Electron Density Perturbations Research Articles

On anomalous transport of multi-species plasma associated with the resistive ballooning and resistive drift waves driven turbulence

Anomalous transport of multi-species plasma related to the resistive ballooning and resistive drift wave turbulence is considered in a “cold” ion approximation. It is found that similar to the resistive drift wave turbulence [see A. R. Knyazev and S. I. Krasheninnikov, Phys. Plasmas 31, 012502 (2024); and S. I. Krasheninnikov and R. D. Smirnov, Phys. Plasmas (to be published)] the addition of the ballooning drive does not change the main features of anomalous transport of the multi-species plasma: (i) The transport of all ion species is described as a transport of the passive scalars in the turbulent field of the electrostatic potential and electron density perturbation; (ii) the density of ion species with a larger ratio of the mass to charge has the tendency to the accumulation/depletion in the vortices of plasma flow; and (iii) the cross-field transport of all plasma species (including electrons and ions) is described by the same anomalous transport coefficient.

Fe2+-NTA synergized UV254 photolytic defluorination of perfluorooctane sulfonate (PFOS): Enhancing through intramolecular electron density perturbation via electron acquisition

Perfluorooctane sulfonate (PFOS) is a persistent organic pollutant posing a risk in environmental persistence, bioaccumulation and biotoxicity. This study was to reach a comprehensive and deeper understanding of PFOS elimination in a UV254 photolytic treatment with the co-presence of Fe2+ and nitrilotriacetic acid trisodium salt (NTA). PFOS defluorination was noticeably enhanced in the UV/Fe2+-NTA treatment compared with UV/NTA, UV/Fe2+ and our previously studied UV/Fe3+ treatments. UV–vis, FTIR, and UPLC/MS-MS results indicated the formation of PFOS-Fe2+-NTA complex in PFOS, Fe2+ and NTA mixture. The transition energy gap of PFOS-Fe2+-NTA decreased below the excitation energy supplied by UV254 irradiation, corresponding with red shift appearing in UV–vis scanning spectrum. This favored intramolecular electron transfer from Fe2+-NTA to PFOS under UV254 irradiation to form electron-accepting PFOS. Molecular electrostatic potential and atom charge distribution analyses suggested electron density rearrangement and perturbation in the perfluorinated carbon chain of electron-accepting PFOS, leading to the decrease in bond dissociation energies. Intermediate products detection suggested the parallel defluorination pathways of PFOS desulfonation, middle carbon chain scission and direct C-F cleavage. NTA exhibited crucial functions in the UV/Fe2+-NTA treatment by holding Fe2+/Fe3+ in soluble form as a chelant and favoring water activation to generate hydrated electrons (eaq−) under UV irradiation as a photosensitizer. Fe2+ acting as the conduit for electron transfer and the bridge of PFOS anion and NTA was thought functioning best at 200 µM in this study. The degree of UV/Fe2+-NTA -synergized PFOS defluorination also depended on eaq− yield and UV254 photon flux. The structure dependence on the electron transfer process of PFOS and PFOA was explored incorporating molecular structure descriptors. Because of possessing greater potential to acquire electrons or less likeliness to donate its electrons than PFOA, PFOS exhibited faster defluorination kinetics in the published “reduction treatments” than “oxidation” ones. Whereas, PFOA defluorination kinetics were at similar level in both “reduction” and “oxidation” treatments.

Performance of the double-thin-shell approach for studying nighttime medium-scale traveling ionospheric disturbances using two dense GNSS observation networks in Japan

Electrodynamic coupling between the ionospheric E and F regions is widely recognized as the underlying mechanism for generating medium-scale traveling ionospheric disturbances (MSTIDs) during nighttime at midlatitudes. Recently, the double-thin-shell approach has proven to be a useful tool for studying the E–F coupling. By using total electron content (TEC) measurements, this approach enables the simultaneous reconstruction of electron density perturbations in both the E and F regions with broad and continuous coverage. However, the current reconstruction performance is limited when using only GPS-TEC measurements from GEONET, a dense network of ground-based Global Navigation Satellite System (GNSS) receivers over Japan. The expansion of available data sources and the integration of multi-GNSS observation data are considered important to enhance the double-thin-shell model. Fortunately, SoftBank Corp., a Japanese telecommunications provider, has recently developed a dense independent GNSS observation network to improve positioning services. In this paper, we analyze the potential of the improved double-thin-shell approach and emphasize the importance of incorporating multi-GNSS observation data from both GEONET and SoftBank networks. The solvability analysis, simulation, and observation results collectively indicate a substantial improvement in the spatiotemporal resolution. Specifically, the longitudinal and latitudinal resolution is improved from 0.15° to 0.1° in the E region, and from 0.5° to 0.3° in the F region. The temporal resolution is also improved from 2 to 1 min. In addition, significant improvements have been achieved in the reconstruction performance, particularly for the E region under complex background conditions. Based on these assessments, we conclude that the incorporation of GEONET and SoftBank GNSS observation data holds significant potential for improving the double-thin-shell model and advancing our understanding of MSTIDs.Graphical abstract

