Penetration Of Electric Field Research Articles

Systematical Analyses of Global Ionospheric Disturbance Current Systems Caused by Multiple Processes: Penetration Electric Fields, Solar Wind Pressure Impulses, Magnetospheric Substorms, and ULF Waves.

We present the first systematic analysis of global ionospheric disturbance current systems caused by multiple processes of solar and magnetospheric origin, including reorientations of the interplanetary magnetic field (IMF), sudden changes in the solar wind dynamic pressure, magnetospheric sawtooth substorms, and ultralow frequency (ULF) waves. Measurements from global magnetometer networks are used to derive the equivalent disturbance currents from the polar cap to the equator. A surprising result is that the equivalent disturbance current systems are very similar, although the driving processes are completely different. The equivalent disturbance current system in response to IMF reorientation or substorm onset is characterized by a large vortex on the dayside and evening sector and a smaller vortex near dawn, and the polarity of the current vortices depends on the IMF direction. The equivalent disturbance current system caused by a sudden change in the solar wind pressure or by ULF waves consists of a single vortex at middle and low latitudes and a very small vortex above ~60° magnetic latitude near dawn. The similar disturbance current systems caused by different solar wind and magnetospheric processes suggest that the global distribution of the ionospheric currents is determined by the intrinsic property of the ionosphere. The global current system takes only ~1 min to completely reconstruct, indicating that the current system can reach a new steady state within 1 min. A scenario is proposed to explain the global distribution and fast reconstruction of the current systems.

Facile Synthesis of Ant-Nest-Like Porous Duplex Copper as Deeply Cycling Host for Lithium Metal Anodes.

Suppressing the dendrite formation and managing the volume change of lithium (Li) metal anode have been global challenges in the lithium batteries community. Herein, a duplex copper (Cu) foil with an ant-nest-like network and a dense substrate is reported for an ultrastable Li metal anode. The duplex Cu is fabricated by sulfurization of thick Cu foil with a subsequent skeleton self-welding procedure. Uniform Li deposition is achieved by the 3D interconnected architecture and lithiophilic surface of self-welded Cu skeleton. The sufficient space in the porous layer enables a large areal capacity for Li and significantly improves the electrode-electrolyte interface. Simulations reveal that the structure allows proper electric field penetration into the connected tunnels. The assembled Li anodes exhibit high coulombic efficiency (97.3% over 300 cycles) and long lifespan (>880 h) at a current density of 1mA cm-2 with a capacity of 1 mAh cm-2 . Stable and deep cycling can be maintained up to 50 times at a high capacity of 10 mAh cm-2 .

Longitudinal Responses of the Equatorial/Low‐Latitude Ionosphere Over the Oceanic Regions to Geomagnetic Storms of May and September 2017

AbstractThis study presents the longitudinal dependence of responses of the equatorial/low‐latitude ionosphere over the oceanic regions to geomagnetic storms of 28 May and 8 September 2017. We investigated the interplanetary origins of the storms. Total electron content (TEC) data were obtained from Global Navigation Satellite System stations, located around the oceanic areas in the equatorial/low‐latitude regions. The Rate of change of TEC Index (ROTI) was used as a proxy for ionospheric irregularities over the study locations. Further, variations of the horizontal component of the Earth's magnetic fields, obtained from ground‐based magnetometers were studied. We used ionospheric disturbance currents, polar cap and auroral electrojet indices to monitor the storm time electric fields. The May 2017 storm was driven by sheath and magnetic cloud fields, while the September 2017 storm was driven by sheath fields. We observed a comparative dominance of TEC intensities over the Oceans than over the landlocked areas. Empirically, our results validated a theoretical suggestion of the existence of a dynamic ocean‐ionosphere coupling made by Godin et al. (2015, http://10.0.4.162/s40623-015-0212-4). Prompt Penetration Electric Fields (PPEF) was observed to be a key factor that controls TEC responses to storms. PPEFs caused TEC enhancements, mainly over the Pacific Ocean longitudes during the May 2017 storm and enhanced TEC over the Atlantic Ocean and the Pacific Oceans longitudes during the September 2017 storm. These PPEFs triggered irregularities over the Pacific Ocean longitudes, particularly during the main phase of May 2017 storm. Irregularities were generally inhibited by the September 2017 storm.

