B2 Thickness Parameter Response to Equinoctial Geomagnetic Storms

The thickness parameters that most empirical models use are generally defined by empirical relations related to ionogram characteristics. This is the case with the NeQuick model that uses an inflection point below the F2 layer peak to define a thickness parameter of the F2 bottomside of the electron density profile, which is named B2. This study is focused on the effects of geomagnetic storms on the thickness parameter B2. We selected three equinoctial storms, namely 17 March 2013, 2 October 2013 and 17 March 2015. To investigate the behavior of the B2 parameter before, during and after those events, we have analyzed variations of GNSS derived vertical TEC (VTEC) and maximum electron density (NmF2) obtained from manually scaled ionograms over 20 stations at middle and low latitudes of Asian, Euro-African and American longitude sectors. The results show two main kinds of responses after the onset of the geomagnetic events: a peak of B2 parameter prior to the increase in VTEC and NmF2 (in ~60% of the cases) and a fluctuation in B2 associated with a decrease in VTEC and NmF2 (~25% of the cases). The behavior observed has been related to the dominant factor acting after the CME shocks associated with positive and negative storm effects. Investigation into the time delay of the different measurements according to location showed that B2 reacts before NmF2 and VTEC after the onset of the storms in all the cases. The sensitivity shown by B2 during the studied storms might indicate that experimentally derived thickness parameter B2 could be incorporated into the empirical models such as NeQuick in order to adapt them to storm situations that represent extreme cases of ionospheric weather-like conditions.

Observations of precipitation energies during different types of pulsating aurora

Pulsating aurora (PsA) is a diffuse type of aurora with different structures switching on and off with a period of a few seconds. It is often associated with energetic electron precipitation (>10 keV) resulting in the interaction between magnetospheric electrons and electromagnetic waves in the magnetosphere. Recent studies categorize pulsating aurora into three different types – amorphous pulsating aurora (APA), patchy pulsating aurora (PPA), and patchy aurora (PA) – based on the spatial extent of pulsations and structural stability. Differences in precipitation energies of electrons associated with these types of pulsating aurora have been suggested. In this study, we further examine these three types of pulsating aurora using electron density measurements from the European Incoherent Scatter (EISCAT) VHF/UHF radar experiments and Kilpisjärvi Atmospheric Imaging Receiver Array (KAIRA) cosmic noise absorption (CNA) measurements. Based on ground-based all-sky camera images over the Fennoscandian region, we identified a total of 92 PsA events in the years between 2010 and 2020 with simultaneous EISCAT experiments. Among these events, 39, 35, and 18 were APA, PPA, and PA types with a collective duration of 58, 43, and 21 h, respectively. We found that, below 100 km, electron density enhancements during PPAs and PAs are significantly higher than during APA. However, there are no appreciable electron density differences between PPA and APA above 100 km, while PA showed weaker ionization. The altitude of the maximum electron density also showed considerable differences among the three types, centered around 110, 105, and 105 km for APA, PPA, and PA, respectively. The KAIRA CNA values also showed higher values on average during PPA (0.33 dB) compared to PA (0.23 dB) and especially APA (0.17 dB). In general, this suggests that the precipitating electrons responsible for APA have a lower energy range compared to PPA and PA types. Among the three categories, the magnitude of the maximum electron density shows higher values at lower altitudes and in the late magnetic local time (MLT) sector (after 5 MLT) during PPA than during PA or APA. We also found significant ionization down to 70 km during PPA and PA, which corresponds to ∼200 keV of precipitating electrons.

Observations of precipitation energies during different types of pulsating aurora

