This study reports an event-specific longitudinal asymmetry of ionospheric irregularities during 23-24 April 2023 geomagnetic storm (SYM-H: −233 nT), utilizing multi-instrument observations (ground-based GNSS and magnetometer along with space-borne Swarm and GOLD satellites). The rate of change of total electron content index (ROTI) is used as a proxy for ionospheric irregularities. Irregularities were largely absent over most western longitudes, except over the Western African sector, where they persisted from 22 to 26 April. On 24 April, these were restricted to 90 °–70 °W during post-midnight hours. On the contrary, over eastern longitudes, irregularities were observed on all days except 24 April. Electron density depletions near ∼12 °W and ∼35 °W reached beyond ∼40 °N and 30 °S Glat on 23 April. Persistence of irregularities observed at GNSS stations YKRO, ACRG, and NKLG over the African longitude sector suggests a decoupling from storm-time magnetospheric electric fields, however suggests dominance of local-time control, background electrodynamics, or trans-equatorial winds, which is relatively a rare observation and strengthens the regional resilience of EPB generation mechanisms. By applying a moving average filter to the magnetic H-component, contributions of prompt penetration (DP2) and disturbance dynamo (Ddyn) currents are separated, with peak activity during southward IMF Bz. Simultaneous DP2 across different local time sectors and anti-Sq patterns illustrate the roles of storm time ionospheric currents. There is a clear sector-dependent phase reversal (main vs. recovery phase) within the storm, highlighting the roles of storm-time drivers, and storm phase alone cannot predict irregularities occurrence without longitude context.

Geomagnetically Induced Currents (GIC) are ground-level electric currents driven by rapid changes in the Earth’s magnetic field during geomagnetic disturbances. The impact of GIC is often estimated using the direct current in high voltage AC transformers. Alternatively, the time derivative of the magnetic field (|dB/dt| ) can provide an approximation to the GIC signatures. While most GIC investigations focus on the northern hemisphere, observations in the southern hemisphere, particularly over Antarctica, remain limited. This study examines large amplitude |dB/dt| signatures during the super-intense geomagnetic storm of 10–12 May 2024 using magnetometer data from the Indian stations, complemented by AAL-PIP and the SuperMag network. Applying a threshold of |dB/dt| ≥ 300 nT/min, three |dB/dt| events are identified: one during the storm sudden commencement and two during the recovery phase. The events identified in the recovery phase are associated with large substorms. Further analysis of geomagnetic pulsations indicates that Pi3-Pc5 wave activity contributed to amplified |dB/dt| variations. The contribution of Region 1 Field-Aligned Currents (R1-FAC) is analyzed using AMPERE observations, which show the intensified FAC along with Ps6 pulsations. This study highlights the different sources of large-amplitude |dB/dt| over the less-explored Antarctic region under extreme geomagnetic conditions.

This study investigates the low-latitude ionospheric response to five intense geomagnetic storms using Total Electron Content (TEC), Rate of VTEC Index (ROTI), and S4 index observations from a NavIC receiver observations at an Indian low-latitude station Sangli (Latitude 16.5 degrees N, Longitude 74.3 degrees E). We analyze variations in the Interplanetary Magnetic Field (IMFBz), solar wind parameters (Vsw, Nsw), geomagnetic indices (SYM-H, Dst), and Equatorial Electrojet (EEJ), along with O/N2 data from the Global Ultraviolet Imager (GUVI). Among the selected storms, September 2017 and August 2018 exhibited positive ionospheric storm effects, while April 2023 showed strong negative effects. The February and March 2023 storms demonstrated both positive and negative responses. VTEC variations during the main and recovery phases were influenced by eastward (positive storm) and westward (negative storm) EEJ, along with thermospheric O/N2 changes. CME-driven storms caused abrupt VTEC enhancements, whereas CIR-HSS-driven storms led to prolonged disturbances due to sustained southward IMFBz. Daytime VTEC enhancements in September 2017, August 2018, February, and March 2023 were linked to eastward electric fields or increased O/N2 ratios, while nighttime VTEC depletions in February, March, and April storms resulted from prolonged equatorial electric field suppression. Strong ionospheric irregularities and plasma bubble occurrences were observed, particularly during the 2023 storms with higher ROTI and S4 index values. The extreme EEJ suppression in April 2023 and pre-storm irregularities suggest ionospheric preconditioning. (c) 2025 COSPAR. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

