Effects Of Geomagnetic Storms Research Articles

Seismo ionospheric anomalies in Turkey associated with Mw ≥ 6.0 earthquakes detected by GPS stations and GIM TEC

Earthquake (EQ) anomalies in the form of enhancement and depletion in ionospheric Total Electron Content (TEC) from Global Positioning System (GPS) may considerably alarm about short and long term precursors of the impending main shock. In this paper, TEC anomalies are investigated from permanent GPS ground-stations in Turkey associated to Mw ≥ 6.0 EQs occurred in 2011–2012. Temporal and spatial analyses of TEC at 2 h sampling have shown significant evidences about EQ induced ionospheric anomalies during 10–14 h of UT (Universal Time) within 5 days before Mw 6.0 Greece, and Mw 7.1, Turkish EQ. Spatial analyses have manifested arrival of TEC anomalies at UT = 10 h to epicenter of both EQs, which linger above epicenter during UT = 12–14 h and left seismogenic zone after UT = 14 h before every EQ during Kp < 3 and Dst = 0 nT. Meanwhile, a geomagnetic storm (Dst < -100 nT) induce perturbation two days after the Mw 7.1 Turkish EQ, showing no relation with epicenter during spatial analysis. It also shows that TEC can be useful to distinguish geomagnetic storm variations to successfully detect EQ precursors. These anomalies during quiet storm (Kp < 3; Dst = 0 nT) conditions may be effective to link the lithosphere and ionosphere in severe seismic zones to detect EQ precursors before future EQs. Interpretation of TEC anomalies and it enhancements over EQ epicenters during UT = 12–14 h for both EQs have shown that EQs anomalies only occurred in particular time. Whereas, geomagnetic storm effect occurred during whole abnormal day over the Earth.

Global Simulation of Electron Cyclotron Harmonic Wave Instability in a Storm‐Time Magnetosphere

AbstractElectron cyclotron harmonic (ECH) waves are electrostatic emissions between the ECHs and play a dominant role for precipitating energetic electrons in the magnetotail. Statistically, the ECH wave intensity is stronger at nightside and dawnside than at dayside and duskside. In this study, we, for the first time, simulate the global ECH wave evolution during a geomagnetic storm event using Ring current Atmosphere interactions Model with Self‐Consistent Magnetic field (RAM‐SCB) combined with a linear growth rate solver. We find that the simulation results are generally consistent with the statistical and real‐time observations. The ECH wave instability is much stronger at nightside and dawnside, compared to the instability at dayside and duskside. Before a geomagnetic storm (quiet time), the unstable regions of the ECH waves lie beyond with a weak instability level. During the main phase of a geomagnetic storm, the unstable regions can extend to a lower altitude ( ) with a strong instability level. During the recovery phase, the unstable regions return to . We also find that the inner boundary of unstable ECH wave regions is coincident with the plasmapause location during the whole geomagnetic storm event.

Characterization of ionospheric total electron content data using wavelet-based multifractal formalism

Abstract Understanding of the spatio-temporal behaviour of nonlinear geophysical signals, such as ionospheric total electron content (TEC) by multifractal analysis brings out the chaotic and intermittent nature of the signal under consideration. Wavelet-based multifractal analysis was performed on TEC data and the horizontal component of the Earth’s magnetic field (henceforth referred to as H-component) data recorded during geomagnetic storm events at a few sites in equatorial, mid-latitude and high latitude regions (30oS to 80oN), confined to a narrow longitude band ( 35 o W − 80 o W ) (geographic coordinates) during the solar minimum (2008) and solar maximum (2014) years. The study was done using the magnitude cumulant analysis of the wavelet transform. The advantage of this technique, over the well known wavelet transform modulus maxima (WTMM) method in studying the multifractal behaviour of nonlinear signals is explained. Results show that during the major geomagnetic storm events (Dst. Index ≤ − 50 nT) both TEC and the H-component data exhibit strong multifractal behavior and that the degree of multifractality (representative of the width of the multifractal spectrum) for the H-component data is more than that of TEC for all latitudes regardless of solar conditions. A nonlinear P-model, representative of multiplicative cascades for the above data sets, also supports the above observation. It has been observed that these observations hold good when multifractal behaviour of TEC data, with and without its dominant diurnal component, is compared with that of H-component data. A statistical hypothesis testing of the above results obtained using bootstrapping technique also establishes the significance level of the multifractal behaviour of the data.