Pulsating aurora (PsA) is a diffuse type of aurora with different structures switching on and off with a period of few seconds. It is often associated with energetic electron precipitation (10 keV) resulted in the interaction between magnetospheric electrons and electromagnetic waves in the magnetosphere. Recent studies categorize pulsating aurora into three different types: amorphous pulsating aurora (APA), patchy pulsating aurora (PPA), and patchy aurora (PA) based on the spatial extent of pulsations and structural stability. Differences in precipitation energies of electrons associated with these types of pulsating aurora have been suggested. In this study, we further examine these three types of pulsating aurora using electron density measurements from the European Incoherent Scatter (EISCAT) VHF/UHF radar experiments and Kilpisjärvi Atmospheric Imaging Receiver Array (KAIRA) cosmic noise absorption (CNA) measurements. Based on ground-based all-sky camera images over the Fennoscandian region, we identified a total of 92 PsA events in the years between 2010 and 2020 with simultaneous EISCAT experiments. Among these events, 39, 35, and 18 were APA, PPA, and PA types with a collective duration of 58 hrs, 43 hrs, and 21 hrs, respectively. We found that below 100 km, electron density enhancements during PPAs and PAs are significantly higher than during APA. However, there are no appreciable electron density differences between PPA and APA above 100 km, while PA showed weaker ionization. The altitude of the maximum electron density also showed considerable differences among the three types, centered around 110 km, 105 km, and 105 km for APA, PPA, and PA, respectively. The KAIRA CNA values also showed higher values on average during PPA (0.33 dB) compared to PA (0.23 dB) and especially APA (0.17 dB). In general, this suggests that the precipitating electrons responsible for APA have a lower energy range compared to PPA and PA types. Among the three categories, the magnitude of the maximum electron density shows higher values during PPA at lower altitudes and in the late MLT sector (after 5 MLT). We also found significant ionization down to 70 km during PPA and PA, which corresponds to ~ 200 keV energies of precipitating pulsating aurora electrons.

Gas Sensing of (SnO2)1-x(ZnO)x Composite Associating with Electrical Properties

Semiconductor-based gas sensors were prepared, that use n-type tin oxide (SnO2) and tin oxide: zinc oxide composite (SnO2)1-x(ZnO)x at different x ratios using pulse laser deposition at room temperature. The prepared thin films were examined to reach the optimum conditions for gas sensing applications, namely X-ray diffraction, Hall effect measurements, and direct current conductivity. It was found that the optimum crystallinity and maximum electron density, corresponding to the minimum charge carrier mobility, appeared at 10% ZnO ratio. This ratio appeared has the optimum NO2 gas sensitivity for 5% gas concentration at 300 °C working temperature.

RESPONSE OF F2- REGION MAXIMUM ELECTRON DENSITY (NmF2/foF2) TO SOLAR ACTIVITY USING PEARSON PRODUCT MOMENT CORRELATION

Introduction: The ionosphere owes its origin primarily to ultraviolet radiation from the Sun. The ionosphere is an essential part of the Earth’s upper atmosphere. It is ionized by solar radiation and influences transionospheric radio wave propagation. Maximum electron density of the F2- layer (NmF2) is an important parameter for studying the ionosphere. The ionospheric F2-region maximum electron density (NmF2) depends strongly on solar activity, it also suffers temporal and spatial variations. Aim: The aim of this paper is to investigate the response of NmF2 to solar activity during high solar activity (HSA), moderate solar activity (MSA) and low solar activity (LSA) years using correlation analysis. Materials and Methods: The data used in this work are the hourly NmF2 values derived from foF2 data observed at Jicamarca (Lat.11.9 oS, Long.76.8 oW) and Puerto Rico (Lat.18.5 oN, Long.67.2 oW) during high solar activity HSA (2002), moderate solar activity MSA (2011) and low solar activity LSA (2006) years. The NmF2 data were evaluated using the relation in equation 1 NmF2 = 1.24 x 1010 (foF2)2 (1) Where NmF2 is in el/m3 and foF2 is in MHz. Pearson Product Moment Correlation (PPMC) was used to further analyse the NmF2 data. Results: Our results revealed two unequal NmF2 peaks. The NmF2 peaks values at Jicamarca (60 - 240; 63– 204) x 1010 el/m3 are observed to be higher in values than those at Puerto Rico (63 – 187; 57 – 164) x 1010 el/m3. The highest NmF2 peak values of 240 and 187x 1010 el/m3 occurred during March equinox at 09:00 and 14:00 hours at Jicamarca and Puerto Rico respectively during HSA year. Conclusion: Correlation analysis for the three epochs of solar activity revealed that NmF2 showed positive correlation with sunspot number with highest correlation values of 0.904 and 0.976 at Jicamarca and Puerto Rico stations respectively during MSA year.

The use of satellite beacon TEC data from GRBR campaign-based observations for ionosphere tomography over West Java Indonesia

The experiment of ionospheric tomographic reconstruction using satellite beacon TEC data from two or more adjacent GRBR observation stations following equatorial latitude and longitude have been conducted on campaign-based observation in Sumedang, Pameungpeuk and Indramayu West Java on 2016 and 2017. The reconstruction technique utilized is a simple algebraic reconstruction technique (ART). The result obtained is the ionosphere electron density distribution along the longitude of 108 degrees East over the area of West Java and Indonesia. The ionosphere electron density parameters obtained from the IRI-2012 Model were used as the initiation to construct ionospheric tomographic reconstruction. The validation performed by correlating foF2 from the ionospheric tomographic reconstruction with foF2 obtained from ionosonde observation at Sumedang station, one of the GRBR observation sites shows that corresponded to the correlation coefficient value of 0.8665, with a bias frequency of 1.386 MHz, whereas the correlation with the maximum electron density value obtained from the IRI-2016 model gives a correlation coefficient value of 0.8958. a bias frequency of 1.386 MHz, whereas the correlation with the maximum electron density value obtained from the IRI-2016 model gives a correlation coefficient value of 0.8958.