The present investigation is directed to explore the southern polar ionospheric responses to intense/strong space weather events and the corresponding correlations with plasma convection and auroral precipitation. The main phases of six geomagnetic storms occurring in the year 2023 (ascending phase of the present solar cycle) are considered for this study. The ionospheric Total Electron Content (TEC) measurements derived from GPS receivers covering the Antarctic region are used for probing the electron density perturbations during these events. Auroral precipitation maps are shown to understand the locations of the GPS stations with respect to particle precipitation. SuperDARN maps are shown to understand the effects of plasma convection over these locations. Correlation between the enhanced TEC observations with the auroral precipitation (R similar to 0.31) and the plasma convection (R similar to 0.8 8) reveals that the latter is more responsible for causing significant enhancements in the diurnal maximum values of TEC over the Antarctic region in comparison to the former. Therefore, this work shows correlation studies between two physical processes and ionospheric density enhancements over the under-explored south polar region under strong levels of geomagnetic activity during 2023. (c) 2025 COSPAR. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

The day-to-day variability of low latitude ionospheric TEC and F-layer height is influenced by various drivers including electrodynamics, neutral dynamics and wind forcing. A comprehensive knowledge on the relative role of various drivers is essential to characterize the ionospheric behaviour. This study investigates the behaviour of ionospheric F-layer during strong TEC deviations under quiet geomagnetic conditions over Ahmedabad, located near the Equatorial Ionization Anomaly (EIA) crest using ionosonde and GPS-TEC observations during 2015 (high solar activity) and 2017 (low solar activity). Significant enhancements and decrements in daytime F-layer peak electron density (foF2) are observed during quiet-time TEC deviations. The F-layer height parameters show distinct patterns during events of deviations in TEC and foF2. In some events, substantial changes occur in the peak height (hmF2) while the base height (h′F) remains nearly constant, whereas, in other events both h′F and hmF2 vary simultaneously, indicating distinct dynamical responses of the F-layer. Signatures with dominant periods between 2 and 5 days are identified in day-to-day foF2 variations, suggesting the possible role of modulation by planetary-scale waves through vertical coupling between the lower atmosphere and the ionosphere–thermosphere system. Day-to-day variations in the zonal electric field strength as seen in EEJ coincide with the strong deviations in foF2 during some events, while several events show no significant correspondence with the electric field behaviour. The electron density distribution of the F-region shows distinct altitude-dependent response depending on whether the day-to-day variability of foF2 and TEC are associated/not-associated with corresponding electric-field variations. The results from this study highlight the complex interplay between electrodynamic and neutral dynamic processes governing quiet-time F-layer variability and altitude-dependent electron density distribution, which provide new insights on the governing factors for the day-to-day ionospheric variability over low latitudes.

Using data from a cluster of ground-based global navigation satellite system, we observed spatially extended enhanced ROTI over the European longitudes during a weak geomagnetic storm (Dst -50 nT) on 4 November 2023. The enhanced ROTI is extended over an extensive geographical latitudinal range of 46 degrees N. Further analysis using other simultaneous ground-based and satellite measurements reveals that the ROTI enhancement is caused by the super plasma bubble (SPB). For instance, a strong range spread and depletion in total electron content (TEC) were observed in the enhanced ROTI regions. Following this, depletion in TEC and OI135.6 nm irradiance was also observed along similar longitudes and latitudes on the African continent. Simultaneous Swarm-A and C electron density showed plasma depletion between 15 degrees S and 31 degrees N at 10 degrees E, which agrees with the enhanced ROTI data as well. To explore the cause of this enhanced ROTI, the prompt penetration equatorial electric field model (PPEEFM) PPEEFM and magnetometer data have been analyzed. We found a sharp decrease in the geomagnetic field during the evening hours, which suggests the ingression of the prompt penetration electric field (PPEF). The PPEF arrival time coincides with the post-sunset pre-reversal enhancement; consequently, an SPB was generated. This study provides observational evidence of SPB in weak geomagnetic conditions, shedding light on the causative mechanism.