Occurrence of ionospheric scintillations under different solar and geomagnetic conditions over low latitude station Varanasi

In the present study, occurrences of amplitude scintillations during the ascending phase of the 25th solar cycle from November 2020 to March 2023 are studied over the equatorial anomaly region Varanasi (latitude 25.31° N, longitude 82.97° E, magnetic dip Lat. 16.2° N). Multi-frequency Global navigation satellite system (GNSS) receiver is used to study the occurrence of amplitude scintillation index S4. Diurnal, monthly, and seasonal occurrence characteristics of the S4 index are presented. The scintillation occurrence is observed during nighttime and daytime but is more probable during nighttime. It is observed that maximum scintillation occurred during the equinox season for the solar moderate period whereas the highest occurrence is in summer during the low solar activity period. The highest scintillation occurrences during the summer solstice for a period of low solar activity condition is rare and could be attributed to the gravity waves (GWs) generation due to the weather phenomena in the lower atmosphere. GWs could act as a seeding perturbation in electron density, affecting the growth of ionospheric irregularities through Rayleigh-Taylor instability. The solar flux index (F10.7) is compared with the percentage occurrence of scintillation for the low and moderate solar activity periods to observe the effect of solar activity on scintillation occurrences. Overall, the scintillation occurrence increases with increasing solar activity. To study the effect of geomagnetic storms on scintillations, we have considered seven moderate and intense geomagnetic storms grouped in three categories that occurred during solar cycle 25. It is observed that the occurrence of scintillations is enhanced for the storms with the recovery phase starting at post-midnight. The probability of occurrence of scintillation during the night hours is decreased when the geomagnetic storm occurs during the daytime.

Modeling of Solar Eclipse effects on the sub-ionospheric VLF/LF signals observed by multiple stations over Japan

We present the numerical modeling of field amplitude perturbations for two VLF/LF transmitters (JJI: 22.2 kHz, JJY: 40.0 kHz) signals recorded at six places (UEC-VLF network) in Japan during the Annular Solar Eclipse of 2012 (ASE-2012). We determine the characteristics of the D-region ionospheric perturbation according to the antumbra and penumbral shadow of the annular solar eclipse. A space–time dependent 2-Dimensional Elliptical Gaussian distribution Model (2DEGM) is introduced to get the effect of ASE-2012 on the Wait’s D-region parameters, such as effective VLF/LF reflection height (h′) and sharpness factor (β). The Long Wave Propagation Capability (LWPC) code is used to simulate the VLF signal amplitude profile with the help of modelled Wait’s parameters. A method of comparison of observed and LWPC simulated VLF signal amplitude across all the considered signal propagation paths is introduced to estimate final 2DEGM related parameters and hence, to model D-region electron density perturbations during ASE-2012. Using 2DEGM + LWPC, (i) we consistently simulate the observed VLF signal amplitude profiles for almost all the propagation paths of UEC-VLF network and (ii) evaluate the percentage change in D-region electron density due to ASE-2012.

