Ionospheric Response to the St. Patrick's Day Space Weather Events in March 2012, 2013, and 2015 at Southern Low and Middle Latitudes

Kumar, Sushil; Kumar, Vickal V.

doi:10.1029/2018ja025674

Cited by 26 publications

(19 citation statements)

References 47 publications

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“…This storm was second largest geomagnetic storm of the solar cycle 24 after the March 17–18 storm in 2015. It was associated with two CMEs that hit the Earth environment on June 22 (S. Kumar & Kumar, 2019). The IMF B z sharply varied between positive (northward) and negative (southward) values.…”

Section: Resultsmentioning

confidence: 99%

Ionospheric D Region Disturbances due to FAC and LEP Associated With Three Severe Geomagnetic Storms as Observed by VLF Signals

2021

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The effects of one super and two intense storms on three European very low frequency (VLF) transmitter signals received at Algiers (Algeria) station, are presented. Two VLF transmitters (DHO and GQD) are located almost at the same mid‐latitude and third transmitter (NRK) at a high latitude, allowing us to study the latitudinal dependence of the storm effect on the VLF propagation. Two kind of ionospheric disturbances were considered: Direct effect of the field aligned currents (FACs) and the second concerning with the lightning‐induced electron precipitation (LEP) events. The FACs effect was clearly evident on the recorded signal amplitude during the daytime and nighttime. Our analysis of the short‐duration VLF perturbations due to LEP events showed that the ducted and non‐ducted LEPs are the majority of VLF perturbations and a small fraction of LEP events was associated with magnetospherically reflected waves on the high latitude transmitter path (NRK–Algiers). The coincident observation of LEP on the mid‐latitude transmitters (DHO and GQD) signals implies that the disturbance was large as much as the distance between the two transmitters (728 km). The modeling using Long‐Wave Propagation Capability (LWPC) code of LEP associated VLF perturbations considering Gaussian distribution of electron density enhancements, showed a decrease in the D‐region reference height from its usual value 87 km to 83.3 km for ducted LEP and 80.3 km for non‐ducted LEP event and that the non‐ducted event exhibited a wider disturbed region.

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Section: Resultsmentioning

confidence: 99%

Ionospheric D Region Disturbances due to FAC and LEP Associated With Three Severe Geomagnetic Storms as Observed by VLF Signals

2021

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“…It indicated that the positive and negative mechanisms coexisted and competed to each other. The relative contribution varied with location, local time, storm phase, and other factors (Kumar & Kumar, 2019; Liu et al., 2014).…”

Section: Resultsmentioning

confidence: 99%

“…The geomagnetic storms are the disturbances of the Earth's magnetic field, and the impact of solar wind particles enhancement (Buonsanto, 1999; Gonzalez et al., 1994; Kumar & Kumar, 2019). Following geomagnetic storms, the ionosphere also has obvious disturbance.…”

Section: Introductionmentioning

confidence: 99%

Characteristics of Ionospheric Storm on October 13, 2016 at the Greenwich Meridian