A unique two-dimensional gridded geomagnetic map of India is constructed using the geomagnetic field observations from 11 observatories of India, operated by the Indian Institute of Geomagnetism. In order to create the spatial grid, 11 spatial techniques are compared with observed magnetic field during 2011–2020. Out of the 11 known techniques of spatial interpolation, the Modified Shepard’s Method is selected as the best suitable method for interpolation. The spatial gird provides the hourly values of absolute and variations in horizontal (H) and vertical (Z) magnetic field over India. The spatial grid can be applied to higher temporal resolution of data sets as well. This map can be used to get the regional changes in the magnetic field during quiet and disturbed conditions. A user-friendly MATLAB based GUI is created for obtaining the spatial grid.

It is known that the ionospheric Total Electron Content (TEC) variations estimated by the IRI model show large differences from observed values over the low latitudes. While studies on the topside ionospheric contributions to the errors in the modeled TEC by the IRI are under active consideration, there have been no studies on the role of the contribution of the bottom‐side ionosphere. As ionosondes provide the true information on the bottom‐side TEC, in this work a comparative study has been carried out in discerning the role of various parameters that go into the estimates of bottom‐side density profiles and electron content in the IRI model (TECb_iri). The digisonde measurements over a low latitude location, Ahmedabad, India are used to estimate the bottom‐side electron content (TECb_digi) during 2015 and 2018. It is found that the TECb_iri is overestimated during day time irrespective of the season and solar activity. The maximum differences in TECb_digi are noted during equinoctial months and high solar activity period. Among the F‐layer peak and profile parameters, the model differences in the bottom‐side thickness ( B0 ) are found to be consistent with the differences in the TECb_iri. The agreements and discrepancies between TECb_iri and TECb_digi, under the influence of complex electrodynamic processes and solar flux are discussed. This study provides crucial information required to delineate the contributions of different empirical parameters in the IRI to address the discrepancies that exist in the bottom‐side ionospheric modeling over low latitudes.

This work shows an anomalously enhanced response of the low-latitude ionosphere over the Indian sector under weak geomagnetic conditions (October 31, 2021) in comparison to a stronger event (November 04, 2021) under the influence of an Interplanetary Coronal Mass Ejection (ICME)-driven Magnetic Cloud (MC)-like and sheath regions respectively. The investigation is based on measurements of the Total Electron Content (TEC) from Ahmedabad (23.06°N, 72.54°E, geographic; dip angle: 35.20°), a location near the northern crest of the Equatorial Ionization Anomaly (EIA) over the Indian region. During the weaker event, the observed TEC from the Geostationary Earth Orbit (GEO) satellites of Navigation with Indian Constellation (NavIC), showed diurnal maximum enhancements of about 20 TECU over quiet-time variations, as compared to the stronger event where no such enhancements are present. It is shown that storm intensity (SYM-H) or magnitude of the southward Interplanetary Magnetic Field (IMF) alone is unable to determine the ionospheric impacts of this space weather event. However, it is the non-fluctuating southward IMF and the corresponding penetration electric fields, for a sufficient interval of time, in tandem with the poleward neutral wind variations, that determines the strengthening of low-latitude electrodynamics of this anomalous event of October 31, 2021. Therefore, the present investigation highlights a case for further investigations of the important roles played by non-fluctuating penetration electric fields in determining a higher response of the low-latitude ionosphere even if the geomagnetic storm intensities are significantly low.

The Himalayas are a region of geomagnetic importance, as they impact the geomagnetic field of Earth and space weather, as it is one of the largest mountain belts in the world. Due to its huge mass, it may influence the dynamics of the Earth’s core, the primary source of the geomagnetic field. In Indian longitudes, the mean location of the solar quiet (Sq) focus lies in latitudes closer to the Hanle region. Therefore, monitoring the magnetic field in the Hanle region is important. Ideally, a zero magnetic gradient or low magnetic gradient of the order of a few nT/m or less is preferred; this low gradient helps reduce the effects of local magnetic variations. Hence, to establish a continuous geomagnetic observation setup, a magnetic survey was conducted at Hanle, Ladakh, to identify the location of the low magnetic gradient. From the magnetic survey, the eastern part of the selected hillock was identified that has the least magnetic gradient. After checking other logistics, the chosen site is suitable for setting magnetic field observations. The proposed magnetic observatory at Hanle will be useful for studies related to unusual space weather phenomena, such as the citing of Auroras (of 22–23 April 2023 and 10–11 May 2024) in the Ladakh region, geomagnetic field monitoring in low-mid transitional regions, or magnetic exploration.

