69 research outputs found
Inter-Calibration and Statistical Validation of Topside Ionosphere Electron Density Observations Made by CSES-01 Mission
No full textThe China Seismo-Electromagnetic Satellite (CSES-01) provides in situ electron density (Ne) observations through Langmuir probes (LPs) in the topside ionosphere since February 2018. CSES-01 is a sun-synchronous satellite probing the ionosphere around two fixed local times (LTs), 14 LT in the daytime sector and 02 LT in the night-time sector, at an altitude of about 500 km. Previous studies evidenced that CSES-01 seems to underestimate Ne measurements with respect to those acquired by similar satellites or obtained from different instruments. To overcome this issue, we calibrated CSES-01 LP Ne observations through Swarm B satellite data, which flies approximately at CSES-01 altitude. As a first step, Swarm B LP Ne observations were calibrated through Faceplate (FP) Ne observations from the same satellite. Such calibration allowed solving the Ne overestimation made by Swarm LP during nighttime for low solar activity. Then, the calibrated Swarm B LP Ne observations were used to calibrate CSES-01 Ne observations on a statistical basis. Finally, the goodness of the proposed calibration procedure was statistically assessed through a comparison with Ne observations by incoherent scatter radars (ISRs) located at Jicamarca, Arecibo, and Millstone Hill. The proposed calibration procedure allowed solving the CSES-01 Ne underestimation issue for both daytime and nighttime sectors and brought CSES-01 Ne observations in agreement with corresponding ones measured by Swarm B, ISRs, and with those modelled by the International Reference Ionosphere (IRI). This is a first fundamental step towards a possible future inclusion of CSES-01 Ne observations in the dataset underlying IRI for the purpose of improving the description of the topside ionosphere made by IRI
Polar Cap Patches Scaling Properties: Insights from Swarm Data
No full textAmong the effects of space weather, the degradation of air traffic communications and satellite-based navigation systems are the most notable. For this reason, it is of uttermost importance to understand the nature and origin of ionospheric irregularities that are at the base of the observed communication outages. Here we focus on polar cap patches (PCPs) that constitute a special class of ionospheric irregularities observed at very high latitudes in the F region. To this purpose we use the so-called PCP flag, a Swarm Level 2 product, that allows for identifying PCPs. We relate the presence of PCPs to the values of the first- and second-order scaling exponents and intermittency estimated from Swarm A electron density fluctuations and to the values of the Rate Of change of electron Density Index (RODI) for two different levels of geomagnetic activity, over a time span of approximately 3.5 years starting on 16 July 2014. Our findings show that values of RODI, first- and second-order scaling exponents and intermittency corresponding to measurements taken inside PCPs differ from those corresponding to measurements taken outside PCPs. Additionally, the values of the first- and second-order scaling exponents and of intermittency indicate that PCPs are in a turbulent state. Investigation of the coincidence of loss of lock (LoL) events with PCPs displayed that approximately 57.4% of LoLs in the Northern hemisphere and 45.7% in the Southern hemisphere occur in coincidence of PCPs when disturbed geomagnetic activity is considered. During quiet geomagnetic conditions these percentages decrease to 51.4% in the Northern hemisphere and to 20.1% in the Southern hemisphere
The 8 June 2000 ULF wave activity: A case study
No full textWe examine the characteristics of a train of ULF waves observed in the magnetosphere
and at ground after the sudden impulse (SI) onset of 8 June 2000. A highly monochromatic
and large-amplitude wave at f=3.3 mHz was observed between 9:10 and 9:50 UT at
the GOES8 orbit (on the dawn flank of the magnetosphere) and across a wide longitudinal
range of ground stations from low to high latitudes. The combination of the long period of
these pulsations (5 min), their extended duration (40 min), the latitude-independent
frequency, and the small azimuthal wave number suggests the occurrence of a global
magnetospheric mode driven by the sudden enhancements of the solar wind dynamic
pressure. The amplitude and cross-phase analysis of the wave activity on the ground and
the polarization pattern indicate that the global mode coupled to the field line resonance
(FLR) occurs at different latitudes at different local times. Such FLRs occurred at latitudes
smaller than usually observed at the same frequency, suggesting a significant reduction of
the local field line eigenfrequencies as compared with usual values. A model estimation
(time of flight approximation) of such eigenfrequencies suggests a change in the
magnetospheric field geometry characterized by more elongated field lines than those
for usual conditions. It was probably caused by the compression of the magnetosphere
driven by the pressure pulse coupled with the stable northward orientation of the
interplanetary magnetic field.PublishedA022041A. Geomagnetismo e PaleomagnetismoJCR Journa
Comparison between IRI and preliminary Swarm Langmuir probe measurements during the St. Patrick storm period
No full textPreliminary Swarm Langmuir probe measurements recorded during March 2015, a period of time including the St.