Statistical study of geomagnetic storm effects on the occurrence of ionospheric irregularities over equatorial/low-latitude region of Africa from 2001 to 2017

The effect of Coronal Mass Ejection (CME) and Corotating Interaction Region (CIR)-driven storms on the occurrence of ionospheric irregularities (OIIs) over the African equatorial and low-latitude region are studied statistically for the first time. In addition to the CME and CIRs’ catalogs, we have used the disturbance storm time (Dst) ≤ -30 nT and Kp ≥ 3 to identify the storm periods. The study was based on Global Navigation Satellite System (GNSS) total electron content (TEC) observation from three stations (nklg: 8.05°S, 81.05°E; mbar: 10.22°S, 102.36°E; and nazr: 0.25°S, 111.01°E, Geomagnetic) during 2001–2017. Based on the GNSS observations, the rate of change of total electron indices (ROTIROTI and ROTIave) have been used to observe the presence/absence of ionospheric irregularities. To examine the effect of the storms on the OIIs, ratio of ROTIave of the selected storm period to the quiet monthly mean of ROTIave, ROTIratio=ROTIobs/ROTI‾quiet, was applied. Based on our analysis, ROTIratio≥3.2, ROTIratio≤0.16 and 0.16<ROTIratio<3.2 were identified as threshold values indicating the enhancement (EN), suppression (SP), and no significant (NE) effect of the storms on the OIIs, respectively. Our results revealed that the SP in the OII during CME-and CIR-driven storms are more prevalent than the EN. During both CIR-and CME-driven storms, the percentage occurrence rate in EN observed over nklg was greater than mbar and nazr. Most of the SP effect of the storms, on the other hand, was predominantly observed over nazr and mbar stations. The occurrence rate of EN, SP and NE effect of both CME-and CIR-driven storms show dependence on the local time at which large decrease in Dst occurs. We also found that SP effect of both CIR-and CME-driven storm show a positive and linear correlation with sunspot number (SSN). While the EN effect of CIR-driven storm show a negative and linear relation with SSN, CME-driven storm effects show weak relation. The polarity and amplitude of different sources of disturbance electric field observed in the evening hours could play a dominant role in affecting the OIIs. The difference in the seasonal variation in the occurrence rate of EN, SP and NE effect of the storms observed over different stations were also discussed.

First Synoptic Observations of Geomagnetic Storm Effects on the Global‐Scale OI 135.6‐nm Dayglow in the Thermosphere by the GOLD Mission

AbstractThe Global‐scale Observations of the Limb and Disk (GOLD) mission provides, for the first time, a synoptic view of the thermospheric response to a moderate geomagnetic storm at a 30‐min cadence. The observations showed that the OI 135.6‐nm emission substantially decreased at middle and high latitudes, but it increased at low latitudes. The depletion pattern between 4 and 6 November 2018 was likely due to the strong upwelling of the high‐latitude thermosphere. The deepest depletion in brightness that occurred near local noon was of ~300–400 R (~35% of the quiet time background level) and displayed a striking westward movement. First‐principles modeling reasonably reproduced the overall morphology of brightness response to the geomagnetic storm despite the depletion magnitude in brightness being underestimated. The postprocessing of the simulation results revealed that the westward movement of the deepest depletion was attributable to the horizontal wind changes driven by the geomagnetic storm.

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.