High-Sensitivity, Quantified, Linear and Mediator-Free Resonator-Based Microwave Biosensor for Glucose Detection.

This article presents a high-sensitivity, quantified, linear, and mediator-free resonator-based microwave biosensor for glucose sensing application. The proposed biosensor comprises an air-bridge-type asymmetrical differential inductor (L) and a center-loaded circular finger-based inter-digital capacitor (C) fabricated on Gallium Arsenide (GaAs) substrate using advanced micro-fabrication technology. The intertwined asymmetrical differential inductor is used to achieve a high inductance value with a suitable Q-factor, and the centralized inter-digital capacitor is introduced to generate an intensified electric field. The designed microwave sensor is optimized to operate at a low resonating frequency that increases the electric field penetration depth and interaction area in the glucose sample. The microwave biosensor is tested with different glucose concentrations (0.3–5 mg/ml), under different ambient temperatures (10–50 °C). The involvement of advanced micro-fabrication technology effectively miniaturized the microwave biosensor (0.006λ0 × 0.005λ0) and enhanced its filling factor. The proposed microwave biosensor demonstrates a high sensitivity of 117.5 MHz/mgmL-1 with a linear response (r2 = 0.9987), good amplitude variation of 0.49 dB/mgmL-1 with a linear response (r2 = 0.9954), and maximum reproducibility of 0.78% at 2 mg/mL. Additionally, mathematical modelling was performed to estimate the dielectric value of the frequency-dependent glucose sample. The measured and analyzed results indicate that the proposed biosensor is suitable for real-time blood glucose detection measurements.

Geomagnetic Activity Control of Irregularities Occurrences Over the Crests of the African EIA

AbstractThis paper investigated the behavior of ionospheric irregularities over the African equatorial ionization anomaly (EIA) crests during intense geomagnetic storms that occurred from 2012 to 2015. Irregularities were monitored using the rate of change of TEC index along with variations of the horizontal component of the Earth's magnetic field (H) and ionospheric electric current disturbance (Diono). The predictive capability of the Prompt Penetration Equatorial Electric Field Model (PPEFM) was assessed by comparing prompt penetration electric field (PPEF) inferred from interplanetary electric field and Diono with PPEF derived from the PPEFM, with emphasis on how well the model reproduced enhancement/reduction in the prereversal enhancement (PRE). Eastward PPEF triggered short duration irregularities on 23 April 2012, 17 March 2013, and 20 February 2014 while westward electric field reduced them thereafter. The PPEFM rightly predicted enhancement (reduction) in PRE on 17 March 2013 (19 February 2014) when irregularities were triggered (inhibited). It, however, showed no change in the PRE on 23 April 2012 and 20 February 2014. During the storms recoveries, irregularities were always inhibited/reduced over the trough by westward disturbance dynamo and the inhibition lasted longer during the superstorm of March 2015. Also, there was a hemispheric asymmetry in irregularities over the African EIA crests. On 16–17 July 2012, 15 November 2012, and 19 March 2013, there were differences in irregularities behavior. On these days, the asymmetry of the postsunset crests was pronounced in both hemispheres.

