A new parameter of geomagnetic storms for the severity of space weather

Balan, N.; Batista, I. S.; Ram, S. Tulasi; Rajesh, P. K.

doi:10.1186/s40562-016-0036-5

Cited by 23 publications

(25 citation statements)

References 14 publications

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“…The storm sudden commencement took place at around 0445 UT followed by a long MP lasting until 2300 UT. It has an intensity (or minimum Dst or DstMin) of −223 nT and impulse strength (or mean Dst during MP; Balan et al, ) of −113 nT. During the MP, the Brazilian sector (LT = UT − 3) was on the dayside and facilitated to investigate the storm time response of equatorial dynamics and distinct features like the F 3 layer.…”

Section: Resultsmentioning

confidence: 99%

Superfountain Effect Linked With 17 March 2015 Geomagnetic Storm Manifesting Distinct F₃ Layer

et al. 2019

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The existence of an additional stratification in the daytime equatorial ionospheric F region (the F3 layer) was known since the 1940s. However, its characteristics and the underlying physical mechanism have been uncovered only recently. In this paper, we present and discuss the F3 layer characteristics observed by six ionosondes distributed over equatorial and low latitudes (−20° to +25° dip latitudes) in the Brazilian longitude sector during the strongest geomagnetic storm (DstMin = −223 nT) of solar cycle 24, the St. Patrick's Day storm of 17 March 2015. Two eastward prompt penetration electric field (PPEF) events, as seen in equatorial electrojet, occurred during the main phase of the storm on 17 March 2015, a strong one (~100 nT) at around ~1200 UT and a weak one (~50 nT) at around ~1725 UT. Local time variations in the F3 layer occurrence and ionospheric base height (h′F), peak height (hmF), and peak electron density (Nmax) are investigated. Notably, the F3 layer occurred at all six locations, more distinctly during the stronger PPEF event. The large latitudinal extend in the occurrence of the F3 layer in opposite hemispheres (−20° to +25° dip latitudes) covering the equatorial ionization anomaly crests observed for the first time is interpreted in terms of the combined effect of the super plasma fountain generated by the eastward PPEF and storm time equatorward neutral wind.

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Section: Resultsmentioning

confidence: 99%

Superfountain Effect Linked With 17 March 2015 Geomagnetic Storm Manifesting Distinct F₃ Layer

et al. 2019

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“…However, while studying what determines the severity of the space weather, we realized that the storm intensity (DstMin) is insufficient to distinguish between the severe space weather (SvSW) causing electric power outages and telegraph system failures and normal space weather not causing such severe effects (Balan et al, 2014). Our studies also showed that the mean value of Dst during MP (⟨Dst MP ⟩) can indicate the severity of space weather (Balan et al, 2016). It can also be used as a better reference than DstMin in developing a scheme for forecasting SvSW using ICME velocity V and IMF Bz (Balan, Ebihara, et al, 2017).…”

Section: Introductionmentioning

confidence: 85%

IpsDst of Dst Storms Applied to Ionosphere‐Thermosphere Storms and Low‐Latitude Aurora

et al. 2019

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Conventionally, the minimum value of Dst (DstMin) and maximum values of Kp and AE (Kp max and AE max ) representing the geomagnetic storm intensities have been used for investigating space weather in Earth's environment. The present paper uses the derived parameters (IpsDst, IpsKp, and IpsAE) giving the mean values of Dst, Kp, and AE during the main phase (MP) of Dst storms for investigating ionosphere-thermosphere storms and low-latitude (630 nm) aurora. The derived parameters (IpsDst, IpsKp, and IpsAE) representing the impulsive strength of geomagnetic storms seem to have more systematic dependence among themselves than among the intensities (DstMin, Kp max , and AE max ). The ionosphere-thermosphere storms observed by the CHAMP (Challenging Minisatellite Payload) satellite and low-latitude auroras observed by optical imagers are much more intense during high impulsive storms than high intensity storms. In a statistical sense, over 175 positive ionospheric storms (△NmF2) observed in 1985-2005 and the intensity of 20 red auroras observed in 1989-2004 at midlatitudes correlate better with the impulsive parameters than the intensity parameters, with the best correlation being with IpsDst. The mechanism of the impulsive action (high-energy input over a short duration) leading to large IpsDst arises from the impact of fast solar storms (interplanetary coronal mass ejections) with large IMF Bz southward at their front (or shock). The impulsive action results in bright low-latitude auroras and strong ionosphere-thermosphere storms.

