Vertical Drift Research Articles

Equinoctial asymmetry of plasma bubble occurrence and electric field at evening: GPS and ionosonde measurements in Southeast Asia

We have investigated equinoctial asymmetry of scintillation occurrence and zonal irregularity drift velocity observed with closely-spaced GPS receivers at Kototabang (0.20°S, 100.32°E; geomagnetic latitude 10.6°S), Indonesia during a period from 2003 to 2016, and found that the scintillation occurrence rate is higher in Mar. equinox than in Sep. equinox, and that the eastward drift velocity at post-sunset is higher in Mar. equinox than in Sep. equinox. This result is consistent with previous work done by Otsuka et al. (2006), who have analyzed scintillation and zonal drift velocity data obtained at Kototabang in 2003–2004, and suggests that the eastward drift velocity corresponding to the downward electric field at post-sunset may be related to the pre-reversal enhancement of eastward electric field, which could play an important role in generating plasma bubble. In this study, we have investigated vertical drift velocity by analyzing the ionosonde data obtained near magnetic equator (Chumphon, Bac Lieu, and Cebu) during a period from 2003 to 2016, and found that the upward drift velocity at post-sunset is larger in Mar. equinox than Sep. equinox. We also find that solar activity dependence of the zonal and vertical drift velocities is more clearly seen in Mar. equinox than in Sep. equinox. In order to consider the mechanism causing the equinoctial asymmetry of the drift velocities, foF2 obtained by the ionosondes is also analyzed. We find that foF2 also depends on solar activity more clearly in Mar. equinox than in Sep. equinox, and that foF2 during high solar activity conditions is higher in Mar. equinox than in Sep. equinox. These results suggest that in Mar. equinox, due to high electron density, intense electric field could be generated through the F-region dynamo so that plasma bubble likely occurs.

Signature of thunderstorm induced acoustic and gravity waves at low latitude Indian sector

This study reports thunderstorm-generated acoustic and gravity waves from a tropical location using newly launched Indian navigation system NavIC for the first time. The detection of acoustic wave components in travelling ionospheric disturbance (TID) measurement is very significant. In compared to acoustic wave gravity wave signature is more ubiquitous because gravity wave propagates in thermospheric altitude by dissipative filtering process. The turbulent nature in plasma characteristics due to strong vertical drift and plasma motion in lower latitude region generate strong scintillation effect and plasma bubble. Large temperature gradient at thermospheric altitude also provides a strong attenuation effect in this region for comparatively high frequency acoustic wave. We have found the TID signatures on TEC variation for acoustic wave up to 0.4 TECU for both the days whereas gravity wave induced signatures went up to 0.8 TECU. Measurements using GPS signal validate signatures obtained from the NavIC signal. The study shows the potential of application of NavIC system for middle atmosphere as well as thermospheric study and understanding of coupling process between various atmospheric layers in tropical region which is not well known so far.

Cross-Validation of the Ionospheric Vertical Drift Measurements Based on ICON/IVM, Swarm, and the Ground-Based Radar at the Jicamarca Radio Observatory

Cross-Validation of the Ionospheric Vertical Drift Measurements Based on ICON/IVM, Swarm, and the Ground-Based Radar at the Jicamarca Radio Observatory

Equatorial spread-F forecasting model with local factors using the long short-term memory network

The predictability of the nighttime equatorial spread-F (ESF) occurrences is essential to the ionospheric disturbance warning system. In this work, we propose ESF forecasting models using two deep learning techniques: artificial neural network (ANN) and long short-term memory (LSTM). The ANN and LSTM models are trained with the ionogram data from equinoctial months in 2008 to 2018 at Chumphon station (CPN), Thailand near the magnetic equator, where the ESF onset typically occurs, and they are tested with the ionogram data from 2019. These models are trained especially with new local input parameters such as vertical drift velocity of the F-layer height (Vd) and atmospheric gravity waves (AGW) collected at CPN station together with global parameters of solar and geomagnetic activity. We analyze the ESF forecasting models in terms of monthly probability, daily probability and occurrence, and diurnal predictions. The proposed LSTM model can achieve the 85.4% accuracy when the local parameters: Vd and AGW are utilized. The LSTM model outperforms the ANN, particularly in February, March, April, and October. The results show that the AGW parameter plays a significant role in improvements of the LSTM model during post-midnight. When compared to the IRI-2016 model, the proposed LSTM model can provide lower discrepancies from observational data.Graphical