Geomagnetic Storm‐Induced Plasma Density Enhancements in the Southern Polar Ionospheric Region: A Comparative Study Using St. Patrick's Day Storms of 2013 and 2015

AbstractThe occurrence of St. Patrick's Day (17 March) geomagnetic storms during two different years (2013 and 2015) with similar solar flux levels but varying storm intensity provided an opportunity to compare and contrast the responses of the ionosphere‐thermosphere (IT) system to different levels of geomagnetic activity. The evolution of positive ionospheric storms at the southern polar stations Bharati (76.6°S MLAT) and Davis (76.2°S MLAT) and its causative connection to the solar wind driving mechanisms during these storms has been investigated in this paper. During the main phase of both the storms, significant enhancements in TEC and phase scintillation were observed in the magnetic noon/ midnight period at Bharati and Davis. The TEC in the midnight sector on 17 March 2015 was significantly higher compared to that on 17 March 2013, in line with the storm intensity. The TEC enhancements during both the storm events are associated with the formation of the storm‐enhanced densities (SEDs)/tongue of ionization (TOI). The strong and sustained magnetopause erosion led to the prevalence of stronger storm time electric fields (prompt penetration electric field (PPEF)/subauroral polarization streams (SAPS)) for long duration on 17 March 2015. This combined with the action of neutral winds at midlatitudes favored the formation of higher plasma densities in the regions of SED formation on this day. The same was weaker during the 17 March 2013 storm due to the fast fluctuating nature of interplanetary magnetic field (IMF) Bz. This study shows that the duration and extent of magnetopause erosion play an important role in the spatiotemporal evolution of the plasma density distribution in the high‐midlatitude ionosphere.

Experimental Determination of the Conditions Associated With “Zebra Stripe” Pattern Generation in the Earth's Inner Radiation Belt and Slot Region

AbstractThe “zebra stripes” are peaks and valleys commonly present in the spectrograms of energetic particles trapped in the Earth's inner belt and slot region. Several theories have been proposed over the years to explain their generation, structure, and evolution. Yet, the plausibility of various theories has not been tested due to a historical lack of ground truth, including in situ electric field measurements. In this work, we leverage the new visibility offered by the database of Van Allen Probes electric drift measurements to reveal the conditions associated with the generation of zebra stripe patterns. Energetic electron fluxes by the Radiation Belt Storm Probes Ion Composition Experiment between 1 January 2013 and 31 December 2015 are systematically analyzed to determine 370 start times associated with the generation of zebra stripes. Statistical analyses of these events reveal that the zebra stripes are usually created during substorm onset, a time at which prompt penetration electric fields are present in the plasmasphere. All the pieces of experimental evidence collected are consistent with a scenario in which the prompt penetration electric field associated with substorm onset leads to a sudden perturbation of the trapped particle drift motion. Subsequent drift echoes constitute the zebra stripes. This study exemplifies how the analysis of trapped particle dynamics in the inner belt and slot region provides complementary information on the dynamics of plasmaspheric electric fields. It is the first time that the signature of prompt penetration electric fields is detected in near‐equatorial electric field measurements below L = 3.

Temporally Interfering TMS: Focal and Dynamic Stimulation Location.

In this study, we present a temporal interference (TI) concept to achieve focal and steerable stimulation in the targeted brain area through transcranial magnetic stimulation (TMS). This method works by inducing two high-frequency electric fields with a slight frequency difference via two independent coils. The intrinsic nonlinear nature of the nerve membrane, which acts as a low-pass filter, does not allow the nerve to engage at high frequencies. Instead, neurons at the intersection of two electric fields can follow the frequency difference of the two fields. For 3D MRI-derived head models, the finite element method is used to compute the electric field induced by the time-varying magnetic field along with the electric field penetration depth and the activated volume for the specific coil parameters. A deeper stimulation with an acceptable spatial spread can be obtained by controlling the intersection of the fields by finding the optimal position and orientation of the two coils. Moreover, by changing the voltage ratio of the coils, and not their mechanical orientation, the intended area can be dynamically driven. The computational results show that the TI technique is an efficient approach to resolve the electric field depth-focality trade-off, which can be a reasonable alternative to complex coil designs. The system proposed in this paper shows a great promise for a more dynamic and focused magnetic stimulation.