Patrick storm, are considered. Specifically, six time periods are identified: two quiet periods before the onset of the
storm, two periods including the main phase of the storm, and two periods during the recovery phase of the storm.
Swarm electron density values are then compared with the corresponding output given by the International Reference
Ionosphere (IRI) model, according to its three different options for modelling the topside ionosphere. Since the
Swarm electron density measurements are still undergoing a thorough validation, a comparison with IRI in terms of
absolute values would have not been appropriate. Hence, the similarity of trends embedded in the Swarm and IRI
time series is investigated in terms of Pearson correlation coefficient. The analysis shows that the electron density
representations made by Swarm and IRI are different for both quiet and disturbed periods, independently of the chosen
topside model option. Main differences between trends modelled by IRI and those observed by Swarm emerge,
especially at equatorial latitudes, and at northern high latitudes, during the main and recovery phases of the storm.
Moreover, very low values of electron density, even lower than 2 × 10^4 cm−3, were simultaneously recorded in the
evening sector by Swarm satellites at equatorial latitudes during quiet periods, and at magnetic latitudes of about
±60° during disturbed periods. The obtained results are an example of the capability of Swarm data to generate an
additional valuable dataset to properly model the topside ionosphere
REPRESENTATION OF THE PICTURE “CHRIST’S CRUCIFIXION” BY JURAJ JULIJE KLOVIĆ
No full textAutor je u tekstu prikazao minijaturu Jurja Julija Klovića “Kristovo raspeće” iz privatne zbirke Luciana Salvia iz Parme. U bilješkama se veže na ikonografske i teološke konotacije djela majstora Mikelanđelovog kruga iz sredine šesnaestog stoljeća, te ukratko navodi dvojbe u pogledu atribucija pojedinih studija i slika koje povezuje sa spomenutom minijaturom. Tekstu je pridodano devet reprodukcija slika koje su zbog tehnike fotokopiranja izgubile dosta od svoje vjerodostojnosti. Rad preveo s talijanskog Slavko Matejčić.The author describes the illumination “Christ’s Crucifixion” by J. J. Klović, possession Luciano Salvi from Parma. He mentiones the iconographical and theological conotations found in works of some artists from the Michelangelo circle from the mid 16. century and enumerates doubts regarding attributions of some studies and works connected to the mentioned illumination. This book includes nine reproductions of works. Unfortunatelly, these reproductions lost much of their attendibility because of the technology of copying used. Translated from Italian by Slavko Matejčić
Efficacy of Nonpreserved Sodium Hyaluronate Artificial Tears in Dry Eye Disease Patients Treated with Prostaglandin Analogs for Primary Open-Angle Glaucoma: A Prospective, Nonrandomized, Open-Label Pilot Study
No full textPURPOSE: Dry eye disease (DED) can be triggered using preserved ophthalmic formulations or prostaglandin analogs. In this prospective, nonrandomized, open-label pilot study, we evaluated the efficacy of a 0.15% hyaluronic acid (HA) nonpreserved ophthalmic formulation in decreasing DED symptoms in patients with open-angle glaucoma treated with prostaglandin analogs. METHODS: 30 patients with DED receiving chronic treatment with prostaglandin analogs for primary open-angle glaucoma or ocular hypertension were administered ophthalmic formulations 3 times daily for 12 weeks. Foreign body sensation, burning, stinging, dryness, pain, frequency of symptoms, Ocular Surface Disease Index (OSDI), conjunctival hyperaemia, corneal fluorescein staining (CFS), tear film break-up time (TBUT), best-corrected visual acuity, Schirmer test results, and 25-item National Eye Institute Visual Function Questionnaire score between the baseline and 4 and 12 weeks were evaluated. RESULTS: The analysis shows that all primary endpoints improved; in particular, burning sensation and the frequency of symptoms after 4 and 12 weeks of treatment (p 90% of cases at 12 weeks of treatment. CONCLUSION: The present study shows that the ophthalmic formulation containing 0.15% HA has a promising beneficial effect on reducing the signs and symptoms of DED in patients treated with prostaglandin analogs
Mid- and High-Latitude Electron Temperature Dependence on Solar Activity in the Topside Ionosphere through the Swarm B Satellite Observations and the International Reference Ionosphere Model
No full textThis study focuses on the open question of the electron temperature (Te) variation with solar activity in the topside ionosphere at mid- and high latitudes. It takes advantage of in situ observations taken over a decade (2014–2023) from Langmuir probes on board the low-Earth-orbit Swarm B satellite and spanning an altitude range of 500–530 km. The study also includes a comparison with Te values modeled using the International Reference Ionosphere (IRI) model and with Millstone Hill (42.6° N. 71.5° W) incoherent scatter radar observations. The largest Te variation with solar activity was found at high latitudes in the winter season, where Te shows a marked decreasing trend with solar activity in the polar cusp and auroral regions and, more importantly, at sub-auroral latitudes in the nightside sector. Differently, in the summer season, Te increases with solar activity in the polar cusp and auroral regions, while for equinoxes, variations are smaller and less clear. Mid-latitudes generally show negligible Te variations with solar activity, which are mostly within the natural dispersion of Te observations. The comparison between measured and modeled values highlighted that future implementations of the IRI model would benefit from an improved description of the Te dependence on solar activity, especially at high latitudes