Ionospheric delay is of concern for trans-ionospheric radio communication, especially for the navigation systems relying on these satellite signals. Most of the ionospheric delays are estimated to a degree of first-order using dual frequency global navigation satellite system (GNSS) receivers except during irregularities and equatorial plasma bubbles. The plasma bubbles are observed as a decrease or reduction in total electron content (TEC) as a result of large-scale irregularities that are generated at the equatorial ionosphere. These plasma bubbles can be detected from TEC values visually or by using mathematical algorithms. The mathematical algorithms may have limitations based on assumptions made for the current dataset. Therefore, various machine learning (ML) techniques were tried by training them with selected TEC depletions that are verified for accuracy. From this study, the Random Forest Method (RFM) has performed well compared to other ML methods. The RFM is trained to use for the detection of TEC depletions from the Indian low-latitude region. The training accuracy obtained is 97.6%, with a minimum classification error of 0.023%. The result obtained from the confusion matrix ascertained that the proportion of positively classified cases that are truly positive that is the positive predictive value (PPV) is 96.8%. These statistical results are validated after plotting the observed TEC depletion patch obtained from the ML method. There are cases in which depletions detected by the ML method are appreciable over the mathematical algorithm. The ML technique once trained will not have inherent limitations, as there are no assumptions or threshold values needed to set as required by most of the mathematical algorithms. Thus, the results are encouraging and have scope for further improvement and advancement.

The ionosphere shows regular changes such as daily, 27 days, seasonal, semi-annual, annual, and 11 years. These changes can be modeled and their effects largely determined. However, in addition to regular changes, irregular changes occur in the ionosphere due to space weather conditions, natural disasters, and human-induced irregularities. GNSS is one of the instruments along with many others that can give a piece of information on the ionospheric state. Various indices/parameters are used to determine the effect of space weather conditions. The well-known ones are solar activity indices, geomagnetic storm indices, magnetic field components, proton density, and proton flux parameters. It is important to take all of these indices into consideration when investigating the source of the anomaly. Considering only some of them may lead to incorrect inferences about the source of possible anomalies. To carry out comprehensive research in this field, it is necessary to analyze a very large data set. This indicates the requirement for an automatic system. With the Global and Regional Ionosphere Monitoring System (GRIMS) designed within the scope of this study, the ionosphere can be monitored globally and regionally. The GRIMS is online at https://www.online-grims.com/ . By using Global ionospheric maps and GNSS receiver data, global, regional, and station-specific anomalies can be detected regularly through methods such as HDI (Highest Density Interval) and ARIMA (Autoregressive Integrated Moving Average). GRIMS gathers space weather-related parameters from ionospheric data centers to help users interpret the situation, and it allows users to download the results and request data for specific days. The details of the experimental results and output products of the system designed during the geomagnetic active days of March 17, 18, 2015 are given in this paper. Moreover, geomagnetic active days that occurred between 2000 and 2023 are given in the GRIMS.

We investigated the ionosphere response to the two severe geomagnetic storms in the ascending phase of solar cycle 25 which occurred during the 23-24 March 2023 (SYM-Hmin = −169 nT) and 23-24 April 2023 (SYM-Hmin = −233 nT) using a latitudinally aligned dense network of Global Navigation Satellite System (GNSS) receivers, magnetometers, and digisonde along the Indian longitude sector. The significant variations in TEC during the storm’s main and recovery phases are mainly linked to the influence of westward Disturbance Dynamo Electric Fields (DDEFs). During the initial phase of the March 23-24 geomagnetic storm, no changes in daytime TEC were observed, despite the storm occurring at noon time with a southward IMF Bz due to the influence of electron density in the top side ionosphere. Furthermore, both pre-reversal enhancement (PRE) and ionosphere irregularities are suppressed within two hours of their onset during the main phase of the March 23-24 storm, owing to the westward transition of zonal electric fields from an eastward direction. During the recovery phase of both storms, a daytime positive storm effect is observed over the dip equatorial region, while the beyond equatorial ionization anomaly (EIA) and mid-latitude regions perceived a negative ionospheric storm effect. This phenomenon is attributed to the influence of the dominant westward DDEFs during the period. Moreover, these DDEFs effectively inhibited the equinoctial manifestation of PRE effects and post-sunset ionospheric irregularities during the recovery phase of both storms. These findings are further confirmed with supporting information from TEC recorded by Swarm satellites, model-derived ionospheric electric fields, and thermospheric O/N2. The results from this study may advance the understanding of ionospheric response to severe geomagnetic storms under the prevailing westward DDEFs during the dayside recovery phase, complementing the global efforts for more reliable space weather modeling and prediction services.