Wan

Maruyama

et al. 2021

JGR Space Physics

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The geomagnetic storms are the disturbances of the Earth's magnetic field, and the impact of solar wind particles enhancement (Buonsanto, 1999;Gonzalez et al., 1994;Kumar & Kumar, 2019). Following geomagnetic storms, the ionosphere also has obvious disturbance. It shows the critical frequency of F2-layer (foF2) or total electron content (TEC) changes obviously. The large decrease of foF2 or TEC is the ionospheric negative storm, and the significant increase of foF2 or TEC is referred to as positive storms (Fagundes et al., 2016;Maruyama et al., 2004). In general, 𝐴𝐴 𝐴𝐴 region ionization is positively correlated to the density ratio of atomic oxygen [O] to the molecular nitrogen 𝐴𝐴 [N2] . Prölss (1987) showed that the negative storm was caused by the change of neutral gas composition. The enhanced ratio of 𝐴𝐴 [N2] /[O] would lead to the chemical loss rate increase, so the ionospheric electron density decreased.There are two main physical mechanisms of ionospheric positive storms. The first is the equatorward wind surge or disturbance wind (Fuller-Rowell et al., 1994). Joule heating raises the temperature of the upper thermosphere and ion drag drives high velocity neutral winds. The heat source drives a global disturbance wind. It propagates to low latitudes and even into the opposite hemisphere. The equatorward wind pushes the ionosphere up to high altitudes where the recombination is ineffective. As a result, the electron density increases under sunlit conditions (Maruyama et al., 2004;Zhao et al., 2008). Because the equatorward wind surge blows from high to low latitudes, the ionospheric disturbance has time delay. During quiet days, the neutral winds (or background winds) are poleward in daytime and turn equatorward after sunset. During storms, the neutral winds are the combination of background and disturbance winds. The daytime neutral wind, which is caused by Joule heating in the auroral region, even turns to equatorward (Fuller-Rowell et al., 1994). Different storms have different intensity, local time, and latitude coverage. de Jesus et al. ( 2016) studied a positive ionospheric storm at equatorial, low and middle latitudes in African sector. The factor was the equatorward disturbance winds and huge wind circulations.

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“…It is possible that the empirical high‐latitude drivers of convection and auroral precipitation could yield a pattern smoother than reality, particularly during geomagnetic storms. Although Wuhan is located at low geomagnetic latitude, the mid‐ and low‐latitude ionosphere could also be affected by geomagnetic storms (e.g., Kumar, S., & Kumar, V. V., 2019). This result is supported by the comparison between Figure 7c and 7d that the SD‐WACCM‐X simulated variability is also different from observations under “disturbed” conditions.…”

Section: Discussionmentioning

confidence: 99%

A Comparative Study of Ionospheric Day‐To‐Day Variability Over Wuhan Based on Ionosonde Measurements and Model Simulations

et al. 2021

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Day-today variability is ubiquitous in the ionosphere. Investigating and understanding the behavior is an important subject for the space environment. Previous studies proposed that ionospheric variability is mainly driven by three sources, including variations in solar activity and geomagnetic activity from above and lower atmospheric perturbations from below. Some general features of ionospheric day-today variability have been observed. Forbes et al. (2000) concluded that the variability in F2 peak electron densities (NmF2) at "high frequencies" (periods of several hours-2 days) and "low frequencies" (periods of 2-30 days) were 25%-35% and 15%-20%, respectively, by analyzing ionosonde data over 100 globally distributed stations under geomagnetic quiet conditions (Kp < 1). Rishbeth & Mendillo (2001) analyzed ionosonde data from 13 stations, with geographic (geomagnetic) latitudes range from −52° to +56° (−58° to +51°) during 1957-1990 and found that the day-today variability of NmF2 exhibits an obvious day-night difference in which the relative standard deviation of the mean value is ∼20% by day and ∼33% by night. Observations of incoherent scatter radar (ISR) revealed that the variability strength is height-dependent because photochemistry and plasma dynamics are dominant in different layers of the ionosphere (Moore et al., 2006). In that paper, they chose high latitudes (EISCAT Svalbard, 78.2°N), mid latitudes (Millstone Hill, 42.6°N), and low latitudes (Jicamarca, 12.1°S) ISR facilities. These works also examined the latitudinal dependence of the

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Ionospheric Response to the St. Patrick's Day Space Weather Events in March 2012, 2013, and 2015 at Southern Low and Middle Latitudes

Cited by 26 publications

References 47 publications

Ionospheric D Region Disturbances due to FAC and LEP Associated With Three Severe Geomagnetic Storms as Observed by VLF Signals

Ionospheric D Region Disturbances due to FAC and LEP Associated With Three Severe Geomagnetic Storms as Observed by VLF Signals

Characteristics of Ionospheric Storm on October 13, 2016 at the Greenwich Meridian

A Comparative Study of Ionospheric Day‐To‐Day Variability Over Wuhan Based on Ionosonde Measurements and Model Simulations

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