Variability and distribution of nighttime equatorial to mid latitude ionospheric irregularities and vertical plasma drift observed by FORMOSAT-5 Advanced Ionospheric Probe in-situ measurements from 2017 – 2020

Irregularities in ionospheric plasma distribution can result in severe scintillation and disruption to the radio frequencies utilized for satellite communications and navigation. In the low and mid latitudes, these irregularities can include Equatorial Plasma Bubbles (EPBs) and Travelling Ionospheric Disturbances (TIDs). EPBs are irregularities manifesting in low latitude nighttime ionosphere plasma density that can extend along magnetic field lines with zonal scales on the order of 100 km or less, while TIDs are propagating wave disturbances. High frequency in-situ measurements of ionospheric plasma aboard spacecraft in Low Earth Orbit (LEO) are a direct measurement of irregularities in plasma density and are therefore valuable for resolving EPB and TID occurrences, variability, and relation to other ionospheric parameters that are believed to play a driving role in the formation of such irregularities. In this study, we utilize observations taken over a three-year period between 2017 and 2020 by the Advanced Ionospheric Probe (AIP) carried aboard the FORMOSAT-5 satellite to examine the spatial, seasonal, and interannual variability of equatorial to mid latitude ionospheric irregularities and vertical ion drift during this time. AIP provides in-situ measurements of ion density and vertical ion drift in the equatorial to mid latitude ionosphere at approximately 720 km altitude with local times between 22:00 – 23:00 local time. Our global scale results resolve distinct and inter-annually recurrent seasonal patterns in the distribution of nighttime ionospheric irregularities and vertical plasma drift during this time. Elevated occurrences of ion density irregularities are resolved along the Equatorial Ionization Anomaly (EIA) latitudes, while notable occurrences with variability consistent with EPBs also observed along the low and equatorial magnetic latitudes. Zonal variability of equatorial irregularities consistent with the signatures of nonmigrating atmospheric tides are observed. It is also notable that the occurrences and geographic distribution of ion density irregularities showed a considerable level of interannual variability, especially at mid latitudes over the South Atlantic and Southern African sectors, which showed much higher levels of irregularities in 2017–––2018, compared to 2019 and 2020. In comparison, the spatial and interannual variation of the co-located vertical ion drifts were much more consistent during the years examined, indicating that the driver for the observed interannual variability in ion density irregularities cannot be attributed to the vertical ion drift at the same time and location of the observations. This highlights the need for in-situ instruments distributed across multiple satellites in different local time zones.

Statistical Characteristics of the Occurrence of ERI and FRI in the Equatorial Ionosphere With Observations of JULIA Radar

AbstractBased on observations of the Jicamarca Unattended Long‐term investigations of the Ionosphere and Atmosphere (JULIA) radar, we perform statistical analysis on the occurrence of 3‐m‐scale E‐region irregularities and F‐region irregularities (FRI) in Jicamarca region of South America. The results show that there is a negative correlation between the occurrence rates of equatorial irregularities in E‐ and F‐region. When the equatorial spread F appears, the occurrence rate of irregularities in E‐layer decreases. By analyzing the ion zonal drift velocity detected by JULIA radar, it is proposed that the vertically polarized electric field in the bottom F‐layer could extend downward to E‐layer when FRI appears, leading to the weakening or even reversal of E‐layer electric field. As a result, the electron vertical drift velocity in the E‐layer decreases so as to suppress the growth rate of two‐stream instability, which cause a weakening or even disappearance of equatorial irregularities in E‐region.

