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  • 1
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    Reconstructed ozone concentration in Antarctica based on the relative abundance of freshwater diatoms providing from a sediment core of Profound Lake/King George Island/Antarctica (2021)
    PANGAEA
    Details
    Publication Date: 2023-07-18
    Description: Profound Lake (formerly known as Lago Glubokoe or Glubokoye) (62°11,066'S;058°54,413'W), is situated on Fildes Peninsula, the largest ice-free area (29 km2) of King George Island, the largest of the South Shetland Islands, located in the extreme southwestern part of the island. This lake lies 500 m from the base of the Collins glacier, close to the Uruguayan research base (Artigas) and Maxwell Bay. Morphologically it has a surface area of 90 km² and 14.7 m maximum depth. It's a holocenic, non-impacted, pro-glacial lake where diatoms are abundant and diverse. This organisms present a cell envelope, external to the plasma membrane, composed of rigid structure impregnated with silica called frustules, resistant to dissolution, that allow their preservation in sediment layers in the long term. These characteristics enable the use of diatoms in paleoenvironmental, paleoclimatic and paleoecological studies, thus we use the relative abundance of this organisms in a sediment corer in order to calibrate and evaluate the use of them as a proxy to reconstructed Ozone variability iin Antarctica.
    Keywords: Achnanthidium cf. maritimo-antarcticum; Age; AGE; Antarctica; Aulacoseira glubokoyensis; Brachysira minor; Depth, bottom/max; DEPTH, sediment/rock; Depth, top/min; Diatomella balfouriana; diatomos; Eunotia ralitsae; Fragilaria cf. capuccina; Gomphonema maritimo-antarcticum; Gomphonema sp.; Humidophila sp.; Humidophila tabellariaeformis; King George Island, Antarctica; Melosira cf. varians; Nitzschia cf. kleinteichiana; Ozon, reconstructed; ozone; Pinnularia borealis; Pinnularia cf. australomicrostauron; Pinnularia sp.; Planothidium australe; Planothidium rostrolanceolatum; Profound_Lake; proglacial lake; Psammothidium abundans; reconstructed model; SEDCO; Sediment corer; Stauroneis cf. delicata
    Type: Dataset
    Format: text/tab-separated-values, 506 data points
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    DATA PANGAEA
  • 2
    Electronic Resource
    Electronic Resource
    A high-energy solar flare burst complex and the physical properties of its source region (1987)
    Springer
    Solar physics 110 (1987), S. 317-326 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We discuss a solar flare microwave burst complex, which included a major structure consisting of some 13 spikes of 60 ms FWHM each, observed 21 May, 1984 at 90 GHz (3 mm). It was associated with a simultaneous very hard X-ray burst complex. We suggest that the individual spikes of both bursts were caused by the same electron population: the X-bursts by their bremsstrahlung, and the microwave bursts by their gyrosynchrotron emission. This latter conclusion is based on the evidence that the radio turnover frequency was ≤ 150 GHz. It follows that the emission sources were characterized by an electron density of about 1011 cm−3, a temperature of 5 × 108 K and a magnetic field of about 1400–2000 G. They had a size of about 350 km; if the energy release is caused by reconnection the sources of primary instability could have been smaller and in the form of thin sheets with reconnection speed at a fraction of the Alfvén velocity and burst-like energy injections of ≈ 1027 erg during about 50 ms each. The energized plasma knots lost their injection energy by saturated convective flux (collisionless conduction) in about 30 ms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00206427
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    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Interpretation of fast ripple structure in solar impulsive bursts (1985)
    Springer
    Solar physics 97 (1985), S. 363-373 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The hypothesis that solar impulsive bursts are comprised of quasi-quantised ultrarapid pulses convoluted with a variable pulse repetition rate R(t) is investigated by comparison of typical observations with numerical simulations. It is found that: (a) The ripple amplitude at burst peak increases rapidly with increase in the ratio Δ/T of pulse separation to pulse width. Consequently pulse widths T are generally much larger than the observed period Δt of small amplitude ripples. (b) In order to give a ripple amplitude of at least a few percent at burst peak together with reasonable burst rise and fall times without unreasonable ripple amplitude during rise and fall, the individual pulse shape must be sharply peaked but have substantial wings while the repetition rate R(t) must fall gradually away from its peak value but cut off rapidly in its wings. As a specific example, we present a simulation of the fast ripple structures observed in the impulsive 22 GHz burst of December 18, 1980. The relevance of these conclusions to physical modelling is briefly discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00165995
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    Paper (German National Licenses)
    Fulltext
  • 4
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    GPS Scintillations and Total Electron Content Climatology in the Southern American Sector (2020)
    intechopen
    Details
    Publication Date: 2020-03-17
    Description: The radio communication and navigation systems can be strongly affected by the ionospheric conditions, which are controlled by solar phenomena associated with radiation variations and solar wind disturbances. These phenomena can generate ionospheric large-scale plasma redistribution and irregularities with scale sizes varying from centimeters to hundred kilometers. These ionospheric irregularities can produce rapid fluctuations in the amplitude and phase of global navigation satellite system (GNSS) signals, degrading the accuracy of GNSS measurements. Here we give a short review of the ionospheric variations associated with solar phenomena, and the actual state of art in the investigations of long-term (seasonal and solar cycle scales) TEC variations and climatology of scintillations, with focus on the southern American sector. It also presented a new TEC calibration procedure when applied to single-frequency PPP.
