF2 trends, however, are relatively small. Therefore, these small global trends can be neglected for practical purposes and must not be considered in ionospheric prediction models. This conclusion is in agreement with the results of other investigations analyzing data of globally distributed stations. As shown with the data of the ionosonde station Tromsø, however, at individual stations the ionospheric trends may be markedly stronger and lead to essential effects in ionospheric radio propagation. The second part of the paper deals with the reasons for possible trends in the Earth’s atmo- and ionosphere as investigated by different methods using characteristic parameters of the ionospheric D-, E-, and F-regions. Mainly in the F2-region different analyses have been carried out. The derived trends are mainly discussed in connection with an increasing greenhouse effect or by long-term changes in geomagnetic activity. In the F1-layer the derived mean global trend in foF1 is in good agreement with model predictions of an increasing greenhouse effect. In the E-region the derived trends in foE and h´E are compared with model results of an atmospheric greenhouse effect, or explained by geomagnetic effects or other anthropogenic disturbances. The trend results in the D-region derived from ionospheric reflection height and absorption measurements in the LF, MF and HF ranges can at least partly be explained by an increasing atmospheric greenhouse effect.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques
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    Forecasting of ionospheric characteristics during quiet and disturbed conditions (2006)
    INGV
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    Publication Date: 2019-11-04
    Description: An autocovariance forecasting procedure for single location ionospheric characteristics is presented. Its accuracy is illustrated as a function of the amount of time extrapolation for selected European stations under quiet and disturbed conditions.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: Forecasting procedure ; 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques
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    Mathematical modeling to reconstruct Elastic and geoelectrical parameters (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: The monitoring of the underground medium requires estimation of accuracy of the methods used. Numerical simulation of the solution of 2D inverse problem on the reconstruction of seismic and electrical parameters of local (comparable in size with the wavelength) inhomogeneities by the diffraction tomography method based upon the first order Born approximation is considered. The direct problems for the Lame and Maxwell equations are solved by the finite difference method that allows us to take correctly into account the diffraction phenomenon produced by the target inhomogeneities with simple and complex geometry. For reconstruction of the local inhomogeneities the algebraic methods and the optimizing procedures are used. The investigation includes a parametric representation of inhomogeneities by the simple and complex functions. The results of estimation of the accuracy of the reconstruction of elastic inhomogeneities and inhomogeneities of electrical conductivity by the diffraction tomography method are represented.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: diffraction tomography ; mathematical modeling ; seismic tomography ; electromagnetic tomography ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy ; 05. General::05.05. Mathematical geophysics::05.05.99. General or miscellaneous
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    Association of Total Electron Content (TEC) and foF2 variations with earthquake events at the anomaly crest region (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: The paper attempts to identify ionospheric parameters in association with earthquake at anomaly crest station through VHF Radio Beacon data and ground based ionosonde measurements while the Total Electron Content(TEC) parameters from RB observations are based mainly on data taken over Guwahati (26.2°N, 91.75° E), foF2 data used in the analysis were collected at Ahmadabad (23.01°N, 72.36°E). The paper describes methods and techniques adopted to examine modifications on these parameters if any, due to earthquake preparatory processes at equatorial anomaly crest stations. The mechanism of inducement of density changes in the ionosphere is sought through the generation of strong fountain effect possibly by the development of electric field during the earthquake preparatory process.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: earthquake ; TEC ; foF2 ; anomaly ; 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques ; 04. Solid Earth::04.02. Exploration geophysics::04.02.06. Seismic methods ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    A dynamic system to forecast ionospheric storm disturbances based on solar wind conditions (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: For the reliable performance of technologically advanced radio communications systems under geomagnetically disturbed conditions, the forecast and modelling of the ionospheric response during storms is a high priority. The ionospheric storm forecasting models that are currently in operation have shown a high degree of reliability during quiet conditions, but they have proved inadequate during storm events. To improve their prediction accuracy, we have to take advantage of the deeper understanding in ionospheric storm dynamics that is currently available, indicating a correlation between the Interplanetary Magnetic Field (IMF) disturbances and the qualitative signature of ionospheric storm disturbances at middle latitude stations. In this paper we analyse observations of the foF2 critical frequency parameter from one mid-latitude European ionospheric station (Chilton) in conjunction with observations of IMF parameters (total magnitude, Bt and Bz-IMF component) from the ACE spacecraft mission for eight storm events. The determination of the time delay in the ionospheric response to the interplanetary medium disturbances leads to significant results concerning the forecast of the ionospheric storms onset and their development during the first 24 h. In this way the real-time ACE observations of the solar wind parameters may be used in the development of a real-time dynamic ionospheric storm model with adequate accuracy.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: inospheric forecasting ; ionospheric modelling ; ionospheric storms ; 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques
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    Imaging of the equatorial ionosphere (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: The equatorial anomaly is the dominant structure in free electron concentration in the tropical ionosphere. Due to its edges (crests) which are characterised by steep latitudinal gradients in TEC and are temporally and spatially variable, it is one of the ionospheric regions most difficult to image with inversion methods. In this paper we reconstruct an International Reference Ionosphere model of the equatorial ionosphere by employing a grid of virtual ground GPS receivers and actual GPS satellite positions. The MIDAS algorithm, an inversion method for reconstructing the ionosphere as a linear composition of given empirical orthogonal functions, is used. Comparing the true model ionosphere with the resulting images a fine tuning of the basis functions (vertical profile contraints) in the inversion is realised.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: atmosphere ; electromagnetic methods ; remote sensing ; tomography ; data processing ; GPS TEC ; 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    Ionospheric storm forecasting technique by artificial neural network (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: In this work we further refine and improve the neural network based ionospheric characteristic's foF2 predictor, which is actually a neural network autoregressive model with additional input signals (NNARX). Our analysis is focused on choice of X parts of NNARX model in order to capture middle and long term dependencies. Daily distribution of prediction error suggests need for structural changes of the neural network model, as well as adaptation of running average lengths used for determination of X inputs. Generalisation properties of proposed neural predictor are improved by carefully designed pruning procedure with additional regularisation term in criterion function. Some results from the NNARX model are presented to illustrate the feasibility of using such a model as ionospheric storm forecasting technique.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: prediction and forecasting ; neural networks ; ionospheric storms modelling ; space weather ; 01. Atmosphere::01.02. Ionosphere::01.02.03. Forecasts ; 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques
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    A three-dimensional time-dependent algorithm for ionospheric imaging using GPS (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: Global Positioning System (GPS) satellite receivers provide a world-wide network of phase and group delay measurements. The combination of two-frequency measurements can be used to derive the integral of the electron concentration along each satellite-to-receiver path, a parameter known as the Total Electron Content (TEC). At this stage these slant TEC data are diffi cult to interpret as they originate from a combination of a temporally changing ionosphere and spatially changing observation geometry. In this paper TEC data are inverted to evaluate the underlying distribution and time evolution of electron concentration. Accordingly, a new three-dimensional, time-dependent algorithm is presented here for imaging ionospheric electron concentration using GPS signals. The inversion results in a three-dimensional movie rather than a static image of the electron-concentration distribution. The technique is demonstrated using simulated ground-based GPS data from actual measurement geometry over Europe.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: ionosphere ; imaging ; GPS ; inversion ; tomography ; 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques ; 05. General::05.01. Computational geophysics::05.01.05. Algorithms and implementation
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    Shear-velocity andi anisotropy structure of a retreating extensional forearc (Tuscany, Italy) from receiver functions inversion (2011)
    Wiley
    Details
    Publication Date: 2017-04-04
    Description: We investigate in detail the crustal layering of the ‘Val di Chiana Basin’ (Northern Apennines, Tuscany, Italy) through receiver functions and seismic anisotropy with hexagonal symmetry. The teleseismic data set is recorded in correspondence of a typical foreland basin resulting by the progressive eastward retreat of a regional-scale subduction zone trapped between two continents. We study the azimuthal variations of the computed and binned receiver functions associated to a harmonic angular analysis to emphasize the presence of the dipping and the anisotropic structures. The resulting S-wave velocity model shows interesting and new results for this area that we discuss in a regional geodynamic contest contributing to the knowledge of the structure of the forearc of the subduction zone. A dipping interface (N192°E strike, 18° dip) has been revealed at about 1.5 km depth, that separates the basin sediments and flysch from the carbonates and evaporites. Moreover, we interpret the two upper-crust anisotropic layers (at about 6 and 17 km depth) as the Hercynian Phyllites and Micaschists, of the Metamorphic Tuscan Basement. At relatively shallow depths, the presence of these metamorphic rocks causes the seismic anisotropy in the upper crust. The presence of shallow anisotropic layers is a new and interesting feature, first revealed in the study area. Beneath the crust–mantle transition (Moho), located about 28 km depth, our analysis reveals a 7-km-thick anisotropic layer.