Evaluation of the performance of F-layer peak height models used in IRI-2016 over the Indian equatorial and low latitudes

The performance of different height models (BSE-1979, AMTB-2013, and SHU-2015) in the International Reference Ionosphere (IRI-2016) is evaluated over the Indian equatorial and low latitude sectors. The impact of deviations in the modelled hmF2 on the estimation of electron density profiles and the Total Electron Content (TEC) is examined using the three different hmF2 methods in IRI-2016. For this study digisonde observations over Trivandrum (8.5 °N, 76.9 °E) and Ahmedabad (23.0 °N, 72.5 °E) along with GPS observations over Colombo (6.8 °N, 79.8 °E) and Ahmedabad during a high solar activity year 2014 are considered. A comparison of electron density profiles between digisonde and IRI-2016 at both the equatorial station, Trivandrum, and the low latitude station, Ahmedabad, revealed significant deviations with higher deviations in the post sunset hours at the equator. The three height methods have shown significant differences in their predictions of hmF2 at both locations. At the equator, the SHU-2015 method shows better estimates closer to the measurement values, than the other two methods except at Pre-Reversal Enhancement (PRE) time, during which, the AMTB-2013 method shows better performance. At the low latitude station, the newly added methods (SHU-2015 and AMTB-2013) do not indicate any improvements in estimating the hmF2. The availability of three different height methods in IRI-2016 is exploited to understand the modifications if any, in the ionospheric height structure and TEC for different hmF2 methods and the corresponding results are presented. As the variations in hmF2 are used to derive vertical drift on many occasions in the absence of incoherent scatter radar, this study is significant in assessing the relative efficacy of the three height models and hence useful to understand various ionospheric processes over the low/equatorial latitudes.

The Role of Neutral Wind Velocity and Its Vertical Component on Predictability of Formation and Localization of Sporadic E (Es)

The formation and localization of sporadic E (Es) layers predicted by the ion vertical drift velocity and its vertical change in the lower thermosphere during nighttime are shown analytically and by numerical simulations. The consideration of the existence of a minimum negative value of the vertical change of the ion vertical drift velocity as a necessary condition of formation of the Es layer and determining ion convergence rate into this layer is extended in case of the presence of vertical wind. Upward vertical wind can shift the convergence regions upward, while downward vertical wind shifts them downward, unlike the cases of the presence of only meridional and zonal winds. It also changes the ion convergence rate compared to the one with just a horizontal wind. It is shown for the first time that the upward constant wind also causes the convergence of ions with the maximum rate in the region where the ion-neutral collision frequency is equal to their cyclotron frequency. While demonstrating the presented theory by numerical simulations, HWM14 data is used for the meridional and zonal wind velocity profiles and the presence of its vertical component is assumed. In this case, in addition to the estimated ion drift velocity and its vertical changes, their initial distribution and ambipolar diffusion also determine the development of ion convergence/divergence processes. For a small magnitude of vertical wind velocity, its significant influence on the ions/electrons behavior is demonstrated, which shows the importance of both tidal wind and wind changes caused by the propagation of atmospheric gravity waves on the formation of the Es layer. In this theoretical research, it is shown that the realistic profile of the wind velocity, which takes into account the vertical component along with its zonal and meridional ones, is important for the prediction of the Es layers formation, as well as regions of ion depletion.

Occurrence Characteristics of VHF Scintillation and Equatorial Spread F over Kwajalein during Moderate Solar Activity in 2012

The occurrence probability of equatorial plasma bubbles and the associated spread F (ESF) irregularities have been derived from ground-based and space-borne measurements. In general, ESF occurrence depends on season and longitude and is high in equinoctial months and low around June solstice. In the West Pacific sector, previous statistical results show that the ESF occurrence probability increases gradually and continuously from March to August. In this study, we use trans-ionospheric VHF data received at Kwajalein Atoll in 2012 to derive the occurrence characteristics of scintillation. It is found that the occurrence probability of strong scintillation had two maxima in June and September and a minimum in July in the evening and midnight sector but only one maximum in June in the post-midnight sector. The monthly variations of scintillation occurrence at Kwajalein are different from almost all previous studies on ESF and scintillation at or near this longitude. To identify the cause for the June peak and the July minimum of scintillation, the ion density and velocity data measured by the Communication/Navigation Outage Forecasting System (C/NOFS) satellite in 2011–2012 are used to derive the ESF occurrence and the post-sunset vertical ion drift near Kwajalein. The ESF occurrence probability and the ion drift measured by the C/NOFS satellite showed two maxima in May/June and August/September and a minimum in July, verifying that the June peak and the July minimum of the VHF scintillation are realistic and caused by the similar variations in the ionospheric ion drift and density.