Effect of moderate geomagnetic storms on equatorial plasma bubbles over eastern Africa in the year 2012: Evolution and electrodynamics

Equatorial plasma bubbles (EPBs) are common features of the equatorial and low-latitude ionosphere and are known to cause radio wave scintillation which leads to the degradation of communication and navigation systems. Although these structures have been studied for decades, a full understanding of their evolution and dynamics remains important for space weather mitigation purposes. In this study, we present cases of EPBs occurrences around April and July 2012 geomagnetic storm periods over the African equatorial sector. The EPBs were observed from the Communications/Navigation Outage Forecasting System (C/NOFS) and generally correlated well to the ionospheric irregularities observed from the Global Positioning System total electron content (GPS-TEC) measurements (rate of TEC change, ROT). This study revealed that the evolution of the EPBs during moderate storms is controlled by the strength of the daytime equatorial electrojet (EEJ) currents regardless of the strength of the equatorial ionization anomaly (EIA), the latter is observed during the July storm case in particular. These effects were more evident during the main and part of the early recovery phases of the geomagnetic storm days considered. However, the evening hours TEC gradients between regions of the magnetic equator and ionization crests also played roles in the existence of ionospheric irregularities.

A Parallel Solution for the Resilient Operation of Power Systems in Geomagnetic Storms

Optimal operation strategies are essential for maintaining a secure, economic, and resilient operation of power systems in dealing with geomagnetic storms. However, practical efforts for attaining such optimal operations are facing significant modeling and solution challenges that stem from the computational complexity of the geomagnetic disturbance (GMD) mitigation problem. To overcome these challenges, this paper proposes a parallel solution approach to improve the computational efficiency. In this approach, the mixed-integer nonlinear programming (MINLP) problem of mitigating geomagnetic disturbance is split into a nonlinear AC optimal power flow subproblem (ACOPF) and a mixed-integer linear DC geomagnetically-induced current (GIC-DC) mitigation subproblem. The solution mitigates the negative effects of geomagnetic storms by introducing transformer neutral and transmission line series GIC blocking devices, transmission switching, and a host of other operation planning schemes which can enhance the power system resilience. Multiple cases on the 6-bus, 18-bus and 150-bus power systems are studied to show the effectiveness and efficiency of the proposed parallel modeling and solution approach. The studied cases also show that the proposed parallel solution approach offers a promising performance which is based on the applications of augmented Lagrangian relaxation and auxiliary problem principle methods.

Effect of geomagnetic storms on VLF waves at low latitudes based on the analysis of whistlers and VLF emissions observed at Indian ground stations: A Review

Effect of geomagnetic storms on VLF waves at low latitudes based on the analysis of whistlers and VLF emissions observed at Indian ground stations: A Review

Geomagnetic storms and their impacts on Ethiopian power grid

In present work we analysed eight geomagnetic storm events in 2015/2016 and studied the possible influence of these events on Ethiopian power grids. The results showed that the majority of the forced power outages occurred in the period of the main phase of events and the recovery period of the geomagnetic storms. The geomagnetic storms are characterised by different indices and parameters such as the disturbance storm time (Dst) values, coronal mass ejection (CME) speed, solar wind speed (V sw) and interplanetary magnetic field (IMF-Bz) on the selected dates. In most cases the observed geomagnetic storms were produced by the CME-driven storms as they show a storm sudden commencement (SSCs) before the main storms, and also have the short recovery periods. The sudden jumps of the solar wind velocities and IMF-Bz are also consistent with occurrence of the CMEs. Moreover, this effect can be traced in changes of Earth magnetic field during geomagnetic storm and quiet days. The observed CME-driven storms can produce highly variable magnetic fields on the transformers and provide forced outages, however the studied outages have not been recognised as those one driven by a geomagnetic storm.