철근 콘크리트 구조 내 포설 케이블의 HEMP 결합 근사 해석 방법

High-power electromagnetic fields, which are used as one of the core weapon systems in electronic warfare, can cause malfunctions in communication and power systems. Therefore, it is necessary to study their effects on civil and military facilities. In this paper, an approximated method for analyzing the voltage induced in a cable, placed inside a building, by HEMP was proposed. To calculate the electric field penetrating into the building, an equivalent medium for a multilayer reinforced concrete structure was implemented, and its transmission and reflection characteristics were obtained. The penetration level of the E1 pulse and the load voltage of the cable for unit voltage sources at each load were calculated. Subsequently, the coupling voltage was obtained and verified.

Observation of Anomalously Strong Penetration of Terahertz Electric Field Through Terahertz-Opaque Gold Films Into a GaAs/AlGaAs Quantum Well

We observe an anomalously high electric field of terahertz (THz) radiation acting on a two-dimensional electron gas (2DEG) placed beneath a thin gold film, which, however, is supposed to be opaque at THz frequencies. We show that the anomalously strong penetration of the THz electric field through a very high conductive gold film emerges if two conditions are fulfilled simultaneously: (i) the film’s thickness is less than the skin depth and (ii) the THz electric field is measured beneath the film at distances substantially smaller than the radiation wavelength. We demonstrate that under these conditions, the strength of the field acting on a 2DEG is almost the same as it would be in the absence of the gold film. The effect is detected for macroscopically homogeneous perforation-free gold films illuminated by THz laser radiation with a spot smaller than the film area. This eliminates the near field of the edge diffraction as a possible cause of the anomalous penetration. The microscopic origin of the effect remains unexplained in its details, yet. The observed effect can be used for the development of THz devices based on two-dimensional materials requiring robust highly conducting top gates placed at less than nanometer distance from the electron gas location.

Ionospheric response to the 26 August 2018 geomagnetic storm using GPS-TEC observations along 80° E and 120° E longitudes in the Asian sector

This study investigates the response of equatorial and low latitude ionosphere during an intense geomagnetic storm of 26 August 2018 (Dst min = −206 nT) using the TEC observations from two chains of GPS stations along 80° E and 120° E longitudes in the Asian sector. These GPS networks include Waltair and four IGS stations (SGOC, IISC, HYDE and LCK4) along 80° E and five IGS stations (SHAO, TCMS, CKSV, PIMO and PGEN) along 120° E longitudes. The [O]/[N2] observations from GUVI have also been used for the present study. Large positive storm effect is observed in the day-time TEC for three consecutive days starting from main phase until the late recovery phases of the storm (26th to 28th August 2018). Significant difference has been observed in TEC response between 80° E and 120° E longitudes particularly during the recovery phase of the storm which is further confirmed by GIM derived TEC. The equatorial ionization anomaly (EIA) exhibit strong enhancement around the anomaly crests during the main phase of the storm. This enhancement in the EIA crest is also evidenced in GIM CODE TEC maps. The positive storm effect during the main and recovery phases is mainly attributed to the eastward prompt penetration electric fields in addition to strongly enhanced ratio of thermosphere neutral composition i.e. [O]/[N2], the results of which are presented in this paper.

Penetration electric fields observed at middle and low latitudes during the 22 June 2015 geomagnetic storm