Modeling the Day‐To‐Day Variability of Midnight Equatorial Plasma Bubbles With SAMI3/SD‐WACCM‐X

AbstractIt is well‐known that equatorial plasma bubbles (EPBs) are highly correlated to the post‐sunset rise of the ionosphere on a climatological basis. However, when proceeding to the daily EPB development, what controls the day‐to‐day/longitudinal variability of EPBs remains a puzzle. In this study, we investigate the underlying physics responsible for the day‐to‐day/longitudinal variability of EPBs using the Sami3 is A Model of the Ionosphere (SAMI3) and the Specified Dynamics Whole Atmosphere Community Climate Model with thermosphere‐ionosphere eXtension (SD‐WACCM‐X). Simulation results on October 20, 22, and 24, 2020 were presented. SAMI3/SD‐WACCM‐X self‐consistently generated midnight EPBs on October 20 and 24, displaying irregular and regular spatial distributions, respectively. However, EPBs are absent on October 22. We investigate the role of gravity waves on upwelling growth and EPB development and discuss how gravity waves contribute to the distributions of EPBs. We found the westward wind associated with solar terminator waves and gravity waves induces polarization electric fields that map to the equatorial ionosphere from higher latitudes, resulting in midnight vertical drift enhancement and retrograde plasma flow. The upward vertical drift and retrograde flow further lead to shear flow instability and midnight plasma vortex, creating background conditions identical to the post‐sunset ionosphere. This provides conditions favorable for the upwelling growth and EPB development. The converging and diverging winds associated with solar terminator waves and midnight temperature maximum also affect the longitudinal distribution of EPBs. The absence of EPBs on October 22 is related to the weak westward wind associated with solar terminator waves.

Ionosonde and GPS total electron content observations during the 26 December 2019 annular solar eclipse over Indonesia

Abstract. We report the investigation of the ionospheric response to the passage of an annular solar eclipse over Southeast Asia on 26 December 2019 using multiple sets of observations. Two ionosondes (one at Kototabang and another at Pontianak) were used to measure dynamical changes in the ionospheric layer during the event. A network of ground-based GPS receiver stations in Indonesia was used to derive the distribution of total electron content (TEC) over the region. In addition, extreme ultraviolet (EUV) images of the Sun from the Atmospheric Imaging Assembly (AIA) instrument on board the Solar Dynamics Observatory (SDO) satellite were also analyzed to determine possible impacts of solar-active regions on the changes that occurred in the ionosphere during the eclipse. We found −1.62 and −1.90 MHz reductions (24.0 % and 27.5 % relative reduction) in foF2 during the solar eclipse over Kototabang and Pontianak, respectively. The respective TEC reductions over Kototabang and Pontianak during the eclipse were −4.34 and −5.45 TECU (24.9 % and 27.9 % relative reduction). Data from both ionosondes indicate a consistent 34–36 min delay between maximum eclipse and minimum foF2. The corresponding time delays for eclipse-related TEC reduction at these two locations were 40 and 16 min, respectively. The ionospheric F layer was found to descend with a speed of 9–19 m s−1 during the first half of the eclipse period. We also found an apparent rise in the ionospheric F-layer height near the end of the solar eclipse period, equivalent to a vertical drift velocity of 44–47 m s−1. The GPS TEC data mapping along a set of cross-sectional cuts indicates that the greatest TEC reduction actually occurred to the north of the solar-eclipse path, opposite of the direction from which the lunar shadow fell. As the central path of the solar eclipse was located just to the north of the southern equatorial ionization anomaly (EIA) crest, it is suspected that such a peculiar TEC reduction pattern was caused by plasma flow associated with the equatorial fountain effect. Net perturbations of TEC were also computed and analyzed, which revealed the presence of some wavelike fluctuations associated with the solar-eclipse event. Some of the observed TEC perturbation patterns that propagated with a velocity matching the lunar shadow may be explained in terms of nonuniform EUV illumination that arose as various active regions on the Sun went obstructed and unobstructed during the eclipse. The remaining wavelike features are likely to be traveling ionospheric disturbances (TIDs) generated by the passage of the solar eclipse on top of other diurnal factors.