We report an unusual event on absence of high frequency (HF) echoes in ionosonde observations from the ionospheric F2 region during the geomagnetic storm of 23-25 April 2023. This event was observed in both southern and northern hemispheres over two stations, Grahamstown (33.3 degrees S, 26.5 degrees E), South Africa and Pruhonice (50.0 degrees N, 14.6 degrees E), Czech Republic. Significant O/N2 depletion over the stations was observed by TIMED/GUVI, indicating a strong negative ionospheric storm. This is unique since absence of echoes in ionosonde measurements is usually due to strong radio absorption in the ionosphere associated with solar flares. However, there was no flare activity during the periods of "absent" F2 HF echoes. On the other hand, the ionosonde detected echoes from E-layer. TIEGCM simulation reproduced TIMED/GUVI O/N2 depletion and showed that NmE was larger than NmF2 on dayside over Pruhonice. TIMED/GUVI O/N2 also showed a clear spatial gradient in the O/N2 depleted regions, suggesting F-region ionosphere was tilted. By estimating the critical frequency of the F2 layer using GNSS observations, we have shown that it wasn't possible for the ionospheric electron density to reach depletion levels prohibiting reflection of HF echoes from ionosondes. We suggest that this phenomena may have been caused by either (a) maximum electron density of E layer exceeding that of F2 layer and/or (b) ionospheric tilting which made the signals to be reflected far away from the ionosonde locations. Solar eruptions such as coronal mass ejections (CMEs) can lead to geomagnetic storms which cause temporal disturbances in the Earth's thermospheric temperature and composition as well as profound changes in ionospheric electron densities. One of the consequences for this phenomena is the negative ionospheric storm where ionospheric electron density is reduced from its "regular" background values. In this study, we report on the temporal absence of high frequency (HF) radio echoes from the ionospheric F2 layer in ionosonde measurements during the geomagnetic storm of 23-25 April 2023. Thermospheric neutral composition observations and simulation suggested that the absence of HF echoes was due to the intense negative ionospheric storm. HF signals were not reflected back to the ionosonde location during part of the main phase possibly due to ionospheric tilting Maximum electron density of the F2 layer derived from GNSS observations correctly identify the negative ionospheric storm effect The auroral oval moved closer to mid latitudes during the storm main phase

The variation of correlation between ROTI and S4 index is examined by using GPS L1 and L5 signals over an Indian low latitude station, Waltair (17.73° N, 83.37° E) during the period from 2015 to 2017. The effect of geomagnetic storms on the correlation between ROTI and S4 index is the main focus of the present study. The influence of satellite elevation angle and signal frequency on the correlation between ROTI and S4 index is also investigated during different seasons and geomagnetic conditions. The correlation is found to vary between 0.28 and 0.63 for elevation angles above 30⁰ and between 0.56 and 0.87 for the elevation angles above 50⁰. The correlation coefficient values are decreasing with solar activity from 2015 to 2017 during quiet and disturbed geomagnetic periods. From the analysis on the seasonal correlation between ROTI and S4 index, it is found that solar activity dependent seasonal correlation is observed for both GPS L1 and L5 signals over lower elevation angle 30⁰. The correlation between ROTI and S4 index is increasing over higher elevation angles and for lower signal frequency.