Large-scale traveling ionospheric disturbances over central and eastern Europe during moderate magnetic storm period on 22–24 September 2020

We present the results of ground based remote sensing observations of large-scale traveling ionospheric disturbances (LSTIDs) occurring during the moderate magnetic storm evolution (22–24 September 2020) over central and eastern Europe. Three ionosondes located in Juliusruh, Pru˚honice and near Kharkiv, and the Kharkiv incoherent scatter radar were employed to study temporal and spatial LSTID signatures in ionospheric F2 peak density and height and electron density variations at the heights of 100–300 km. Two types of LSTIDs are detected, which are originated during enhancement in auroral activity (2 events) and local sunrise terminator passage (3 events) from the ionosonde data. The magnetic storm-related LSTIDs exhibit equatorward propagation with the horizontal phase velocities of 546 m/s and 576 m/s, similar dominant periods of 135–150 min and 165–180 min over all three sites and a longitudinal dependence in fractional (relative) amplitudes of electron density perturbation. The solar terminator induced LSTIDs demonstrate the variety in both relative amplitudes and dominant periods over different locations. They have a westward apparent horizontal phase velocities of 288–345 m/s, which are close to the solar terminator velocity at ionospheric heights. Employment of incoherent scatter data enabled the detection of additional LSTIDs over Ukraine with the periods in a broader range of 41–168 min, an establishment of phase and onset differences for the oscillations in the ionospheric F2 peak electron density and height.

Simulations of Reflectometer Response to ITER Plasma Perturbations Caused by Alfvén Modes

The KINX and VENUS codes were used for simulation of the baseline inductive and steady-state scenarios of the ITER tokamak operation. The perturbations of plasma electron density and magnetic field caused by the Alfvén modes were calculated in the flux coordinates for these scenarios. The perturbation fields obtained were converted into the engineering coordinates in order to calculate the propagation of probe electromagnetic radiation of the reflectometer using the two-dimensional full-wave TAMIC RτX code in the expected geometry of the experiment. The calculations performed show that for the baseline inductive scenario, in the case of reflection of the extraordinary wave at the lower cutoff frequency from the high magnetic field side, the electric field relative perturbations of the reflected reflectometer signal correspond to the margin of linear range of the diagnostics operation or even go out of this range. It was found that in a number of scenarios, not only the electron density perturbations, but also the magnetic field perturbations significantly contribute to the total signal perturbations that makes even more difficult the further data interpretation. Another possible problem is the narrow frequency range of probing frequencies where the Alfvén mode can be observed. In addition to simulating the reflection of electromagnetic waves from plasma, it was analyzed also the possibility of measuring the Alfvén modes parameters when the extraordinary wave pass through the plasma in the transparency window between the upper and lower cutoff frequencies of the extraordinary wave (refractometry). It is shown that at the fundamental frequency, the phase perturbations range from 3 to 60 degrees, which makes it impossible to use the amplitude-modulated refractometer for analyzing signals. The “synthetic diagnostics” approach was used, which showed itself well for simulating the operation of reflectometers at plasma facilities.

Experimental study of core MHD events in thousand-second improved confinement plasma on the EAST tokamak

Recently, stationary plasma with a world-record pulse length of 1056 s was achieved on the Experimental Advanced Superconducting Tokamak (EAST). In this work, the core magnetohydrodynamics (MHD) events as well as mode coupling processes have been investigated in EAST long pulse operation with electron heating dominant and pure radio frequency wave heating low collisionality, by using several diagnostics and the nonlinear numerical code M3D together. A saturated m/n = 1/1 kink mode was observed in the core region, where a stable internal transport barrier was found in the electron temperature channel. The frequencies and 2D structures of these modes were studied by a combination of soft X-ray (SXR) imaging and electron cyclotron emission diagnostics. The frequency of the m/n = 1/1 mode exhibited a feature of chirping down with time, and this chirping rate corresponds to the rate of electron diamagnetic drift frequency change. A twisted pattern (‘Taichi structure in shape’) was reconstructed by SXR tomography of the m/n = 1/1 mode. The perturbations of electron temperature and density caused by m/n = 1/1 are different in size, the latter one being much smaller. The destabilization of m/n = 1/1 was due to the strong central heating combined with electron cyclotron resonance heating and lower hybrid current drive. In the presence of the m/n = 1/1 mode, a negative current was generated on the magnetic axis, which anomalously broadened the core current profile. A m/n = 3/2 tearing mode triggered by m/n = 1/1 mode was also observed. The m/n = 3/2 mode has a smaller frequency than the m/n = 1/1 mode, and carries an m/n = 3/2 island with detectable size. A novel 3D MHD model that separately evolves the plasma density and temperature is applied to the m/n = 3/2 triggered by m/n = 1/1. It is found that a toroidal current density at the q = 1.5 surface, caused by non-axisymmetric density perturbation during the m/n = 1/1 nonlinear growth phase, was generated and hence the destabilization of the m/n = 3/2 tearing mode. Both the modeled electron temperature and density perturbations agree well with experimental observations. In the last section of this paper, the interaction between the m/n = 1/1 mode and fast electrons as well as the active control of this mode are also presented.