Contaminated Effect of Geomagnetic Storms on Pre-Seismic Atmospheric and Ionospheric Anomalies during Imphal Earthquake

Study of seismo-ionospheric coupling mechanism demands the quiet geomagnetic condition to eliminate any kind of contamination in the lower atmospheric and ionospheric parameters. In this manuscript, we present the effect of back to back two geomagnetic storms before a strong earthquake happened in Imphal, India on January 4, 2016 (M = 6.7). We studied the lower ionospheric irregularities for the duration of 31 days by computing the nighttime fluctuations in Very Low Frequency (VLF) radio signal received transmitter JJI (22.2 kHz) in Japan at Ionospheric and Earthquake Research Centre & Optical Observatory (IERCOO), Sitapur, India. We also studied the presence of Atmospheric Gravity Wave (AGW) in nighttime VLF signal in lower ionospheric heights and the same computed that from SABER/TIMED satellite. Two geomagnetic storms occurred on December 21, and 31, 2015. By the conventional analysis, we found that there is a significant decrease in nighttime trend and an increase in nighttime fluctuations around 15 days before the earthquake and just on the first storm and thus the pre-seismic effects on VLF signal gets contaminated due to the presence of storms. The wave-like structure in VLF fluctuations shows significant increase in intensity by using Fourier and Wavelet analysis before the earthquake. By analysis of SABER data, we found significant enhancement in AGW around 10 days before the earthquake. As the wavelike structures are coming from neutral acoustics reasons from pressure or temperature variations, this paper exhibits a significant example of contamination in ionospheric parameters due to geomagnetic storm where the acoustics parameters remain un-contaminated.

The First Intense Geomagnetic Storm Event Recorded by the China Seismo‐Electromagnetic Satellite

AbstractOn 25 August 2018, the China Seismo‐Electromagnetic Satellite (CSES) encountered the first intense geomagnetic storm event since its launch on 2 February 2018. The main purpose of this work is to check in‐flight performance of the assembled payloads onboard CSES, as well as to investigate the ionosphere perturbations induced by this geomagnetic storm. The study shows that all investigated parameters simultaneously respond to the different phases of the geomagnetic storm, verifying the measuring capabilities of the assembled payloads onboard CSES. Specifically, the magnetic field obtained from the high‐precision magnetometer fits well with that obtained by the Swarm satellite, clearly demonstrating the development phase of the storm; joint analysis using the Langmuir probe, plasma analyzer, electric field detector, and GNSS occultation receiver data demonstrate that this is a positive storm event and that electric field penetration is the possible mechanism for the disturbance in the ionosphere. During this storm event, some significant ELF/VLF waves are also excited and there is enhancement of the energetic electron flux (of energy &lt;1 MeV). These main features are consistent with results from previous works, indicating the excellent performance of the search coil magnetometer and high‐energy particle detector.

The Effect of Geomagnetic Storms on foF2 Values over Low Latitude Ionosonde Station

In this reseach, the changes in the low latitude critical frequencies (foF2) was investigated during the geomagnetically active hours (geomagnetic storms). The critical frequency (foF2) data obtained for 1991 over Manila that is low latitude ionosonde station and the planetary geomagnetic indices (Kp) were used. The superposed epoch analysis was used as a statistical method to investigate the change in the critical frequencies during geomagnetically active hours. The analyzes were conducted separately for the night hours, day hours and all hours of 1991 and they were compared with each other. The results from this research show that the highest change (increase or decrease) in foF2 values during geomagnetically active hours occurs at the event time (zero time) and the local time (day or night) has a significant impact on this change of the foF2 values. The foF2 values increase at local day hours, while the foF2 values decrease at local night hours.

Solar Variation and Super Geomagnetic Storm Event during March 10-31, 2015

CMEs and solar flares are important solar ejections which are the cause of storm in Heliosphere. These ejections are producing a change in Earth magnetic field. In this paper we have studied heliospheric disturbance of solar cycle 24 during period from 10 March to 31 March 2015. We observed that a huge explosion of magnetic field and plasma from the Sun’s corona on 15 March 2015 and associated solar flares have disturbed space weather towards earth causes strongest geomagnetic storm on 17 March 2015. We found that Dst value reached to its minimum is -223 nT and a FDs during the period on 17 March 2015.