Prompt penetration electric fields were detected during the intense geomagnetic storm on 22 June, 2015 by the HF Doppler sounders at middle and low latitudes; Prague (Czech Republic), Iitate, Oarai, Onna (Japan), and Zhongli (Republic of China). The storm was initiated by the storm sudden commencement (SC) at 1833 UT, immediately followed by the main phase with the minimum SYM-H of − 139 nT at 2017 UT. The convection electric field was found to be up to 5.1 mV/m at low latitudes, which is enough to cause ionospheric disturbances such as the enhancement of the total electron content, equatorial ionization anomaly and so on. The electric fields of the SC and main phase are westward in the night (0330 MLT), while eastward in the evening (1930 MLT). The main phase electric field intensified the eastward equatorial electrojets (EEJ) at Huancayo in South America on the dayside (1330 MLT) and the westward EEJ on the nightside at Guam in the western Pacific (0330 MLT) and Tirunelveli in India (00 MLT). The eastward direction of the evening-time electric field agrees with a feature of the evening anomaly of the penetration electric field, while the intensity is suppressed because of the sunlit condition in the evening in the summer solstice. The sudden northward turning of the interplanetary magnetic field (IMF) caused a transition from the main phase to the recovery phase, when the EEJ turned into the counterelectrojet (CEJ). It was found that the HF Doppler sounders detected an impulsive eastward overshielding electric field at 2005 UT on the nightside during the northward IMF-driven CEJ with the duration of 17 min and intensity of 8.0 mV/m at Iitate (0500 MLT) and 11.8 mV/m at Prague (2130 MLT). The impulsive overshielding electric field was accompanied by the anti-sunward plasma flows at middle latitude (50°–60° GML) equatorward of the dusk sunward convection as observed with SuperDARN, which signifies intensification of the Region-2 field-aligned currents at the flow reversal. Substorm signatures are identified with intensified westward auroral electrojet and magnetic dipolarization as detected by the geosynchronous orbit satellite, ETS-VIII. Consequently, the stormtime substorm may provide strong overshielding electric fields to the middle latitude ionosphere on the nightside.

Influence of geomagnetic storms on the mid latitude D and F2 regions

The signal amplitude of 22.1 kHz Very Low Frequency (VLF) waves, transmitted from the radio station Skelton, UK (GQD at 54.7 0 N, 2.8 0 W) and received at South France station (SID, Sudden Ionospheric Disturbance monitoring station at 46 0 N, 2 0 E) is studied for the effect of geomagnetic storms on the lower ionosphere. The VLF parameters, D-Layer Preparation Time (DLPT) depth and Mid-Day Peak (MDP) have been used to study the response of D-region to the geomagnetic storms occurred during the equinox months of 2012-2015. The two parameters recorded enhancement on the storm day and subsequent days. A shift in the sunrise Terminator Time is observed for the geomagnetic storms for which Sudden Commencement (SC) occurred during the day lit hours on the previous day. The observed effect of the geomagnetic storms on the mid latitude D-region is due to the precipitation of high energy particles. The response of F 2 -region to geomagnetic storms is studied using the f o F 2 data at Dourbes (50.1 0 N, 4.6 0 E), Belgium which is near the mid-point of the GQD-South France VLF path. The percentage of deviation of f o F 2 from the quiet day values, Df o F 2 is found to undergo positive and negative changes. The positive storm effect during daytime is mainly due to the penetration electric field and strong negative phase during both day time and night time is due to depleted [O]/[N 2 ] ratios.

An Efficient Noninvasive Neuromodulation Modality for Overactive Bladder Using Time Interfering Current Method.

The present study aimed to evaluate a new tibial nerve stimulation (TNS) modality, which uses interferential currents, in terms of the stimulation electric field penetration efficiency into the body and physiological effectiveness. In silico experiments were performed to analyze the penetration efficiency of proposed interferential current therapy (ICT). Based on this, we performed in vivo experiments to measure excitation threshold of ICT for the tibial nerve, which is related to stimulation field near the nerve. Regarding analysis of the physiological effectiveness, in vivo ICT-TNS was performed, and changes in bladder contraction frequency and voiding volume were measured. The penetration efficiency and physiological effectiveness of ICT were evaluated by comparison with those of conventional TNS using transcutaneous electrical nerve stimulation (TENS). Simulation results showed that ICT has high penetration efficiency, thereby generating stronger field than TENS. These results are consistent with the in vivo results that nerve excitation threshold of ICT is lower than that of TENS. Moreover, ICT-TNS decreased contraction frequency and increased voiding volume, and its performance was profound compared with that of TENS-TNS. The proposed ICT is more efficient in inducing the stimulation field near the tibial nerve placed deep inside the body compared with conventional TENS and shows a good clinical effectiveness for TNS. The high efficiency of ICT increases the safety of noninvasive neurostimulation; therefore, it has clinical potential to become a promising modality for TNS to treat OAB and other peripheral neurostimulations.