    Description: Published
    Description: 545-556
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: reserved
    Keywords: Seismic anisotopy ; Computational Seismology ; Wave propagation ; Subduction zone process ; Crustal structure ; Europe ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy
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    Detection of meteorological inconsistencies by GPS (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: GPS observations, distances from satellites to receivers and meteorological conditions in neutral atmosphere are known to obey a constraint, which provides a residual or in other words a quality index. A method is discussed which provides a residual epoch by epoch in near real time. In general, distribution of residuals during several consecutive epochs belonging to the same satellites, allows estimates of a mean and a standard deviation of mean. Under normal meteorological conditions distribution of residuals appears to be consistent with zero mean as expected. However, consecutive residuals sometimes appear to have a mean different from zero by more than three standard deviations of mean. Such signifi cant consecutive epochs provide a warning of existing inconsistencies among GPS observations, distances from satellites to receivers as obtained by orbital information, meteorological conditions above receivers (as obtained by ground measurements or by extrapolation of meteorological analysis). A procedure has been set up which warns about these inconsistencies in near real time.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: GPS ; double difference ; zenith totaldelay ; residuals ; 01. Atmosphere::01.01. Atmosphere::01.01.08. Instruments and techniques ; 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques ; 04. Solid Earth::04.03. Geodesy::04.03.09. Instruments and techniques
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    Radio occultation techniques for probing the ionosphere (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: GPS radio occultation measurements establish the basis for a new remote sensing technique for vertical profile information on the electron density of the entire ionosphere from satellite orbit heights down to the bottomside. No other profiling technique such as vertical sounding or incoherent scatter, unifies vertical profiling through the entire ionosphere with global coverage. Inversion methods are described both for vertical profiling as well as for tree dimensional electron density reconstructions of the ionosphere. In three dimensional electron density reconstructions using signals from Global Navigation Satellite Systems (GNSS), the Ionospheric Radio Occultation (IRO) measurements provide vertical information which is complementary to the information obtained by ground based measurements. Assessment of achievable accuracy and spatial resolution are addressed by simulation studies. IRO measurements have been carried out onboard the German CHAMP satellite since 11 April 2001 on a routine basis. Assuming a spherically layered ionosphere, up to about 150 Electron Density Profiles (EDPs) per day are retrieved within a latency of 3 h. Validation results obtained by using independent data sources are reported. The validation with vertical sounding data in mid-latitudes indicates a small positive bias in the plasma frequency of up to about 0.5 MHz throughout the entire profile. Averages of the numerous EDPs show wellknown ionospheric phenomena such as the equatorial anomaly, the winter anomaly and the expansion of the profile with increasing solar energy input. It is concluded that CHAMP-IRO measurements have the potential to establish global data sets of vertical electron density profiles for developing and improving global ionospheric models and to provide operational space weather information.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques
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    Climatology of ionosphericF-region disturbances (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: After more than 60 years of research, ionospheric disturbances are today a most challenging topic of upper atmospheric physics. Although the understanding of the thermosphere-ionosphere system has increased, quantitative predictions of ionospheric perturbations, valid for space weather assessment, are still imprecise. Using a long foF2 dataset, an analytical climatology of the F-region storms is presented as a function of appropriate variables. Local phenomena are then detected.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: ionosphere ; F2-layer critical frequency ; ionospheric disturbances ; 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques ; 05. General::05.02. Data dissemination::05.02.05. Collections
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    Software for the automatic scaling of critical frequency f0F2 and MUF(3000) F2 from ionograms appliedat the Ionospheric Observatory of Gibilmanna (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: Software for the automatic scaling of critical frequency f0F2 and MUF(3000)F2 from ionograms was developed and applied to the ionograms produced by the new Advanced Ionospheric Sounder installed at the Ionospheric Observatory of Gibilmanna. A test based on 1124 ionograms recorded in normal ionospheric condition was performed comparing the automatically scaled parameters with the corresponding ones obtained by the standard manual method. The results of a preliminary test performed during a strong magnetic ionospheric storm are also presented.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: ionograms ; automatic scaling ; ionosonde ; 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    Surface wave dispersion measurements from ambient seismic noise analysis in Italy (2011)