Environmental, bystander and resident exposure from orchard applications using an agricultural unmanned aerial spraying system

Unmanned aerial spraying systems (UASS), i.e., unmanned aerial vehicles designed for pesticide applications, are widely used in East Asia and increasingly prevalent in other regions of the world, including North America and Europe. However, according to a recent report of the Organization for Economic Co-operation and Development, spray drift and exposure caused by these systems are not yet fully understood. In particular, there are at present no peer-reviewed reports on direct exposure of residents and bystanders to spray drift following UASS applications. This lack of data results in regulatory concerns with respect to the environment and human safety. The objective of this study was to quantify environmental, resident and bystander exposure following the application of a plant protection product to an orchard using a commercial UASS under field conditions. Using a fluorescent tracer, horizontal and vertical downwind drift data were collected and direct exposure of residents and bystanders located downwind the sprayed area to spray drift was quantified using display mannequins equipped with personal air sampling pumps. Spray drift and exposure inversely correlated with sampling height and downwind distance. Furthermore, drift and exposure were strongly influenced by wind speed and direction, albeit hardly affected by the growth stage of the trees. In addition, substantially less tracer was extracted from the filters of the air sampling pumps than from the coveralls worn by mannequins, suggesting that direct resident/bystander exposure to spray drift may predominantly occur via the dermal route. This report provides essential data on UASS spray drift potential that are relevant for environmental and health risk assessments related to these systems. The results are compared to predicted values of current regulatory models and previously reported field data on drift and exposure caused by different spraying equipment.

Optimization of Vertical GaN Drift Region Layers for Avalanche and Punch-Through Pn-Diodes

We optimized gallium nitride drift layers for high voltage and low resistance vertical electronic devices by tuning the doping concentration for a given thickness of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5~\mu \text{m}$ </tex-math></inline-formula> . The optimization procedure is based on an empirical mobility model in order to maximize the corresponding device’s power figure-of-merit with respect to the drift layers parameters. We demonstrate quasi-vertical gallium-nitride based avalanche and punch-through pn-diodes grown on sapphire substrates and we compare the results to the theoretical breakdown voltage values as a function of the drift region doping concentration and thickness. We report on a pn-diode with 545 V avalanche breakdown voltage and a specific resistance of 0.34 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{m}\Omega $ </tex-math></inline-formula> cm2 resulting in a power figure-of-merit of 874 MW / cm2 and a punch-through pn-diode with 920 V breakdown voltage, specific resistance of 0.57 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{m}\Omega $ </tex-math></inline-formula> cm2 resulting in a power figure-of-merit of 1.48 GW / cm2.

Transient Response of Polar‐Cusp Ionosphere to an Interplanetary Shock

AbstractInterplanetary (IP) shock‐driven sudden compression of the Earth's magnetosphere produces electromagnetic disturbances in the polar ionosphere. Several studies have examined the effects of IP shock on magnetosphere‐ionosphere coupling systems using all‐sky cameras and radars. In this study, we examine responses and drivers of the polar ionosphere following an IP shock compression on 16 June 2012. We observe the vertical drift and concurrent horizontal motion of the plasma. Observations from digisonde located at Antarctic Zhongshan station (ZHO) showed an ionospheric thick E region ionization and associated vertical downward plasma motion at F region. In addition, horizontal ionospheric convection reversals were observed on the Super Dual Auroral Radar Network ZHO and McMurdo radar observations. Findings suggest that the transient convective reversal breaks the original shear equilibrium, it is expected that the IP shock‐induced electric field triggers an enhanced velocity shear mapping to the E region. The horizontal motion of the plasma was attributed to only the dusk‐to‐dawn electric field that existed during the preliminary phase of sudden impulse. We also found that ionospheric convection reversals were driven by a downward field‐aligned current. The results of these observations reveal, for the first time, the immediate and direct cusp ionosphere response to the IP shock, which is critical for understanding the global response of the magnetosphere following an abrupt change in Interplanetory Magnetic Field (IMF) and solar wind conditions.