An investigation on time dependency of K index-based geomagnetic storm conditions observed over different locations of North America

Today, the scientists and researchers from almost every corner of the world are well aware of the adverse effects of geomagnetic storms on our highly expensive electrical and electromagnetic systems such as power grid transmission, satellite communication, RF communication systems, etc. The severe damaging effects of these storms on human health and on other inhabitants of the biosphere are also not unknown. A survey of literature on space science reveals that location or space dependency of these geomagnetic storms has already been established. Now the question may arise—Are geomagnetic storms time-dependent? To answer this question, a laborious exercise has been performed. K-index data obtained from the US Department of Commerce, NOAA, Space Weather Prediction Center, for the year, started from 1994 to 2014 (21 years) over three different locations namely Fredericksburg, College, and Estimated Planetary, are analyzed statistically for the eight different time periods namely 00:00–03:00, 03:00–06:00, 06:00–09:00, 09:00–12:00, 12:00–15:00, 15:00–18:00, 18:00–21:00, 21:00–24:00 hours respectively. Results thus obtained have concluded that apart from space or location dependency the geomagnetic storms are time-dependent also.

Delayed consequences of the influence of simulated geomagnetic storms on roach Rutilus rutilus embryos.

This study presents data collected over a 3 year period on the effects of simulated geomagnetic storms (SGMS) on Eurasian roach Rutilus rutilus embryos. Effects were studied during different stages of early development. Rutilis rutilus were raised in ponds for 4 months after exposure to SGMS. The mass, standard length and morphological characteristics of under-yearlings exposed as embryos were recorded. A decrease in length-mass indices in under-yearlings was noted after they had been exposed to SGMS during the first 2 days or during the third and fourth days of early development. Near the time point of 48 h post fertilisation, either no effect or an increased size was observed. In addition, exposure to SGMS led to a redistribution of the vertebral number between the sections of the vertebral column as well as changes in the number of seismosensory system openings in the mandibular and praeoperculum bones of under-yearlings. Observed effects are similar to previously published data on the influence of anthropogenic magnetic fields on roach, namely changes in linear-mass indices, number of vertebrae and number of seismosensory system openings in the mandibular bones of under-yearlings exposed as embryos. Possible mechanisms of magnetic influence on early development of fish are discussed.

Storm-Time Behaviour of Meso-Scale Field-Aligned Currents: Case Study with Three Geomagnetic Storm Events

Challenging Minisatellite Payload (CHAMP) satellite magnetic data are used to investigate the latitudinal variation of the storm-time meso-scale field-aligned currents by defining a new metric called the FAC range. Three major geomagnetic storm events are considered. Alongside SymH, the possible contributions from solar wind dynamic pressure and interplanetary magnetic field (IMF) BZ are also investigated. The results show that the new metric predicts the latitudinal variation of FACs better than previous studies. As expected, the equatorward expansion and poleward retreat are observed during the storm main phase and recovery phase respectively. The equatorward shift is prominent on the northern duskside, at ~58° coinciding with the minimum SymH and dayside at ~59° compared to dawnside and nightside respectively. The latitudinal shift of FAC range is better correlated to IMF BZ in northern hemisphere dusk-dawn magnetic local time (MLT) sectors than in southern hemisphere. The FAC range latitudinal shifts responds better to dynamic pressure in the duskside northern hemisphere and dawnside southern hemisphere than in southern hemisphere dusk sector and northern hemisphere dawn sector respectively. FAC range exhibits a good correlation with dynamic pressure in the dayside (nightside) southern (northern) hemispheres depicting possible electrodynamic similarity at day-night MLT sectors in the opposite hemispheres.

Study of Variation of Polar Cap Potential During Geomagnetic Storm Events of 24 November 2001 and 24 August 2005 as Observed From LFM and BATS‐R‐US Simulation