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“…It represents the impulsive strength (or strength in short) of Dst storms while DstMin represents their intensity (Balan et al 2014). It (⟨Dst MP ⟩) has been shown to be a unique parameter that can indicate the severity of space weather while the conventional parameter DstMin is insufficient (Balan et al 2016). Average DstMin (=ΣDstMin/number of storms) and average ⟨Dst MP ⟩ = (Σ⟨Dst MP ⟩/number of storms) represent the average intensity and average strength of a certain number of storms during a specific period.…”

Section: Storm Analysismentioning

confidence: 99%

Automatic selection of Dst storms and their seasonal variations in two versions of Dst in 50 years

Balan

Tulasiram

Kamide

et al. 2017

Earth Planets Space

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A computer program is developed to automatically identify the geomagnetic storms in Dst index by applying four selection criteria that minimize non-storm-like fluctuations. The program is used to identify the storms in Kyoto Dst and USGS Dst in 50 years . The identified storms (DstMin ≤ −50 nT) are used to investigate their seasonal variations. It is found that the overall seasonal variations of the storm parameters such as occurrence, average intensity (average DstMin) and average strength (average ⟨Dst MP ⟩) in both versions of Dst exhibit clear semiannual variations with equinoctial maxima and solstice minima; and the maxima and minima in intensity and strength (~±17% each) are less than those in occurrence (~±28%). Wavelet spectra of the storms reveal the existence of distinct semiannual component in four solar cycles (SCs 20-23) and weak longer and shorter-period components in some SCs. The semiannual variation observed also in the mean energy input during the main phase (MP) of the storms estimated from Dst is interpreted in terms of the (1) equinoctial mechanism based on the varying angle between the Earth-Sun line and Earth's dipole axis and (2) Russell-Mcpherron effect based on the varying angle between the GSM Z-axis and GSE Y-axis; and the yearly range of the dipole tilt angle µ (23.2°) involved in the equinoctial mechanism is found larger than the title angle θ (16.3°) involved in the RM effect.

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A new parameter of geomagnetic storms for the severity of space weather

Cited by 23 publications

References 14 publications

Superfountain Effect Linked With 17 March 2015 Geomagnetic Storm Manifesting Distinct F₃ Layer

Superfountain Effect Linked With 17 March 2015 Geomagnetic Storm Manifesting Distinct F₃ Layer

IpsDst of Dst Storms Applied to Ionosphere‐Thermosphere Storms and Low‐Latitude Aurora

Automatic selection of Dst storms and their seasonal variations in two versions of Dst in 50 years

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A new parameter of geomagnetic storms for the severity of space weather

Cited by 23 publications

References 14 publications

Superfountain Effect Linked With 17 March 2015 Geomagnetic Storm Manifesting Distinct F3 Layer

Superfountain Effect Linked With 17 March 2015 Geomagnetic Storm Manifesting Distinct F3 Layer

IpsDst of Dst Storms Applied to Ionosphere‐Thermosphere Storms and Low‐Latitude Aurora

Automatic selection of Dst storms and their seasonal variations in two versions of Dst in 50 years

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Superfountain Effect Linked With 17 March 2015 Geomagnetic Storm Manifesting Distinct F₃ Layer

Superfountain Effect Linked With 17 March 2015 Geomagnetic Storm Manifesting Distinct F₃ Layer