The State of the Solar Wind, Magnetosphere, and Ionosphere During the Maunder Minimum

Both direct observations and reconstructions from various datasets, suggest that conditions were radically different during the Maunder Minimum (MM) than during the space era. Using an MHD model, we develop a set of feasible solutions to infer the properties of the solar wind during this interval. Additionally, we use these results to drive a global magnetospheric model. Finally, using the 2008/2009 solar minimum as an upper limit for MM conditions, we use results from the International Reference Ionosphere (ILI) model to speculate on the state of the ionosphere. The results describe interplanetary, magnetospheric, and ionospheric conditions that were substantially different than today. For example: (1) the solar wind density and magnetic field strength were an order of magnitude lower; (2) the Earth’s magnetopause and shock standoff distances were a factor of two larger; and (3) the maximum electron density in the ionosphere was substantially lower.

Evolution of the small ball-like structures in the plasma focus discharge

The experiments were carried out in the PF-1000 plasma-focus device at the maximum current reaching about 2 MA, at the deuterium or neon filling and with deuterium injected from a gas-puff nozzle placed on the axis of the anode face. Ball-like structures of diameters of 1-12 mm were identified in interferometric and XUV pinhole camera frames. We made the statistical description of their parameters. A lifetime of the ball-like structures was in the range from 30 to 210 ns, and in some cases even more. These structures appeared mostly at the surface of the imploding plasma shell and they did not change their position in relation to the anode end. During the evolution of these structures, interferometric fringes were observed near the surfaces of the structures only, and their internal parts were initially chaotic (without noticeable) fringes. Subsequently the number of interferometric fringes increased (the internal ‘chaotic’ area was filled with fringes too) and later on it decreased. The radii of the ball-like structures were mostly increasing during their existence. The maximum electron density reached the value of 1024 to 1025 m-3. The ball-like structures decayed by absorption inside the expanded pinch column and/or gradually expired in rare plasma outside of the dense plasma column.

Correlation studies for B-spline modeled F2 Chapman parameters obtained from FORMOSAT-3/COSMIC data

The determination of ionospheric key quantities such as the maximum electron density of the F2 layer NmF2, the corresponding F2 peak height hmF2 and the F2 scale height HF2 are of high relevance in 4-D ionosphere modeling to provide information on the vertical structure of the electron density (Ne). The Ne distribution with respect to height can, for instance, be modeled by the commonly accepted F2 Chapman layer. An adequate and observation driven description of the vertical Ne variation can be obtained from electron density profiles (EDPs) derived by ionospheric radio occultation measurements between GPS and low Earth orbiter (LEO) satellites. For these purposes, the six FORMOSAT-3/COSMIC (F3/C) satellites provide an excellent opportunity to collect EDPs that cover most of the ionospheric region, in particular the F2 layer. For the contents of this paper, F3/C EDPs have been exploited to determine NmF2, hmF2 and HF2 within a regional modeling approach. As mathematical base functions, endpoint-interpolating polynomial B-splines are considered to model the key parameters with respect to longitude, latitude and time. The description of deterministic processes and the verification of this modeling approach have been published previously in Limberger et al. (2013), whereas this paper should be considered as an extension dealing with related correlation studies, a topic to which less attention has been paid in the literature. Relations between the B-spline series coefficients regarding specific key parameters as well as dependencies between the three F2 Chapman key parameters are in the main focus. Dependencies are interpreted from the post-derived correlation matrices as a result of (1) a simulated scenario without data gaps by taking dense, homogenously distributed profiles into account and (2) two real data scenarios on 1 July 2008 and 1 July 2012 including sparsely, inhomogeneously distributed F3/C EDPs. Moderate correlations between hmF2 and HF2 as well as inverse correlations between NmF2 and HF2 are reflected from the simulation. By means of the real data studies, it becomes obvious that the sparse measurement distribution leads to an increased weighting of the prior information and suppresses the parameter correlations which play an important role regarding the parameter estimability. The currently implemented stochastic model is in need of improvement and does not consider stochastic correlations which consequently cannot occur.