Deep Electron Density Depletion Near Sunset Terminator on St. Patrick's Day Storm and Its Impacts on Skywave Propagation

AbstractThe plasma density distribution in the equatorial and low latitude ionosphere can often be severely disturbed during active space weather events that can have paramount impacts on the long‐distance high frequency (HF) radio wave (Skywave) communications through the ionosphere. On the St. Patrick's Day storm of 17 March 2015, a deep depletion of plasma with more than two orders of magnitude was observed over a narrow longitudinal sector near the sunset terminator. The controlled SAMI2 (Sami2 is Another Model of the Ionosphere) simulations indicate that a large equatorial vertical drift around sunset terminator can produce such a deep electron density depletion and strong reinforcement of equatorial ionization anomaly. The impacts of these ionospheric density disturbances on the Skywave communication systems have been investigated using an HF propagation simulator that solves the propagation path of radio waves under given background ionospheric conditions. The results clearly demonstrate that the usable HF spectrum for Skywave communications is reduced by more than 50% over the region of depletion. Further, large areas of skip zones, where the Skywave signals are not receivable, are produced due to low ionospheric densities over this region. This study can have important applications in the planning and operation of Skywave systems during the active space weather periods.

Ionosphere response to geospace storm on 25 September 2016 over Kharkiv (Ukraine)

Instrumental observations of variations in the level of the geomagnetic field and ionospheric parameters were conducted during a weak geospace storm on September 25, 2016. It was found that a moderate magnetic storm was accompanied by variations in the level of the H component of the geomagnetic field up to 20–30 nT, as well as variations in the level of fluctuations of the horizontal components of the geomagnetic field up to ±(2–3) nT. It was revealed that the ionospheric storm was three-phase, mostly moderate. The decrease in the electron density reached a factor of 1.5, and its increase reached a factor of 2.2. The increase in the electron temperature during the negative phase of ionospheric storm did not exceed 200–300 K, while its increase during the positive phase of ionospheric storm reached 400–500 K. The ion temperature variations were within ±100 K. During the negative phases of the ionospheric storm, individual deviations in the vertical plasma drift velocity from those on a geomagnetically quiet day were observed both in the direction of decreasing the downward drift velocity (increasing the upward drift velocity at high altitudes) and vice versa. Significant (17–53 m/s) deviations in velocity variations towards positive values (decrease of downward and increase of upward drift velocity), accompanied by the rise of the F2 layer, after significant changing in the zonal component of the magnetospheric electric field (from –2 to 3.5 mV/m), contributed to the increase in the electron density and to the appearance of the positive phase of the ionospheric storm. During the positive phase, the increase in the velocity of downward plasma drift reached 9–20 m/s at altitudes above 450 km. The negative phases of the ionospheric storm were formed due to an increase in the electron and ion temperatures and a decrease in the O/N2 ratio during the storm. The generation of ionospheric storm positive phase at mid-latitudes apparently was caused by several mechanisms at once: a penetrating electric field, a meridional wind directed toward the equator, and downward plasma flows in the protonosphere. The phases of the ionospheric storm were accompanied by significant variations in the dynamic and thermal processes in the ionosphere.

Trends in runaway electron plateau partial recombination by massive H2 or D2 injection in DIII-D and JET and first extrapolations to ITER and SPARC

Experimental trends in thermal plasma partial recombination resulting from massive injection into high-Z (Ar) containing runaway electron (RE) plateaus in DIII-D and JET are studied for the purpose of achieving sufficiently low electron density () to increase RE final loss MHD levels. In both DIII-D and JET, thermal electron density is found to drop by ∼100 when the thermal plasma partially recombines, with a minimum at a vacuum vessel-averaged density in the range . RE effective resistivity also drops after partial recombination, indicating expulsion of the Ar content. The level after partial recombination is found to increase as RE current is increased. The amount of initial Ar in the RE plateau is not observed to have a strong effect on partial recombination. Partial recombination timescales of order 5 ms in DIII-D and 15 ms in JET are observed. These basic trends and timescales are matched with a 1D diffusion model, which is then used to extrapolate to ITER and SPARC tokamaks. Within the approximations of this model, it is predicted that ITER will be able to achieve sufficiently low values on time scales faster than expected RE plateau vertical drift timescales (of order 100 ms), provided sufficient or is injected. In SPARC, it is predicted that achieving significant recombination will be challenging, due to the very high RE current density. In both ITER and SPARC, it is predicted that achieving low will be easier with Ar as a background impurity (rather than Ne).