Large-Scale Ionospheric Irregularities Detected by Ionosonde and GNSS Receiver Network

Large-scale ionospheric irregularities, which occurred on September 8, 2017, were detected by the ionosonde and the Global Navigation Satellite System (GNSS) receiver network in this letter. The Wuhan ionospheric sounding system (WISS), deployed at Puer (PUR, 22.7°N, 101.05°E), Leshan (LSH, 29.6°N, 103.7°E), and Zhangye (ZHY, 39.4°N, 100.13°E), detected these large-scale ionospheric irregularities. The 2-D maps of the rate of the GNSS total electron content (TEC) index (ROTI) further confirmed that the large-scale ionospheric irregularities can cover a broad area (from the equator to middle latitude, ~80°E to ~120°E, ~20°N to ~45°N). The ionospheric variation recorded by the WISS shows that the large-scale ionospheric irregularities were driven by the super eastward electric field, which was formed by the eastward prompt penetration electric field during a storm superimposed on the normal prereversal enhancement during the postsunset hours. Moreover, observations by the WISS show the higher the latitudes at which the ionospheric irregularities/spread F occurred, the shorter the duration time.

Large‐Scale Ionospheric Disturbances During the 17 March 2015 Storm: A Model‐Data Comparative Study

AbstractThis paper presents a detailed model‐data comparative study of the 17 March 2015 geomagnetic storm using the high‐resolution version of the thermosphere‐ionosphere‐electrodynamic general circulation model and the total electron content observations from a dense global navigation satellite system network. Driven by time‐dependent high‐latitude ionospheric convection and auroral precipitation inputs, together with an empirically defined subauroral plasma stream (SAPS) field, our simulation reproduce many observed storm‐related ionospheric phenomena, including large‐scale traveling ionospheric disturbances over Europe, the effects of prompt penetration electric field over South and Central America, and the formation of a storm‐enhanced density (SED) plume across the continental United States. Our simulation results reaffirm a number of important characteristics concerning the SED plume: (1) enhanced background ionospheric density is a necessary but not sufficient condition, and enhanced ion drift is required to form the SED plume; (2) the SAPS flow channel does not directly transport the plasma from midnight to postnoon via dusk to form the SED plume, instead, the SED plume is formed at the equatorward and westward edge of the SAPS channel; and (3) the SED plume appears to subcorotate with respect to the Earth.

Ionospheric TEC disturbances over China during the strong geomagnetic storm in September 2017

From September 7 to 8, 2017, a G4-level strong geomagnetic storm occurred, which seriously impacted on the Earth’s ionosphere. In this work, the global ionospheric maps released by Chinese Academy of Sciences are used to investigate the ionospheric responses over China and its adjacent regions during the strong storm. The prominent TEC enhancements, which mainly associated with the neutral wind and eastward prompt penetration electric field, are observed at equatorial ionization anomaly crests during the main phase of the storm on 8 September 2017. Compared with those on 8 September, the TEC enhancements move to lower-latitude regions during the recovery phase on 9 September. A moderate storm occurred well before the start of the strong storm causes similar middle-latitude TEC enhancements on 7 September. However, the weak TEC depletion is observed at middle and low latitude on 9–10 September, which could be associated with the prevailing westward disturbance electric field or storm-time neural composition changes. In addition, the storm-time RMS and STD values of the ionospheric TEC grids over China increase significantly due to the major geomagnetic storm. The maximum of the RMS reaches 12.0 TECU, while the maximum of the STD reaches 8.3 TECU at ~04UT on 8 September.