    Wiley
    Details
    Publication Date: 2017-04-04
    Description: We present the surface wave dispersion results of the application of the ambient noise method to broad-band data recorded at 114 stations from the Istituto Nazionale di Geofisica e Vul- canologia (INGV) national broad-band network, some stations of the Mediterranean Very Broadband Seismographic Network (MedNet) and of the Austrian Central Institute for Me- teorology and Geodynamics (ZAMG). Vertical-component ambient noise data from 2005 October to 2007 March have been cross-correlated for station-pairs to estimate fundamental mode Rayleigh wave Green’s functions. Cross-correlations are calculated in 1-hr segments, stacked over periods varying between 3 months and 1.5 yr. Rayleigh wave group dispersion curves at periods from 8 to 44 s were determined using the multiple-filter analysis technique. The study region was divided into a 0.2◦ × 0.2◦ grid to invert for group velocity distribu- tions. Checkerboard tests were first carried out, and the lateral resolution was estimated to be about 0.6◦. The resulting group velocity maps from 8 to 36 s show the significant difference of the crustal structure and good correlations with known geological and tectonic features in the study region. The Po Plain and the Southern Alps evidence lower group veloci- ties due to soft alluvial deposits, and thick terrigenous sediments. Our results also clearly showed that the Tyrrhenian Sea is characterized with much higher velocities below 8 km than the Italian peninsula and the Adriatic Sea which indicates a thin oceanic crust beneath the Tyrrhenian Sea.
    Description: Published
    Description: 1242-1252
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: reserved
    Keywords: Tomography ; Surface waves and free oscillations ; Crustal structure ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy
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    Ionosphere-plasmasphere response to geomagnetic storms studied with the RMI-Dourbes comprehensive database (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: Presented is a review of the ionospheric storm research carried out at the Royal Meteorological Institute (RMI)of Belgium.The studies are based on the opportunities offered by the long-term measurements and the accumulated comprehensive database managed by the RMI Geophysics Centre at Dourbes (4.6 °E,50.1 °N).Reported are case studies of major storms,and also results in developing forecasting and density reconstruction methods.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: ionospheric storms ; synthetic geomagnetic index ; electron profile reconstruction ; 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    Depression of the ULF geomagnetic pulsation related to ionospheric irregularities (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: We consider a depression in intensity of ULF magnetic pulsations, which is observed on the ground surface due to appearance of the irregularities in the ionosphere. It is supposed that oblique Alfven waves in the ULF frequency range are downgoing from the magnetosphere and the horizontal irregularities of ionospheric conductivity are created by upgoing atmospheric gravity waves from seismic source. Unlike the companion paper by Molchanov et al. (2003), we used a simple model of the ionospheric layer but took into consideration the lateral inhomogeneity of the perturbation region in the ionosphere. It is shown that ULF intensity could be essentially decreased for frequencies f = 0.001-0.1 Hz at nighttime but the change is negligible at daytime in coincidence with observational results.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: ULF ; ionosphere ; Alfven ; seismicity ; 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques ; 05. General::05.05. Mathematical geophysics::05.05.99. General or miscellaneous
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    Nowcasting, forecasting and warning for ionospheric propagation: supporting databases (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: The use of data is essential in the context of nowcasting, forecasting and warning of ionospheric propagation conditions, with roles to play in the development, evaluation and operation of models and services. Descriptions are given of three databases that have been established in the course of the COST 271 Action: a database of prompt ionospheric soundings, an extension to a database generated by the EISCAT incoherent scatter radars, and a database intended to facilitate evaluation of TEC estimation methods. Each database includes some background information, a description of the contents and interface, and instructions as to how to gain access to it.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: 01. Atmosphere::01.02. Ionosphere::01.02.05. Wave propagation ; 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques
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    Total electron content - A key parameterin propagation: measurement and usein ionospheric imaging (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: The paper reports on a series of studies carried out within the COST 271 Action relating to the measurement and use of Total Electron Content (TEC) of the ionosphere over North West Europe. Total electron content is a very important parameter for the correction of propagation effects on applied radio systems so that it is vital to have confidence in the experimental measurements and the resultant products derived as aids for the practical user. Comparative investigations have been carried out using TEC values from several different sources. It was found that in general there was broad statistical agreement between the data sets within the known limitations of the techniques, though discrepancies were identified linked to steep ionospheric gradients at the onset of geomagnetic storm disturbance and in the vicinity of the main trough. The paper also reviews recent progress in the development of tomographic inversion techniques that use total electron content measurements to image the ionosphere as an aid to various radio systems applications.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques
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    A revised method to extract thermospheric parameters from incoherent scatter observations (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: Height distribution of ionospheric plasma parameters in the F2-region is closely related to height distribution of the main thermospheric parameters. Therefore, they can be extracted from ionospheric observations solving an inverse problem of aeronomy. A self-consistent approach to the Ne(h) modeling at the F2-region heights has been applied to solve the problem. Using routine incoherent scatter radar observations (Ne(h), Te(h), Ti(h), Vi(h) profiles) the method yields a self-consistent set of main aeronomic parameters responsible for the F2-region formation. The list of derived parameters includes: neutral temperature profile Tn(h) depending on the exospheric temperature Tex, the temperature at 120 km T120 and the shape-parameter S, which determine the temperature profile, concentration of neutral species [O], [O2], [N2], vertical plasma drift W, which may be converted to the meridional thermospheric wind Vnx, total solar EUV flux and ion composition (O+, O2 +, NO+, N2 +, N+) as a result of Ne(h) fitting. Therefore, the method gives a complete description of the upper atmosphere condition in the vicinity of incoherent scatter facility for the periods of observation. Analysis of all available EISCAT (CP-1, CP-2) observations has shown wide deviations from MSIS-86 model predictions for geomagnetically disturbed conditions while the retrieved parameters are close to the model ones for quiet periods. The approach turns out to be very useful for physical analyses of the F2-layer disturbance mechanisms giving a complete picture of the phenomenon in question. Limitations and problems related to method application are discussed. Under existing conditions when thermospheric observations are not conducted currently the proposed method may be considered a real tool for thermosphere investigation and monitoring at least for the periods of ISR observations.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques
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    Development of algorithms and software for forecasting, nowcasting and variability of TEC (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: Total Electron Content (TEC) is an important characteristic of the ionosphere relevant to communications. Unpredictable variability of the ionospheric parameters due to various disturbances limits the efficiencies of communications, radar and navigation systems. Therefore forecasting and nowcasting of TEC are important in the planning and operation of Earth-space and satellite-to-satellite communication systems. Near-Earth space processes are complex being highly nonlinear and time varying with random variations in parameters where mathematical modeling is extremely difficult if not impossible. Therefore data driven models such as Neural Network (NN) based models are considered and found promising in modeling such processes. In this paper the NN based METU-NN model is introduced to forecast TEC values for the intervals ranging from 1 to 24 h in advance. Forecast and nowcast of TEC values are also considered based on TEC database. Day-to-day and hour to-hour variability of TEC are also estimated using statistical methods. Another statistical approach based on the clustering technique is developed and a preprocessing approach is demonstrated for the forecast of ionospheric critical frequency foF2.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques ; 05. General::05.01. Computational geophysics::05.01.05. Algorithms and implementation
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    Effects of gradients of the electron density on Earth-space communications (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: This paper is a review of the main results achieved in the framework of COST 271 Action Working Group 4, under the activities of the Work Package 4.4. The first topic treated deals with the influence of ionospheric space and time gradients in the slant to vertical and vertical to slant ionospheric delay conversion when the thin shell approximation of the ionosphere is assumed and with the effects of geomagnetic activity on the errors that this conversion introduces. The second topic is related to the comparison of ionospheric topside models with experimental electron density profiles to check the ability of the models to reproduce the observed topside shape and characteristics that determine the electron density gradients. The analysis that has been done allows pointing out the changes needed to improve the models. Finally a third topic covers a model simulation study of the total electron content that can be encountered in GPS-to-geostationary satellite ray paths. It takes into account that the propagation paths for such satellite-to-satellite links are very long and they have the potential to intersect regions of the ionised atmosphere where the electron density is high when the geometry is close to eclipse.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques
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    Emission Fourier transform spectroscopy for remote sensingof the Earth's atmosphere (2006)
    INGV
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    Publication Date: 2019-11-04
    Description: Fourier transform emission spectroscopy can make an important contribution in the observation of the Earth's atmosphere and in the investigation of atmospheric physics and chemistry. In this paper, we report the measurement performances and the result obtained by a Fourier transform spectrometer, named SAFIRE-A (Spectroscopy of the Atmosphere using Far Infrared Emission - Airborne), operating in the far infrared spectral region from limb sounding observation of the atmospheric emission from a high altitude aircraft. After a short review of the advantages of FTS emission limb sounding in comparison with competing techniques and observation geometries, a detailed description of the instrument is given with the result obtained during the APE-GAIA (Airborne Polar Experiment - Geophysica Aircraft In Antarctica) fi eld campaign carried out over the Antarctic Peninsula.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: Fourier transform spectroscopy ; emissionspectroscopy ; Earth observation ; stratospheric chemistry ; 01. Atmosphere::01.01. Atmosphere::01.01.08. Instruments and techniques ; 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 54
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    Mapping plasma structures in the high-latitude ionosphere using beacon satellite, incoherent scatter radar and ground-based magnetometer observations (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: In the autumn of the year 2000, four radio receivers capable of tracking various beacon satellites were set up along the southwestern coast of Greenland. They are used to reconstruct images of the ionospheric plasma density distribution via the tomographic method. In order to test and validate tomographic imaging under the highly variable conditions often prevailing in the high-latitude ionosphere, a time interval was selected when the Sondrestrom incoherent scatter radar conducted measurements of the ionospheric plasma density while the radio receivers tracked a number of beacon satellites. A comparison between two-dimensional images of the plasma density distribution obtained from the radar and the satellite receivers revealed generally good agreement between radar measurements and tomographic images. Observed discrepancies can be attributed to F region plasma patches moving through the field of view with a speed of several hundred meters per second, thereby smearing out the tomographic image. A notable mismatch occurred around local magnetic midnight when a magnetospheric substorm breakup occurred in the vicinity of southwest Greenland (identified from ground-based magnetometer observations). The breakup was associated with a sudden intensification of the westward auroral electrojet which was centered at about 69 and extended up to some 73 corrected geomagnetic latitude. Ground-based magnetometer data may thus have the potential of indicating when the tomographic method is at risk and may fail. We finally outline the application of tomographic imaging, when combined with magnetic field data, to estimate ionospheric Joule heating rates.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: Beacon satellites ; ionospheric plasma ; 01. Atmosphere::01.02. Ionosphere::01.02.04. Plasma Physics ; 01. Atmosphere::01.02. Ionosphere::01.02.05. Wave propagation ; 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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    New low power pulse compressed ionosonde at Gibilmanna Ionospheric Observatory (2006)
    INGV
    Details
    Publication Date: 2022-02-02
    Description: A digital low power pulse compressed ionosonde was developed at the Istituto Nazionale di Geofisica e Vulcanologia (INGV), Rome, Italy. The aim of this Advanced Ionospheric Sounder, AIS-INGV, is to reduce the transmitted power and, consequently, weight, size, power consumption and hardware complexity. To compensate the power reduction the most advanced HF radar techniques such as the pulse compression and a phase coherent integration are used. The ionosonde is completely programmable and a PC supports the data acquisition, control, storage and on-line processing. The first prototype was installed at Gibilmanna Ionospheric Observatory (Sicily), an interesting location in the center of Mediterranean area. The new ionosonde will contribute to ionospheric database and real time knowledge of South European ionospheric conditions for space weather applications. In this work the first results (ionograms and autoscaled characteristics) are presented and briefly discussed.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: ionosonde ; automatic ionogram scaling ; ionospheric data ; vertical soundings ; 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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