Statistical analysis of SC‐associated geosynchronous magnetic field perturbations

Park, J.‐S.; Kim, K.-H.; Lee, D.-H.; Araki, Tohru; Lee, E.; Jin, Ho

doi:10.1029/2012ja017648

Cited by 12 publications

(30 citation statements)

References 29 publications

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“…This distribution characteristic is consistent with results from Park et al []. The reason for this kind of distribution is suggested to be related to dawn‐dusk asymmetric response to enhancement of solar wind dynamics [ Park et al , , ].…”

Section: Summary and Discussionsupporting

confidence: 91%

Geomagnetic storms and EMIC waves: Van Allen Probe observations

Wang

Yuan

et al. 2016

JGR Space Physics

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Utilizing the data from magnetometer instrument of Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) suite on board Van Allen Probe A, the occurrences of electromagnetic ion cyclotron (EMIC) waves during geomagnetic storms and nonstorm periods are investigated. The 270 EMIC wave events and 76 geomagnetic storms were identified during the period under research, from 8 September 2012 to 30 April 2014, when the apogee of Van Allen Probe A covered all the magnetic local time (MLT) sectors. Fifty of the 76 storms observed 124 EMIC wave events, of which 80 are found in the recovery phase, more than those observed in the main phase. Majority EMIC wave events (~54%) were observed during the nonstorm periods. Occurrence rates of EMIC waves as a function of L and MLT during different geomagnetic conditions are also examined, whose peaks in main phase are higher than those in recovery phase. However, occurrences of EMIC waves in recovery phase distribute more uniformly than those do in main phase. Evolution of the distribution characteristics of EMIC waves respect to L and MLT in different geomagnetic phases is investigated, consistent with that of the plasmasphere during geomagnetic storms, implying that the cold and dense plasma in the plasmasphere or plasmaspheric plume play a significant role in the generation of EMIC waves in the inner magnetosphere. Few EMIC waves in the dayside sector during the preonset periods are observed, suggesting that the effect of solar wind dynamic pressure on the generation of EMIC waves in the inner magnetosphere in those periods is not so significant as expected.

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Section: Summary and Discussionsupporting

confidence: 91%

Geomagnetic storms and EMIC waves: Van Allen Probe observations

Wang

Yuan

et al. 2016

JGR Space Physics

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“…Then, geosynchronous magnetic fields in the prenoon sector should be more sensitive to a change in P sw than in the postnoon sector. Recently, we reported that the normalized sudden commencement amplitudes in the prenoon sector (MLT = 0900–1200) are larger than those in the postnoon sector (MLT = 1200–1500) at geosynchronous orbit [see Park et al , , Figure ]. This indicates that the prenoon sector is more compressed than in the postnoon sector at geosynchronous orbit.…”

Section: Discussionmentioning

confidence: 99%

EMIC waves observed at geosynchronous orbit under quiet geomagnetic conditions (Kp ≤ 1)

et al. 2016

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We statistically study the local time distribution of the helium band electromagnetic ion cyclotron (EMIC) waves observed at geosynchronous orbit when geomagnetic activity was low (Kp ≤ 1). In order to identify the geosynchronous EMIC waves, we use high time resolution magnetic field data acquired from GOES 10, 11, and 12 over a 2 year period from 2007 and 2008 and examine the local time distribution of EMIC wave events. Unlike previous studies, which reported high EMIC wave occurrence in the postnoon sector with a peak around 1500–1600 magnetic local time (MLT) during magnetically disturbed times (i.e., storm and/or substorm), we observed that quiet time EMIC waves mostly occur in a region from morning (∼0600 MLT) to afternoon (∼1600 MLT) with a peak around 1100–1200 MLT. To investigate whether the quiet time EMIC wave occurrence has a causal relationship with magnetospheric convection enhancement or solar wind dynamic pressure variations, we performed a superposed epoch analysis of solar wind parameters (solar wind speed, density, dynamic pressure, and interplanetary magnetic field Bz) and geomagnetic indices (AE and SYM‐H). From the superposed epoch analysis we found that solar wind dynamic pressure variation is a more important parameter than AE and SYM‐H for quiet time EMIC wave occurrence.

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“…For example, the preference of magnetic local time has been widely observed when the magnetosphere is compressed by a shock. The amplitude of SI (mostly in magnetic B z ) has highest values at local noon equatorial latitudes and decreases from noon toward midnight; no explicit response or even negative response is found in the nightside [ Kokubun , ; Borodkova et al , ; Villante and Piersanti , ; Park et al , ]. Statistical analysis also indicated that the electric field fluctuation is stronger by a factor of 5 to 10 near the noon than in the nightside sector [ Laakso and Schmidt , ].…”

Section: Discussionmentioning

confidence: 99%

Prompt GPS TEC response to magnetospheric compression

et al. 2017

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A new type of total electron content (TEC) variation was observed when an interplanetary shock impacted on the Earth's magnetosphere on 17 March 2015. With hundreds of ground‐based Global Positioning System (GPS) receivers, instantaneous TEC impulses were detected in the signals from four GPS satellites cruising in the dayside equatorial magnetosphere. Despite the small amplitude (0.3 TECU), the impulses were synchronously registered by receivers spreading from low to middle latitudes on the ground; they lasted for several minutes, during which period the interplanetary magnetic field (IMF) kept northward. The TEC impulses therefore discriminate themselves from usual traveling ionospheric disturbances and exclude possible effects from the southward IMF‐driven magnetic storm. We suggest that the TEC variation is caused by shock‐induced magnetospheric compression, which moves plasma earthward in the dayside plasmasphere. As a result, some plasma outside of GPS orbit (4.2 RE) is moved to the inside and contributes to the plasma content traversed by GPS raypath. The GPS TEC technique thus exhibits an unprecedented capability to capture small tremor of the magnetosphere, and with the dense receiver network on the ground it can be a feasible tool for remote sensing of the plasma dynamics around 4.2 RE.

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Statistical analysis of SC‐associated geosynchronous magnetic field perturbations

Cited by 12 publications

References 29 publications

Geomagnetic storms and EMIC waves: Van Allen Probe observations

Geomagnetic storms and EMIC waves: Van Allen Probe observations

EMIC waves observed at geosynchronous orbit under quiet geomagnetic conditions (Kp ≤ 1)

Prompt GPS TEC response to magnetospheric compression

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