Similarities and differences in low‐ to middle‐latitude geomagnetic indices

Katus, R. M.; Liemohn, Michael W.

doi:10.1002/jgra.50501

Cited by 34 publications

(43 citation statements)

References 38 publications

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“…It involves searching for negative peaks in Dst (DstMin < −50 nT), finding the maximum Dst within 24 h prior to DstMin for MPO and 96 h after DstMin for the end of recovery phase, and looking for a sharp increase in Dst within 8 h prior to MPO for storm sudden commencement (SSC). Using this procedure Katus and Liemohn (2013) identified 697 storms in Kyoto Dst in 24 years ) while the present procedure identified nearly the same number of storms (761) but in 50 years . The identified storms are 30% more in Kyoto Dst (761) than in USGS Dst (587) mainly due to the baseline offset (or difference) between the two indices that arises from the different methods of removal of the secular and Sq variations calculated in different ways in the two indices (e.g., Sugiura and Kamei 1991;Love and Gannon 2009), which also leads to storm time differences (Fig.…”

Section: Discussionmentioning

confidence: 77%

“…Detailed studies of the offset are beyond the scope of the present paper. Katus and Liemohn (2013) also found large differences between the storms in Kyoto Dst, USGS Dst and SYM-H indices especially at DstMin, on average up to 20% of the peak DstMin, though the storms in the indices are highly correlated.…”

Section: Discussionmentioning

confidence: 83%

“…These are major advantages of the automated storm selection procedure. Recently, Katus and Liemohn (2013) reported another automated storm selection procedure. It involves searching for negative peaks in Dst (DstMin < −50 nT), finding the maximum Dst within 24 h prior to DstMin for MPO and 96 h after DstMin for the end of recovery phase, and looking for a sharp increase in Dst within 8 h prior to MPO for storm sudden commencement (SSC).…”

Section: Discussionmentioning

confidence: 99%

“…Geomagnetic indices such as the low-latitude Dst (disturbance storm time) index have been developed to study geomagnetic storms (e.g., Sugiura 1964;Sugiura and Kamei 1991;Love and Gannon 2009); see also Rostoker (1972). The storms have been studied for over 150 years using geomagnetic data, indices and models (e.g., Sabine 1856;Mayaud 1978;Iyemori 1980;Takalo et al 1995;Siscoe and Crooker 1996;Daglis 1997;Kamide et al 1998;Gonzalez et al 1999;Cliver et al 2000;Fok et al 2001;Liemohn et al 2001;O'Brien and McPherron 2002;Vijaya Lekshmi et al 2011;Yakovchouk et al 2012;Zhao and Zong 2012;Katus and Liemohn 2013;Kumar et al 2015;Lakhina and Tsuritani 2016). From these studies, it is known that the occurrence and intensity of the storms vary with solar activity, time of year and time of day.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Discussionmentioning

confidence: 77%

Section: Discussionmentioning

confidence: 83%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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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“…Note more short-scale variations in B z during the HSS proper as compared with the pre-event background. Figure 1k presents the pressure-corrected high-resolution SYM-H index (Burton et al 1975;Gonzalez et al 1994;Katus & Liemohn 2013). There is a negative SYM-H bay observed at the beginning of the CIR encounter.…”

Section: Observations and Empirical Estimations Of External Driving Dmentioning

confidence: 99%

Estimation of energy budget of ionosphere-thermosphere system during two CIR-HSS events: observations and modeling

Verkhoglyadova

Meng

Mannucci

et al. 2016

J. Space Weather Space Clim.

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We analyze the energy budget of the ionosphere-thermosphere (IT) system during two High-Speed Streams (HSSs) on 22-31 January, 2007 (in the descending phase of solar cycle 23) and 25 April-2 May, 2011 (in the ascending phase of solar cycle 24) to understand typical features, similarities, and differences in magnetosphere-ionosphere-thermosphere (IT) coupling during HSS geomagnetic activity. We focus on the solar wind energy input into the magnetosphere (by using coupling functions) and energy partitioning within the IT system during these intervals. The Joule heating is estimated empirically. Hemispheric power is estimated based on satellite measurements. We utilize observations from TIMED/SABER (Thermosphere-IonosphereMesosphere Energetics and Dynamics/Sounding of the Atmosphere using Broadband Emission Radiometry) to estimate nitric oxide (NO) and carbon dioxide (CO 2 ) cooling emission fluxes. We perform a detailed modeling study of these two similar HSS events with the Global Ionosphere-Thermosphere Model (GITM) and different external driving inputs to understand the IT response and to address how well the model reproduces the energy transport. GITM is run in a mode with forecastable inputs. It is shown that the model captures the main features of the energy coupling, but underestimates NO cooling and auroral heating in high latitudes. Lower thermospheric forcing at 100 km altitude is important for correct energy balance of the IT system. We discuss challenges for a physics-based general forecasting approach in modeling the energy budget of moderate IT storms caused by HSSs.

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Solar filament impact on 21 January 2005: Geospace consequences

et al. 2014

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On 21 January 2005, a moderate magnetic storm produced a number of anomalous features, some seen more typically during superstorms. The aim of this study is to establish the differences in the space environment from what we expect (and normally observe) for a storm of this intensity, which make it behave in some ways like a superstorm. The storm was driven by one of the fastest interplanetary coronal mass ejections in solar cycle 23, containing a piece of the dense erupting solar filament material. The momentum of the massive solar filament caused it to push its way through the flux rope as the interplanetary coronal mass ejection decelerated moving toward 1 AU creating the appearance of an eroded flux rope (see companion paper by Manchester et al. (2014)) and, in this case, limiting the intensity of the resulting geomagnetic storm. On impact, the solar filament further disrupted the partial ring current shielding in existence at the time, creating a brief superfountain in the equatorial ionosphere-an unusual occurrence for a moderate storm. Within 1 h after impact, a cold dense plasma sheet (CDPS) formed out of the filament material. As the interplanetary magnetic field (IMF) rotated from obliquely to more purely northward, the magnetotail transformed from an open to a closed configuration and the CDPS evolved from warmer to cooler temperatures. Plasma sheet densities reached tens per cubic centimeter along the flanks-high enough to inflate the magnetotail in the simulation under northward IMF conditions despite the cool temperatures. Observational evidence for this stretching was provided by a corresponding expansion and intensification of both the auroral oval and ring current precipitation zones linked to magnetotail stretching by field line curvature scattering. Strong Joule heating in the cusps, a by-product of the CDPS formation process, contributed to an equatorward neutral wind surge that reached low latitudes within 1-2 h and intensified the equatorial ionization anomaly. Understanding the geospace consequences of extremes in density and pressure is important because some of the largest and most damaging space weather events ever observed contained similar intervals of dense solar material.

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Similarities and differences in low‐ to middle‐latitude geomagnetic indices

Cited by 34 publications

References 38 publications

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

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

Estimation of energy budget of ionosphere-thermosphere system during two CIR-HSS events: observations and modeling

Solar filament impact on 21 January 2005: Geospace consequences

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