AbstractIn this paper we examine variation of polar cap potential (PCP) during two storm events that occurred on 24 November 2001 and 24 August 2005 using Lyon‐Fedder‐Mobarry (LFM) and Block‐Adaptive‐Tree‐Solarwind_Roe‐Upwind‐Scheme (BATS‐R‐US) simulations and compare it to Weimer model. These events were simulated for zero, pure By, pure Bz, and full IMF conditions separately, and the PCP obtained were compared with the zero IMF PCP value as a baseline (viscous) potential. For southward IMF, PCP is defined as sum of reconnection and viscous, whereas for northward IMF, it is peak to peak potential, which either will be viscous potential or reconnection potential, whichever is larger. Both events were simulated for a constant ionospheric conductivity of 5 mhos and the variation of PCP was found to be consistent with previous literatures. Furthermore, we found that BATS‐R‐US PCP fluctuated similar to LFM PCP for most parts although their PCP values did not exactly match. We observed that BATS‐R‐US PCP also goes below viscous value for northward IMF condition, something which was observed previously in LFM simulation only. We also found that BATS‐R‐US PCP is more sensitive to smaller fluctuation of IMF compared to LFM. For 24 August 2005 event, we found the PCP reach up to 550 and 440 kV and the viscous potential reached up to 120 and 110 kV for BATS‐R‐US and LFM, respectively. Similarly, for 24 November 2001 event PCP reached up to 800 and 400 kV and viscous potential reached up to 300 and 200 kV, respectively, for BATS‐R‐US and LFM.

The Influence of Geomagnetic Storm of 7‐8 September 2017 on the Swarm Precise Orbit Determination

AbstractWe analyze a recent geomagnetic storm event on 7‐8 September 2017 to investigate the impact of geomagnetic storm on the precise orbit determination (POD) of Swarm constellation. The storm time performance of POD is analyzed. The quality of Swarm orbits are severely degraded during the storm main phase on 8 September and the maximum precision degradation reached over 10 cm. The enhanced thermospheric mass density at Swarm altitude during the storm enlarges the atmosphere drag for low Earth orbit satellites, which makes main contributions to the storm time degradation of Swarm orbit. This negative effect of enhanced atmosphere drag on the orbit estimation is mostly suppressed by estimating a more frequent atmosphere drag parameter. The higher‐order ionospheric effects on the POD of Swarm are also analyzed. The vertical total electron content derived from the Swarm onboard Global Positioning System receiver presents a larger enhancement on the dayside at low latitude and midlatitude during the storm main phase. This leads to an increase in the high‐order ionospheric effects, especially in the second‐order terms. No evident precision improvement is observed after correcting the high‐order ionospheric effects. The results demonstrate that during this geomagnetic storm, the enhanced thermospheric neutral density serves as a stronger error source than the enhanced ionospheric plasma density for the low Earth orbit satellite orbit determination processing.

Radiative cooling due to NO at 5.3 [formula omitted]m emission as observed by TIMED/SABER over Asian sector

The effect of geomagnetic storms on the peak emission of NO Volume Emission Rate (NO VER) at 5.3 μm, in mesosphere and lower thermosphere (MLT) region, is studied over the Asian sector during 26–29 September 2011 (storm 1) and 18–21 February 2014 (storm 2). The data for peak emission of NO VER is obtained from SABER instrument onboard the NASA’s TIMED satellite. The SABER retrieved data along with the neutral densities obtained from NRLMSISE-00 model have been used to study the latitudinal and longitudinal variation of peak NO VER during the storm period. The variations induced in the peak emission of NO VER is understood with the help of fluctuations in neutral species and the resulting changes in chemistry. It has been found that the peak emission of NO VER is strongly influenced by the storm conditions. The peak emission of NO VER at 5.3 μm is found to be maximum at higher latitudes during the storms. However, the magnitude of peak NO VER gradually decreases towards the equator during the storms. The modeled atomic oxygen number density shows depletion at the higher latitudes corresponding to peak altitude of NO VER. There is a negative correlation between the peak emission of NO VER and Dst index during the main phase of the storm. The peak emission of NO VER and modeled atomic oxygen number density shows the positive correlation at the equator region, while negative correlation at the higher latitudes. At higher latitudes modeled atomic oxygen number density shows positive correlation with Dst index, while negative correlation at the equator. The correlation factors obtained between various parameters related to the storm time radiative cooling strongly support the existing understanding of the variation of NO VER during extreme space weather events.