Entry into the Paradise of \u2749 and Biblical Revelation
No full textThis article explores some texts in which Chiara Lubich speaks about the beginning of her mystical experience during the summer of 1949 that is known as “Paradise ’49.” This exploration seeks to understand these texts in the light of biblical revelation, in particular Pauline and Johannine theology. The author focuses on two aspects. The first of these concerns the role of living the Word of God leading up to this experience. The second concentrates on what Chiara wrote about the special circumstances in which the mystical experience began after a “Pact” made with Igino Giordani, a noted Catholic writer and politician
Latitudinal dependence of geomagnetically induced currents during geomagnetic storms
No full textMajor geomagnetic storms drive rapid intensification and variability of magnetospheric and iono- spheric current systems that give rise to large ground-induced currents (GIC). Space weather as- sociated GIC pose a serious threat to the reliability of power-transmission systems and other elec- trically conducting infrastructure such as oil and gas pipelines. The most severe effects are ob- served at high latitudes due to ionospheric currents associated with the aurora. However, as power transmission grid and pipeline infrastructure continues to grow at middle and low-latitudes, GIC hazards are no longer just concerns of high-latitude regions. We investigate how GIC amplitude varies in latitude during six major geomagnetic storms that occurred between 1989 and 2004. Due to limited direct GIC measurements, a proxy of the geoelectric field is used, i.e. the GIC index. This is calculated for the selected geomagnetic storms using 25 magnetic observatories relatively uniformly distributed in geomagnetic latitude, 14 magnetic observatories with longitudes varying within a range of 45 degrees as well as for the 7 November 2004 storm using 104 observatories. In addition, we suggest a possible way to follow the latitudinal displacement of the auroral oval dur- ing geomagnetic storms through the maximum value of GIC index, estimated over 2-hour inter- vals on a wide number of magnetic observatories
Modeling the Topside Ionosphere Effective Scale Height through In Situ Electron Density Observations by Low-Earth-Orbit Satellites
No full textIn this work, we aim to characterize the effective scale height at the ionosphere F2-layer peak (H0) by using in situ electron density (Ne) observations by Langmuir Probes (LPs) onboard the China Seismo-Electromagnetic Satellite (CSES—01). CSES—01 is a sun-synchronous satellite orbiting at an altitude of ~500 km, with descending and ascending nodes at ~14:00 local time (LT) and ~02:00 LT, respectively. Calibrated CSES—01 LPs Ne observations for the years 2019–2021 provide information in the topside ionosphere, whereas the International Reference Ionosphere model (IRI) provides Ne values at the F2-layer peak altitude for the same time and geographical coordinates as CSES—01. CSES—01 and IRI Ne datasets are used as anchor points to infer H0 by assuming a linear scale height in the topside representation given by the NeQuick model. COSMIC/FORMOSAT—3 (COSMIC—1) radio occultation (RO) data are used to constrain the vertical gradient of the effective scale height in the topside ionosphere in the linear approximation. With the CSES—01 dataset, we studied the global behavior of H0 for daytime (~14:00 LT) and nighttime (~02:00 LT) conditions, different seasons, and low solar activity. Results from CSES—01 observations are compared with those obtained through Swarm B satellite Ne-calibrated measurements and validated against those from COSMIC—1 RO for similar diurnal, seasonal, and solar activity conditions. H0 values modeled by using CSES—01 and Swarm B-calibrated observations during daytime both agree with corresponding values obtained directly from COSMIC—1 RO profiles. Differently, H0 modeling for nighttime conditions deserves further investigation because values obtained from both CSES—01 and Swarm B-calibrated observations show remarkable and spatially localized differences compared to those obtained through COSMIC—1. Most of the H0 mismodeling for nighttime conditions can probably to be attributed to a sub-optimal spatial representation of the F2-layer peak density made by the underlying IRI model. For comparison, H0 values obtained with non-calibrated CSES—01 and Swarm B Ne observations are also calculated and discussed. The methodology developed in this study for the topside effective scale height modeling turns out to be applicable not only to CSES—01 satellite data but to any in situ Ne observation by low-Earth-orbit satellites orbiting in the topside ionosphere
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