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  • 1
    Publication Date: 2022-09-22
    Description: Based on the analysis of electron density Ne profiles (Grahamstown ionosonde), a case study of the height‐dependent ionospheric response to two 27‐day solar rotation periods in 2019 is performed. A well‐defined sinusoidal response is observed for the period from 27 April 2019 to 24 May 2019 and reproduced with a Thermosphere‐Ionosphere‐Electrodynamics General Circulation Model simulation. The occurring differences between model and observations as well as the driving physical and chemical processes are discussed based on the height‐dependent variations of Ne and major species. Further simulations with an artificial noise free sinusoidal solar flux input show that the Ne delay is defined by contributions due to accumulation of O+ at the Ne peak (positive delay) and continuous loss of O2+ in the lower ionosphere (negative delay). The neutral parts' 27‐day signatures show stronger phase shifts. The time‐dependent and height‐dependent impact of the processes responsible for the delayed ionospheric response can therefore be described by a joint analysis of the neutral and ionized parts. The return to the initial ionospheric state (and thus the loss of the accumulated O+) is driven by an increase of downward transport in the second half of the 27‐day solar rotation period. For this reason, the neutral vertical winds (upwards and downwards) and their different height‐dependent 27‐day signatures are discussed. Finally, the importance of a wavelength‐dependent analysis, statistical methods (superposed epoch analysis), and coupling with the middle atmosphere is discussed to outline steps for future analysis.
    Description: Key Points: A response to solar 27‐day signatures is observed in ionosonde Ne height profiles and successfully reproduced with a Thermosphere‐Ionosphere‐Electrodynamics General Circulation Model simulation. Height‐dependent variations of the delayed ionospheric response are driven by the respective contributions of O+ and O2+. Transport processes have a significant impact on the 27‐day signatures of neutral and ionized parts in the upper atmosphere.
    Keywords: ddc:538.7 ; ddc:551.5
    Language: English
    Type: doc-type:article
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  • 2
    Publication Date: 2024-05-23
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉To understand the global response of thermospheric‐ionospheric (TI) parameters to variations in solar irradiance measurements from the Global‐Scale Observations of the Limb and Disk (GOLD) ultraviolet imaging spectrograph, solar radio flux F10.7, predictions from the Coupled Thermosphere Ionosphere Plasmasphere electrodynamics (CTIPe) model, and International Global Navigation Satellite System Service total electron content maps (TEC) have been used. Various parameters such as GOLD 〈italic〉O〈/italic〉/〈italic〉N〈/italic〉〈sub〉2〈/sub〉, 〈italic〉O〈/italic〉〈sub〉2〈/sub〉, and the nighttime peak electron density (Nmax) have been compared with the CTIPe model simulations. The GOLD observed Nmax shows a number of significant features including a winter anomaly and an equatorial ionization anomaly. The comparison with solar proxies showed that the GOLD 〈italic〉Q〈/italic〉〈sub〉〈italic〉EUV〈/italic〉〈/sub〉 correlates very well with the EUV observations compared to the F10.7 index. The study also examined the relationship between the solar proxies and Nmax on different time scales and found that Nmax responded significantly to 〈italic〉Q〈/italic〉〈sub〉〈italic〉EUV〈/italic〉〈/sub〉 at both medium‐ and long‐term timescales. Furthermore, a low correlation between Nmax in the equatorial region and solar proxies was found. A delayed ionospheric TEC response against solar flux variations within the 27‐day solar rotation was investigated. This ionospheric delay of TEC with respect to solar flux was observed to be less than 1 day, which was reproduced in model simulations. The current study has shown that the GOLD observations can be used to investigate the delayed ionospheric response and to gain a better understanding of the influence of solar activity on the TI system.〈/p〉
    Description: Key Points: 〈list list-type="bullet"〉 〈list-item〉 〈p xml:lang="en"〉Ionospheric‐thermospheric parameters observed by Global‐Scale Observations of the Limb and Disk (GOLD) ultraviolet imaging spectrograph are compared with Coupled Thermosphere Ionosphere Plasmasphere electrodynamics model simulations〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉The delayed ionospheric response against the solar flux is less than 1 day at the time scale of the 27 days solar rotation period〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉The integrated 1–45 nm solar energy flux values observed by GOLD correlate well with the F10.7 and EUV〈/p〉〈/list-item〉 〈/list〉 〈/p〉
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: http://cddis.nasa.gov/Data_and_Derived_Products/GNSS/atmospheric_products.html
    Description: http://gold.cs.ucf.edu/search/
    Description: https://omniweb.gsfc.nasa.gov/form/dx1.html
    Description: https://lasp.colorado.edu/lisird/
    Description: http://guvitimed.jhuapl.edu/data/products
    Description: https://doi.org/10.5281/zenodo.8145356
    Keywords: ddc:538.7 ; CTIPe model ; O/N2 ratio ; ionospheric delay ; solar activity ; thermosphere‐ionosphere ; GOLD
    Language: English
    Type: doc-type:article
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  • 3
    Publication Date: 2021-06-07
    Description: ESPAS, the ‘‘near-Earth space data infrastructure for e-science” is a data e-infrastructure facilitating discovery and access to observations, ground-based and space borne, and to model predictions of the near-Earth space environment, a region extending from the Earth’s atmosphere up to the outer radiation belts. ESPAS provides access to metadata and/or data from an extended network of data providers distributed globally. The interoperability of the heterogeneous data collections is achieved with the adoption and adaption of the ESPAS data model which is built entirely on ISO 19100 series geographic information standards. The ESPAS data portal manages a vocabulary of space physics keywords that can be used to narrow down data searches to observations of specific physical content. Such content-targeted search is an ESPAS innovation provided in addition to the commonly practiced data selection by time, location, and instrument. The article presents an overview of the architectural design of the ESPAS system, of its data model and ontology, and of interoperable services that allow the discovery, access and download of registered data. Emphasis is given to the standardization, and expandability concepts which represent also the main elements that support the building of long-term sustainability activities of the ESPAS e-infrastructure.