A Case of Anomalous Electric Field Perturbations in the Equatorial Ionosphere During Postsunset Hours: Insights

AbstractDuring a weak geomagnetic storm (Ap = 15) on 24 December 2014, the penetration electric field perturbations over the Indian dip equatorial sector are found to be anomalous on a number of occasions during postsunset hours. The event is anomalous as the magnitude and polarity of penetration electric fields do not obey the existing paradigm. The penetration electric field perturbations are investigated using the vertical drifts derived from the CADI (Canadian Advanced Digital Ionosonde) measurements at Tirunelveli (8.7°N, 77.7°E, dip angle: 1.7°). During this event, we observed postsunset vertical drift of ∼42 m s−1 not only at 18:10 LT but also ∼36 m s−1 at ∼21:00 LT which is anomalous. Interestingly, the dawn‐dusk component of interplanetary electric field (IEFy) is relatively less (&lt;2 mV/m) at ∼21:00 LT compared to the interval 19:30–20:30 LT (IEFy ∼3 mV/m). Despite that, the vertical drift observed over Tirunelveli is very close to zero or nominally upward during 19:30–20:30 LT. In addition, the downward drift just after 21:30 LT on this night is found to be exceptionally large (∼−60 m s−1). By combining vertical total electron content over the Indian sector with the OI 630.0 nm airglow intensity from Mt. Abu, chain of magnetometer and Los Alamos National Laboratory geosynchronous satellite particle measurements, it is suggested that the anomalous penetration electric field perturbations on this night arise from the effects of interplanetary magnetic field By and substorm.

Light detection with power and signal transmission over fiber

The Deep Underground Neutrino Experiment is a next generation long baseline (1300 km) neutrino oscillation experiment. The neutrino beam measurements will be performed by a near detector and far detector. The far detector will consist of four modules, installed 1.5 km deep underground, based on Liquid Argon Time Projection Chamber (LArTPC) technology to detect particles. The Vertical Drift (VD) LArTPC is a recent technology proposed by the DUNE collaboration for the second FD module. In VD, light collection will be optimized by embedding photon detectors within the LArTPC cathode, which is biased at −300 kV. As a result, power must arrive to the Photon Detection System and signal must be transmitted via non-conductive material. The proposed solution is to use Power-over-Fiber and Signal-over-Fiber. An intense validation of the system is being performed by the collaboration at the CERN Neutrino Platform. The design of the system and the results of the validation collected over the first half of 2022 are presented here.

Simulation of Transient Topside Layer in the Martian Ionosphere

Many Mars missions, e.g., Mariner, Viking, Mars Global Surveyor (MGS), Mars Express (MEX), and Mars Atmosphere and Volatile Evolution (MAVEN), have been launched to study the Martian atmosphere. These observations have improved our understanding of the ionosphere of Mars. Observations show that the Martian ionosphere could be divided into an M2 layer (at ~140 km altitude) and an M1 layer (at ~110 km altitude), ionized by EUV and X-ray solar radiation, respectively. However, there are still many scientific questions about the Martian ionosphere. A transient topsider layer (also called the M3 layer, at ~160–~220 km) can frequently be measured above the M2 layer in the Martian ionosphere. The statistical characteristics of the M3 layer show that it is not irradiated by solar incident radiation. Many candidate mechanisms have been suggested to explain the formation of the M3 layer. However, the method of describing or modeling the M3 layer is still one of the many open scientific questions about the Martian ionosphere. This study used a one-dimensional model, including photochemical production, loss, and dynamic transport processes to simulate the transient topside layer in the Martian ionosphere. The M3 layer was reproduced by a perturbed vertical plasma drift in this study. The enhancement of the electron temperature induced by the dynamic process of plasma could facilitate the formation of the M3 layer. Our results show that the vertical transport process of plasma might be more crucial in producing the M3 layer in the topside Martian ionosphere.