Photonic cavity enhanced high-performance surface plasmon resonance biosensor

Herein we propose a novel strategy to enhance surface plasmon resonance (SPR) by introducing a photonic cavity into a total-internal-reflection architecture. The photonic cavity, which is comprised of a highly reflective photonic crystal (PC), defect layers, and a gold (Au) film, enables Fabry–Perot (FP) resonances in the defect layers and therefore narrows the SPR resonance width in the metallic surface as well as increases the electric field intensity and penetration depth in the evanescent region. The fabricated sensor exhibits a 5.7-fold increase in the figure of merit and a higher linear coefficient as compared with the conventional Au-SPR sensor. The demonstrated PC/FP cavity/metal structure presents a new design philosophy for SPR performance enhancement.

Ionospheric response to the June 2015 geomagnetic storm in the South American region

The ionospheric dynamics in the South America (SA) sector during geomagnetic disturbed period from 21 to 24 June 2015 is investigated through ground ionosonde stations and Global Navigation Satellite System (GNSS) receivers, supported by Very Low Frequency (VLF) and magnetometer data. These disturbances were caused by 3 interplanetary shocks (IS) derived from 3 consecutives coronal mass ejections (CME) from the same solar active region; the first two CME were caused by filament eruptions, and the third was a much larger full halo CME, associated with a M2.6 solar flare. The first 2 shocks were compressive and did not cause an immediate response to the ionosphere in the analyzed region, while the third shock increased considerably the electron density from low to high-latitudes, triggering the second strongest geomagnetic storm of the 24th solar cycle. It was possible to observe the expansion of the crest of equatorial ionospheric anomaly (EIA) at midlatitudes and high-latitudes mainly due to prompt penetration electric field (PPEF) during the main phase and the recovery phase of the geomagnetic storm during the day.

The effect of geomagnetic storms on the total electron content over the low latitude Saudi Arab region: a focus on St. Patrick’s Day storm

The present paper investigates the ionospheric response to the severe geomagnetic storms on St. Patrick’s Day (17 March 2015) and the strong geomagnetic storm (7 October 2015) over the low latitude Saudi Arab region. The GNSS-TEC observations over low latitude RASH station ($28^{\circ}29'\mbox{N}$, $34^{\circ}46'\mbox{E}$) in Saudi Arab confirms that the spatial-temporal alterations over the region not only solely depends on the low latitude electrodynamics but also relies on the high and mid electrodynamics. During the St. Patrick’s Day storm, minimum Dst has reached to −223 nT with AE enhancement up to 2215 nT and VTEC values shown maximum enhancement of 250.16% with comparison to average quiet days VTEC, which is known as the positive effect of geomagnetic storm. The positive response of the VTEC has been observed over the region due to the coexistence of Prompt penetration electric field (PPEF) with the prevailed long duration Disturbance dynamo electric field (DDEF). The F2 layer gets uplifted with the enhanced fountain effect through the equatorial E × B drift, which is observed with the enhancement in hmF2 and enhancement in O/N2 ratio. Concerning the strong geomagnetic storm event on 7 October 2015, minimum Dst has reached to −124 nT with AE enhancement up to 1209.30 nT and VTEC values shown minimum decrement of $-72.14\%$ as compared to the average quiet days VTEC, which is known as the negative effect of geomagnetic storm. The negative response of VTEC has been observed during the main phase of the storm, possibly due to the consequences of suppressed equatorial ionization anomaly (EIA) over the observatory station. The negative response has been described by the downward movement of F2 layer with apparent reduction in hmF2 and depletion in O/N2 ratio over the low latitude region. The results during the storm period also demonstrate that the intensity of amplitude scintillation is enhanced over the low latitude region whose magnitude depends on the severity of the geomagnetic storm.