Probing the lower ionospheric electron density modulation by the 2019 solar eclipse with VLF phase studies and ion-chemistry model

During a solar eclipse, the temporary blockage of daytime solar illumination resembles a nighttime situation up to a certain degree. This effectively modulates the lower ionosphere by reducing the ionization rate and hence electron–ion density and the VLF signal responds accordingly. This study investigates the lower ionospheric response to the Annular Solar Eclipse of December 26, 2019 (ASE19) by analyzing VLF phase modulation as observed from four different locations in India during the campaign organized by the Indian Centre for Space Physics (ICSP), Kolkata. The eclipse path crossed the four signal paths between NWC (19.8 kHz) transmitter and the receivers from time to time and produced significant deviations in the detected signal amplitudes and phases. We adopt the analysis of the phase delay mechanism to obtain the perturbed electron density fluctuations over the paths and compute changes in VLF reflection heights during the eclipse. The electron density modulation during the eclipse with an in situ theoretical chemical model using the solar obscuration at five different points over all the signal paths are also calculated and compared with the results from VLF. Both the temporal VLF responses at the receiving points and the changes in derived electron densities are found to exactly follow the obscuration profile at the point of maximum obscuration for all the paths. This article, for the first time successfully compares two distinct independent models related to lower ionosphere during a solar eclipse and demonstrates that though we lack the necessary means to directly explore the lower ionospheric dynamics, our theories are more than adequate and roughly reflect the actual scenario.

Perturbation Theory Treatment of Spin–Orbit Coupling. III: Coupled Perturbed Method for Solids

A previously proposed noncanonical coupled-perturbed Kohn-Sham density functional theory (KS-DFT)/Hartree-Fock (HF) treatment for spin-orbit coupling is here generalized to infinite periodic systems. The scalar-relativistic periodic KS-DFT/HF solution, obtained with a relativistic effective core potential, is taken as the zeroth-order approximation. Explicit expressions are given for the total energy through third-order, which satisfy the 2N + 1 rule (i.e., requiring only the first-order perturbed wave function for determining the energy through third-order). Expressions for additional second-order corrections to the perturbed wave function (as well as related one-electron properties) are worked out at the uncoupled-perturbed level of theory. The approach is implemented in the Crystal program and validated with calculations of the total energy, electronic band structure, and density variables of spin-current DFT on the tungsten dichalcogenide hexagonal bilayer series (i.e., WSe2, WTe2, WPo2, WLv2), including 6p and 7p elements as a stress test. The computed properties through second- or third-order match well with those from reference two-component self-consistent field (2c-SCF) calculations. For total energies, E(3) was found to consistently improve the agreement against the 2c-SCF reference values. For electronic band structures, visible differences w.r.t. 2c-SCF remained through second-order in only the single-most difficult case of WLv2. As for density variables of spin-current DFT, the perturbed electron density, being vanishing in first-order, is the most challenging for the perturbation theory approach. The visible differences in the electron densities are, however, largest close to the core region of atoms and smaller in the valence region. Perturbed spin-current densities, on the other hand, are well reproduced in all tested cases.

Wave Perturbations of the Lower and Upper Ionosphere during the 2019 Faxai Tropical Typhoon

In this paper, we studied the response of the lower and upper ionosphere to the passage of TyphoonFaxai 2019 using the regional network of ultralong-wave radio translucence stations in the Far East region ofRussia and measurements of electron density perturbations using the SWARM mission satellites. The presentedexperimental data clearly demonstrate wave perturbations of the amplitude and phase of the ULW signal,as well as the electron density during the active stage of the typhoon. The parameters of wave perturbationscorrespond to atmospheric internal gravity waves. The maximum spectral density of wave perturbations in thelower ionosphere corresponds to 16–20 min. A mechanism for the impact of internal waves on the ionosphere,which is due to polarization fields arising from the wave motion of plasma in the lower part of the F-region, isproposed. These fields projected along the geomagnetic field lines make it possible to interpret the observedvariations in the phase of the ULW signal and variations in the electron density in the upper ionosphere

On charged photons in unmagnetized dusty plasma instabilities

Motivated by the expanding interest in complex plasmas, we discuss the equivalent photon charge in dusty electron-ion plasmas. Particularly, we investigate the dusty plasma response in terms of the electron density perturbation driven by electromagnetic waves. The resulting polarization of this plasma medium caused by the photon ponderomotive force of the electromagnetic radiation pressure gives rise to an effective photon electric charge. We determine the acquired photon charge in terms of the involved characteristic parameters. More precisely, here we derive an explicit expression of the photon charge which is found to depend strongly on the free electron density and the photon frequency. Such a photonic charge is relevant for dealing with the photon–plasma couplings in most plasma mediums, namely of the early Universe.