Forecasting Indian Summer Monsoon Rainfall (ISMR) is a formidable task due to its intricate variability. This study harnesses the power of machine learning (ML) to decipher the chaotic trajectory within ISMR, drawing inspiration from ML's success in predicting analogous systems. By utilizing ERA-interim data, the method dissects ISMR's chaotic nature through correlation dimension-based techniques. Employing the Lorenz-96 model on daily rainfall data, trained with an Echo State Network (ESN), the technique discerns patterns within a span of 1 model time slightly trailing its performance in other systems. This discrepancy could stem from the intricacies of observational data and the training process involving 500 initial conditions. Notably, this method achieves accuracy in slightly over 50

Abstract The Equatorial Electrojet (EEJ) is one of the important near‐earth space weather phenomena which exhibits significant diurnal, seasonal and solar activity variations. This paper investigates the EEJ variations at diurnal, seasonal and solar cycle time scales from the Indian sector and portrays a new empirical EEJ field model developed using the observations spanning over nearly two solar cycles. The Method of Naturally Orthogonal Components (MNOC), also known as Principal Component Analysis (PCA), was employed to extract the dominant patterns of principal diurnal, semi‐diurnal, and ter‐diurnal components contributing to the EEJ variation. The amplitudes of these diurnal, semi‐diurnal, and ter‐diurnal components in EEJ are found to vary significantly with the season and solar activity. The seasonal and solar activity dependencies of these principal components are modeled using suitable bimodal distribution functions. Finally, the empirical model for EEJ field was built by combining the principal components with their corresponding modeled amplitudes. This model accurately reproduces the diurnal, seasonal and solar activity variations of EEJ. The modeled monthly mean variations of EEJ field at ground exhibit excellent correlation of 0.96 with the observations with the root mean square error <5 nT. It also successfully captures the seasonal and solar activity variations of Counter Electrojet (CEJ). Finally, this model named “Indian Equatorial Electrojet (IEEJ) Model” is made publicly available for interested scientific users (https://iigm.res.in/system/files/IEEJ_model.html).

Space weather variations can significantly affect ionospheric electron density, which can, in turn, adversely affect various navigational and communication technologies. One such phenomenon is the prompt penetration electric field. The convective electric field from a magnetospheric origin penetrates the lower ionosphere during a geomagnetic storm. The electric field penetrating the ionosphere can challenge space-based technologies. Thus, understanding the convectional electric field from higher latitudes to the low-latitudinal region during geomagnetic disturbance is critical. The ionosphere over the Indian region consists of equatorial and low latitude dynamics, such as equatorial ionization anomaly, that are highly dynamic even during the quiet days. Therefore, understanding the effects of prompt penetration electric field observed in the Equatorial Electrojet is of utmost importance over the Indian region. In the current study, two geomagnetic storms, the St. Patrick's Day storm of 17th March 2015 and another low intense storm of 8th June 2014, were chosen to understand the effects of PPEF over equatorial ionization anomaly. The ionospheric density was enhanced during the relatively less intense geomagnetic storm compared to the St. Patrick's Day storm. In these two events, large-scale ionospheric irregularities were observed from ROTI values during the local daytime hours, but no ionospheric scintillation was detected (S4 index).

During 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 (<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.

Simultaneous observations of the atmospheric electric potential gradient (PG) at Bharati and Maitri stations were studied from 2014 to 2016. A new regional diurnal pattern of fair-weather PG for the coastal Antarctic region, perhaps the ubiquitous characteristics of the PG for the coastal Antarctic region, has been identified. This pattern has a significant broad minimum around noon hours. It is around this time the wind speed is also maximum. The PG data of past years of Syowa, Vostok, and Carnegie Cruise were also used in this study. The surface wind distorts the fair-weather diurnal pattern of PG over Bharati more intensely than at Maitri. The katabatic wind effect on the PG at Bharati appears to be more intense than at Maitri. The topography and katabatic winds associated with the Lambert glacier could be the reason. The observation of Bipolar Air Ion Concentration (BAIC) suggests that the wind speed significantly affects the concentration by accumulation and dispersion. The concentration is maximum when the wind speed is minimum. As the air ion concentration controls the conductivity, the PG is expected to be minimum during these hours to produce an anomalous diurnal pattern in the PG at Bharati. Data quality is improved by measuring the PG with a field monitor at the surface level instead of at an elevated position. This study provides new hope in pursuing globally representative data of the PG for further investigations on the global thunderstorm activity and the solar-terrestrial weather relationship.