    Description: Published
    Description: 1177–1200
    Description: 1A. Geomagnetismo e Paleomagnetismo
    Description: 2A. Fisica dell'alta atmosfera
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 4
    Publication Date: 2021-07-21
    Description: The delayed ionospheric response is analyzed for two well‐defined 27‐day solar rotation periods in the year 2019 with solar radio flux index F10.7 and Global‐scale Observations of the Limb and Disk (GOLD) data, like solar extreme ultraviolet (EUV) flux proxy, O/N2 column density ratio and peak electron density, as well as International Global Navigation Satellite System Service rapid high‐rate total electron content (TEC) map data. Although the correlation between GOLD solar EUV flux proxy and TEC is similar to the correlation between F10.7 and TEC, it is shown that the estimated delays based on GOLD data are in much better agreement with recent studies using EUV measurements compared to the delays based on F10.7 data. The GOLD peak electron density correlates well with TEC and allows insight to a local time interval when the ionosphere is not controlled by solar activity changes (17:00 LT to 21:00 LT). The present study investigates the impact of the solar activity (F10.7, GOLD EUV flux proxy) and O/N2 column density ratio on the ionospheric delay for two representative solar rotation periods. The capabilities of GOLD data for future research on the ionospheric response to the 27‐day solar rotation period are demonstrated and discussed. These results are crucial information for precise ionospheric models and forecasts.
    Description: Key Points: The good correlation of Global‐scale Observations of the Limb and Disk (GOLD) extreme ultraviolet (EUV) proxy and GOLD peak electron density with total electron content (TEC) allows detailed studies of the delayed ionospheric response. The ionospheric delay to the 27‐day solar rotation period based on GOLD EUV proxy and TEC confirms recent delay estimates of about 1 day. GOLD measurements at different times of the day allow insight into ionization, recombination and related accumulation processes.
    Keywords: 538.767 ; ionosphere ; solar proxies ; time delay ; total electron content
    Type: article
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  • 5
    Publication Date: 2021-11-29
    Description: This paper presents a review on the PECASUS service, which provides advisories on enhanced space weather activity for civil aviation. The advisories are tailored according to the Standards and Recommended Practices of the International Civil Aviation Organization (ICAO). Advisories are disseminated in three impact areas: radiation levels at flight altitudes, GNSS-based navigation and positioning, and HF communication. The review, which is based on the experiences of the authors from two years of running pilot ICAO services, describes empiricalmodels behind PECASUS products and lists groundand space-based sensors, providing inputs for themodels and 24/7manualmonitoring activities. As a concrete example of PECASUS performance, its products for a post-stormionospheric F2-layer depression event are analyzed in more detail. As PECASUS models are particularly tailored to describe F2-layer thinning, they reproduce observationsmore accurately than the International Reference Ionospheremodel (IRI(STORM)), but, on the other hand, it is recognized that the service performance ismuch affected by the coverage of its input data. Therefore, more efforts will be directed toward systematic measuring of the availability, timeliness and quality of the data provision in the next steps of the service development.
    Description: Published
    Description: 3685
    Description: 2A. Fisica dell'alta atmosfera
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 6
    Publication Date: 2024-02-07
    Description: It is well known that space weather can cause significant disruptions to modern communications and navigation systems, leading to increased safety risks, economic losses, and reduced quality of life. Operators of critical infrastructures (both national and international) are also increasingly aware that extreme space-weather events can have severe impacts on their systems. For example, strong ionospheric disturbances can degrade, and sometimes deny access to satellite positioning, navigation, and timing services, central to the operation of many infrastructures. The mitigation of the effects of space weather on technical systems on the ground and in space, and the development of possible protective measures, are therefore of essential importance. We discuss how space weather drives a wide variety of ionospheric phenomena that can disrupt communications and navigation systems and how scientific understanding can help us to mitigate those effects. We also provide recommendations on further research and collaboration with industrial and governmental partners, which are essential for the development and operation of space weather services.
    Description: In press
    Description: OSA3: Climatologia e meteorologia spaziale
    Description: JCR Journal
    Keywords: Radio communication ; navigation ; satellite positioning ; broadcast ; ionosphere ; radio propagation ; 01.02. Ionosphere
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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