Statistical Correlation Between DEMETER Satellite Electronic Perturbations and Global Earthquakes With M ≥ 4.8

Upon obtaining a relatively low false discovery rate (FDR) of alarms and a low false negative rate (FNR) of earthquakes, several previous long-term statistical researches concluded that ionospheric perturbations recorded by satellites are statistically related to earthquakes. However, overly large time-space windows for correlating perturbations with earthquakes will also contribute to low FDR and FNR. In this study, a new score - the number of non-randomly successful alarms - is used to quantitatively describe the sensitivity of Electron Density Perturbations (EDPs) recorded by the DEMETER satellite to global earthquakes with <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</i> ≥4.8. Results show that the EDPs are significantly related to global medium-to-strong earthquakes and that optimal parameters for removing EDPs which are non-related to earthquakes and the optimal time-space windows for correlating earthquakes and EDPs are variable in space. Moreover, our results show that the intensity of EDPs makes little contribution to distinguishing the perturbations related to earthquakes with different magnitudes and perturbations non-related to earthquakes, while the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K_p</i> index is effective for improving the Signal/Noise ratio of our model, where Signal/Noise refers to the EDPs related/non-related to earthquakes. Finally, using the optimal time-space windows for correlating EDPs and earthquake, we construct several earthquake prediction models and quantitatively evaluate their power. We find that these EDP-based earthquake predictions are better than the spatially variable Poisson model showing the great potential of predicting earthquakes based on satellite-based Earth observation techniques. However, the spatio-temporal accuracy of these models for predicting earthquakes is not satisfactory, as the alerted time-space volume is big.

Twisted plasma waves driven by twisted ponderomotive force

We present the results of twisted plasma waves driven by twisted ponderomotive force. With the beating of two, co-propagating, Laguerre-Gaussian (LG) orbital angular momentum (OAM) laser pulses with different frequencies and also different twist indices, we can obtain the twisted ponderomotive force. Three-dimensional particle-in-cell simulations are used to demonstrate the twisted plasma waves driven by lasers. The twisted plasma waves have an electron density perturbation with a helical rotating structure. Different from the predictions of the linear fluid theory, the simulation results show a nonlinear rotating current and a static axial magnetic field. Along with the rotating current is the axial OAM carried by particles in the twisted plasma waves. A detailed theoretical analysis of twisted plasma waves is also given.

Mechanism of near-forward scattering driven photon acceleration in the interaction between an intense laser and under-dense plasmas

The mechanism of photon acceleration driven by the near-forward scattering (NFS) in the interaction between an intense laser and under-dense plasmas is studied by particle-in-cell (PIC) simulation. This mechanism utilizes tunneling ionization effect to stimulate electron plasma waves when the intense laser pulse propagates in under-dense plasmas. The electron plasma density is inhomogeneous both in longitudinal and transverse direction. In the longitudinal direction, a steep ionized electron density front is generated by incident laser ionizing the helium gas. Around the ionization front, the incident laser interacts with electron plasma waves, thus generating the first kind of NFS waves. Compared with the frequency of laser, the frequency of NFS wave increases. This is the first characteristic peak in the frequency spectrum. In the transverse direction, the electron plasma waves have different phase velocities, which makes the incident laser pulse undergo NFS process and upshift its frequency. This is the second characteristic peak in the frequency spectrum. Owing to the fact that the electron density inhomogeneity is much larger than the electron density perturbation of electron plasma wave, the scattering model and dispersion relationships, which are based on perturbation theory like stimulated Raman scattering, are no longer applicable to this case. Our further study shows that the incident laser, electron density plasma waves and NFS waves still satisfy the energy conservation and momentum conservation that is, they still satisfy the three-wave coupling relationship of momentum and energy conservation under the condition of heterogeneous density, thus explaining the appearance of two characteristic peaks in the frequency spectrum and their growth in the wave-vector space. This study has significant reference to the spectrum evolution when the intense laser pulse propagates in under-dense plasma.