    Description: Published
    Description: 2A. Fisica dell'alta atmosfera
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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    PAPER (OA)
  • 5
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    Ionospheric F-region response to the 26 September 2011 geomagnetic storm in the Antarctica American and Australian sectors (2018)
    Details
    Publication Date: 2022-06-15
    Description: The ionospheric response at middle and high latitudes in the Antarctica American and Australian sectors to the 26–27 September 2011 moderately intense geomagnetic storm was investigated using instruments including an ionosonde, riometer, and GNSS receivers. The multiinstrument observations permitted us to characterize the ionospheric storm-enhanced density (SED) and tongues of ionization (TOIs) as a function of storm time and location, considering the effect of prompt penetration electric fields (PPEFs). During the main phase of the geomagnetic storm, dayside SEDs were observed at middle latitudes, and in the nightside only density depletions were observed from middle to high latitudes. Both the increase and decrease in ionospheric density at middle latitudes can be attributed to a combination of processes, including the PPEF effect just after the storm onset, dominated by disturbance dynamo processes during the evolution of the main phase. Two SEDs–TOIs were identified in the Southern Hemisphere, but only the first episode had a counterpart in the Northern Hemisphere. This difference can be explained by the interhemispheric asymmetry caused by the high-latitude coupling between solar wind and the magnetosphere, which drives the dawn-to-dusk component of the interplanetary magnetic field. The formation of polar TOI is a function of the SED plume location that might be near the dayside cusp from which it can enter the polar cap, which was the case in the Southern Hemisphere. Strong GNSS scintillations were observed at stations collocated with SED plumes at middle latitudes and cusp on the dayside and at polar cap TOIs on the nightside.
    Description: Published
    Description: 1113–1129
    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
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    Review of Environmental Monitoring by Means of Radio Waves in the Polar Regions: From Atmosphere to Geospace (2022)
    Springer
    Details
    Publication Date: 2022-10-24
    Description: The Antarctic and Arctic regions are Earth’s open windows to outer space. They provide unique opportunities for investigating the troposphere–thermosphere–ionosphere–plasmasphere system at high latitudes, which is not as well understood as the mid- and low-latitude regions mainly due to the paucity of experimental observations. In addition, different neutral and ionised atmospheric layers at high latitudes are much more variable compared to lower latitudes, and their variability is due to mechanisms not yet fully understood. Fortunately, in this new millennium the observing infrastructure in Antarctica and the Arctic has been growing, thus providing scientists with new opportunities to advance our knowledge on the polar atmosphere and geospace. This review shows that it is of paramount importance to perform integrated, multi-disciplinary research, making use of long-term multi-instrument observations combined with ad hoc measurement campaigns to improve our capability of investigating atmospheric dynamics in the polar regions from the troposphere up to the plasmasphere, as well as the coupling between atmospheric layers. Starting from the state of the art of understanding the polar atmosphere, our survey outlines the roadmap for enhancing scientific investigation of its physical mechanisms and dynamics through the full exploitation of the available infrastructures for radio-based environmental monitoring.
    Description: Published
    Description: 1609–1698
    Description: 2A. Fisica dell'alta atmosfera
    Description: 5A. Ricerche polari e paleoclima
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 7
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    Climatology of ionospheric amplitude scintillation on GNSS signals at south American sector during solar cycle 24 (2022)
    Elsevier
    Details
    Publication Date: 2022-10-24
    Description: Scintillations are caused by ionospheric irregularities and can affect the propagation of trans-ionospheric radio signals. One way to understand and predict the impact of such irregularities on Global Navigation Satellite System (GNSS) signals is through the spatial/temporal characterization of the scintillation’s climatology during different phases of a solar cycle covering different latitudes and longitudes. This characterization is performed using amplitude scintillation index S4, during the full solar cycle 24, in the South American (SA) sector. The investigation considers the diurnal, daily, and seasonal variation of S4 index for climatological purpose, and the goal of this study is to investigate the scintillations covering a large spatial scale during the full solar cycle 24. The characterization shows a latitudinal asymmetry, whereas at the south, the scintillations were more frequent and their peak was more distant from the magnetic equator, which can be attributed by the South Atlantic Magnetic Anomaly (SAMA), and/or by the transequatorial meridional neutral winds. It also shows a longitudinal asymmetry, where the scintillations at the eastern sector occurred between November and February, while at the western sector, they occurred during the months of October, November, February and March, which can be attributed to the difference between the magnetic and geographic equators. The occurrence of scintillations during two distinct geomagnetic storms with similar storm time in the SA sector is also presented.
    Description: Published
    Description: 105872
    Description: 2A. Fisica dell'alta atmosfera
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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