Beacon Satellite Symposium: Session 5B - June 30th 2016: Radio Occultation Techniques and Measurements

During the Beacon Satellite Symposium, held in Trieste, Italy, between June 26 and July 1 2016, the JRC chaired the session 5B: Radio Occultation Techniques and Measurements. The corresponding abstract of the session is provided as follows: Since the mid-1960s, the GNSS based radio occultation technique has been used to study the structure and properties of the atmospheres of not only Earth but also other planets, such as Venus, Mars, some other outer planets, and many of their moons. By measuring the phase delay of radio waves from GNSS satellites as they are occulted by the Earth’s atmosphere, the vertical density profiles of the bending angles of radio wave trajectories can be estimated using measurements onboard LEO satellites. The success of the GPS/MET mission in 1995 inspired a number of follow‐on missions that include radio occultation experiment, including the CHAMP, GRACE, SAC-C, COSMIC, Metop-A/B, C/NOFS, and upcoming COSMIC-2 satellites. The combined profiles from these different LEO satellites provide excellent opportunities to explore the dynamics and structure of the ionosphere, especially in the regions that have been devoid of ground-based instruments, allowing for investigation of the longitudinal variability of the ionospheric density structure. This session seeks contributions that advance the application of RO technique for space weather studies. In addition, we welcome presentations exploring innovative methodologies that address the current problem on RO inversion technique at the equatorial region where ionospheric irregularity, such as sporadic E and spread F, present and degrade the linear combination technique that affect the quality of density profile extracted in the region. The session was organized among Endawoke Yizengaw (Institute for Scientific Research, Boston College), Jann-Yenq Liu (National Space Organization –NSPO- Chief Scientist), and Angela Aragon-Angel (Joint Research Centre). The session consisted of both oral and poster presentation parts. This document presents the process of the session preparation within the Beacon Satellite Symposium organization. Moreover, the abstracts of the different contributions accepted to the session are also included for completeness.JRC.E.2-Technology Innovation in Securit

A three-dimensional regional assimilative model of the ionospheric electron density

The focus of this thesis is on the development, implementation, and validation of a three-dimensional regional assimilative model of the ionospheric electron density. Empirical climatological models, like the International Reference Ionosphere (IRI) model (Bilitza et al. 2017), cannot predict the whole ionospheric variability, specifically under disturbed magnetic conditions. The model presented in this work has the purpose to improve the IRI description by implementing a data assimilation procedure, based on ionospheric measurements collected by several ground-based or satellite-based instruments. The first phase of the development of the model, called IRI UPdate (IRI UP), is devoted to update the IRI model by ingesting effective indices (IG12eff and R12eff) calculated after assimilating F2 layer characteristics values, measured by a network of ionosondes or derived by vertical total electron content values measured by a network of Global Navigational Satellite Systems receivers. The ingestion of effective indices in the IRI model allows to significantly improve the F2 layer peak density and height description. Being the F2 layer peak an anchor point for the whole IRI’s vertical electron density profile, such procedure allows to update the whole profile. The second phase of the development of the model is devoted to improve the modeling of the topside part of the ionospheric vertical electron density profile by making use of the IRI UP method and in-situ measurements collected by Swarm satellites. Finally, a procedure called IonoPy, embedding the two aforementioned steps, assimilates the whole bottomside electron density profile measured by an ionosonde, thus further improving the ionospheric plasma description in the bottomside ionosphere. All the procedures described in this thesis have been tested and validated by comparing them with other similar models or with independent datasets, for both quiet and disturbed conditions

A Comparison of Sporadic-E Occurrence Rates Using Ionosondes and GPS Radio Occultation Measurements

Sporadic-E (Es) occurrence rates from Global Position Satellite radio occultation (GPS-RO) measurements have shown to vary by nearly an order of magnitude between studies, motivating a comparison with ground-based measurements. In an attempt to find an accurate GPS-RO technique for detecting Es formation, occurrence rates derived using five previously developed GPS-RO techniques are compared to ionosonde measurements over an eight-year period from 2010-2017. GPS-RO measurements within 170 km of a ionosonde site are used to calculate Es occurrence rates and compared to the ground-truth ionosonde measurements. Each technique is compared individually for each ionosonde site and then combined to determine the most accurate GPS-RO technique for binary (present or absent) Es measurements. Overall, the Yu et al. (2020) S4 method showed the closest agreement with ionosonde measurements between 2010-2017and is the recommended technique for future GPS-RO based Es climatologies

Imaging ionospheric irregularities by earth observation radar satellite

The sensitivity of Synthetic Aperture Radar (SAR) satellite signal in the L-band to ionospheric plasma density is used to obtain two-dimensional imaging of ionospheric density irregularities. As an application for equatorial ionosphere, we have recently reported first simultaneous observation of equatorial plasma bubble by the ALOS-2/PALSAR-2 satellite and a ground 630-nm airglow imager in northern Brazil. In this case, SAR ionospheric scintillation are represented as stripe-like signature of radar image over the terrain along the local magnetic field lines near an airglow depletion region. This so-called SAR scintillation stripes are discussed to be the signature of existing small-scale plasma irregularities with the scale size of hundreds of meters associated with equatorial plasma bubbles. We present the observational setup and the interpretation of SAR signal parameters to characterize the two-dimensional ionospheric density structures, and discuss future studies

Towards a more efficient spectrum usage: spectrum sensing and cognitive radio techniques

The traditional approach of dealing with spectrum management in wireless communications has been through the definition on a license user granted exclusive exploitation rights for a specific frequency.Peer ReviewedPostprint (published version

Abstracts on Radio Direction Finding (1899 - 1995)

The files on this record represent the various databases that originally composed the CD-ROM issue of "Abstracts on Radio Direction Finding" database, which is now part of the Dudley Knox Library's Abstracts and Selected Full Text Documents on Radio Direction Finding (1899 - 1995) Collection. (See Calhoun record https://calhoun.nps.edu/handle/10945/57364 for further information on this collection and the bibliography). Due to issues of technological obsolescence preventing current and future audiences from accessing the bibliography, DKL exported and converted into the three files on this record the various databases contained in the CD-ROM. The contents of these files are: 1) RDFA_CompleteBibliography_xls.zip [RDFA_CompleteBibliography.xls: Metadata for the complete bibliography, in Excel 97-2003 Workbook format; RDFA_Glossary.xls: Glossary of terms, in Excel 97-2003 Workbookformat; RDFA_Biographies.xls: Biographies of leading figures, in Excel 97-2003 Workbook format]; 2) RDFA_CompleteBibliography_csv.zip [RDFA_CompleteBibliography.TXT: Metadata for the complete bibliography, in CSV format; RDFA_Glossary.TXT: Glossary of terms, in CSV format; RDFA_Biographies.TXT: Biographies of leading figures, in CSV format]; 3) RDFA_CompleteBibliography.pdf: A human readable display of the bibliographic data, as a means of double-checking any possible deviations due to conversion

Proceedings of the fifth annual NASA and Department of Defense Precise Time and Time Interval Planning Meeting

Subjects covered at this meeting were navigation, communications, applications of interferometry, frequency and time standards and synchronization, and radio wave propagation