Seismic Induced Ground Deformation and Ionospheric Perturbations of the 29 July 2021, Mw 8.2 Chignik Earthquake, Alaska

AbstractThe subsurface, surface, and ionospheric characteristics associated with the 29 July 2021 Mw 8.2 Chignik Earthquake are studied in detail using continuous Global Positioning System (cGPS) data over Alaska. The cGPS‐inverted coseismic displacements demonstrate that the slip is distributed along the rupture area northeast of the epicenter with a maximum coseismic slip of ∼3.85 m occurring at a depth of ∼24.25 km. The vertical surface displacement estimated from the coseismic slip exhibits a similar deformation pattern with a maximum uplift of ∼1.0 m over the highly slip area. The ionospheric electron density perturbations associated with the Chignik earthquake were investigated using cGPS‐derived Total Electron Content (TEC) data. Unlike the northeast‐directed coseismic rupture and surface uplift, the ionospheric imprints of this event are more dominant southwest of the epicenter. This study reveals that the Earth's magnetic field and the ionospheric background electron density significantly controlled the TEC perturbation orientation and amplitudes rather than the rupture propagation and coseismic uplift pattern.

Receiver circuit improvement of dual frequency-comb ka-band Doppler backscattering system in the large helical device (LHD).

Doppler-backscattering (DBS) has been used in several fusion plasma devices because it can measure the perpendicular velocity of electron density perturbation v⊥, the radial electric field Er, and the perpendicular wavenumber spectrum S(k⊥) with high wavenumber and spatial resolution. In particular, recently constructed frequency comb DBS systems enable observation of turbulent phenomena at multiple observation points in the radial direction. A dual-comb microwave DBS system has been developed for the large helical device plasma measurement. Since it is desirable to control the gain of each frequency-comb separately, a frequency-comb DBS system was developed with a function to adjust the gain of the scattered signal intensity of each channel separately. A correction processing method was also developed to correct the amplitude ratio and the phase difference between the in-phase and quadrature-phase signals of the scattered signals. As a result, the error in Doppler-shift estimation required to observe vertical velocity and the radial electric field was reduced, which enables more precise measurements.

Excitation of long electrostatic solitary waves in ion beam neutralization process

Unusually long electrostatic solitary waves (ESWs) are discovered in a particle-in-cell simulation study of the process of ion beam neutralization by electron emission from a filament. These ESWs are long because the density perturbation responses to the potential wells created by the ESWs are very small. The density perturbation is small because the trapped (positive) and untrapped (negative) electron density perturbations nearly compensate each other because of a non-Maxwellian electron velocity distribution in the beam.

Polarisabilities of iterated stockholder atoms

Polarisabilities of atoms within molecules can be calculated from molecular electron densities using the density partitioning method known as Iterated Stockholder Atoms (ISA). Non-local polarisation effects are removed by optimising the ISA functional for the perturbed electron density, with the additional constraint that the atomic charges do not change. The resulting atomic polarisabilities are chemically reasonable, tend to become smaller as the atomic charge becomes more positive, and are approximately transferable between atoms in similar chemical environments. The methodology can be extended to calculate local higher-rank polarisabilities and dispersion energy coefficients.

Study of Ionospheric behaviour during the intense geomagnetic storms in 24th solar cycle over different Latitudes and Longitudes

AbstractAn analysis of geomagnetic disturbances and global ionospheric electron density perturbations during the 2015 St. Patrick’s Day geomagnetic storm is presented in this paper. GPS observations from worldwide IGS stations are used and analysed through GPS-TEC analysis application developed by Gopi Seemala to get VTEC profiles. The St. Patrick’s geomagnetic storm covers the interval of 15-23 March 2015, when transient solar eruptions (a prolonged C9-class solar flare and associated CMEs on 15 March) and a strong geomagnetic storm during 16-18 March (Dst dropped to -223 nT) were reported. This geomagnetic storm led to complex effects on the ionosphere. The global maps have been created after analysing VTEC profiles at Low, Mid and High-latitudes over different longitudinal sectors. Major features of the positive and negative ionospheric storm development are observed in Asian, European and American Low, Mid and High-latitudes.