New plasmapause model derived from CHAMP field-aligned current signatures

Heilig, B.; Lühr, Hermann

doi:10.5194/angeo-31-529-2013

Cited by 23 publications

(43 citation statements)

References 25 publications

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“…To check this assumption we compare the day-to-day variations of the L value of the Pc2-3 occurrence rate maximum (L Pc2-3 ) with the plasmapause position determined from the Carpenter formula L pp = 5.7 − 0.47 Kp (Carpenter and Anderson, 1992). For low and moderate Kp, the empirical formula obtained from CHAMP observations by Heilig and Lühr (2013) gives similar results. Two-day mean values of L Pc2-3 , determined from CHAMP measurements in the 00:00-06:00 MLT sector in the Southern Hemisphere during the best data coverage for 2 months, are shown in Fig.…”

Section: An Example Of a Pc2-3 Event Recordedmentioning

confidence: 96%

“…Moreover, spatial structures do exist in the ionospheric F layer and contribute to the ULF spectrum of magnetic field oscillations recorded by CHAMP. A detailed analysis of spatial structures near the plasmapause has been done by Heilig and Lühr (2013). Le et al (2011) observed similar wavepackets at the low-orbiting ST-5 satellites.…”

Section: N Yagova Et Al: Mm100 Champ and Themis Observationsmentioning

confidence: 99%

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Pc2-3 geomagnetic pulsations on the ground, in the ionosphere, and in the magnetosphere: MM100, CHAMP, and THEMIS observations

Yagova

Heilig²,

Fedorov

2015

Ann. Geophys.

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Abstract. We analyze Pc2-3 pulsations recorded by the CHAMP (CHAllenging Minisatellite Payload) satellite in the F layer of the Earth's ionosphere, on the ground, and in the magnetosphere during quiet geomagnetic conditions. The spectra of Pc2-3 pulsations recorded in the F layer are enriched with frequencies above 50 mHz in comparison to the ground Pc2-3 spectra. These frequencies are higher than the fundamental harmonics of the field line resonances in the magnetosphere. High quality signals with dominant frequencies 70-200 mHz are a regular phenomenon in the F layer and in the magnetosphere. The mean latitude of the maximum Pc2-3 occurrence rate lies at L ≈ 3.5 in the F layer, i.e., inside the plasmasphere. Day-to-day variations of the L value of the CHAMP Pc2-3 occurrence rate maximum follow the plasmapause day-to-day variations. Polarization and amplitude of Pc2-3s in the magnetosphere, in the ionosphere, and on the ground allow us to suggest that they are generated as fast magnetosonic (FMS) waves in the outer magnetosphere and are partly converted into shear Alfven waves near the plasmapause. The observed ground-to-ionosphere amplitude ratio during the night is interpreted as a result of the Alfven wave transmission through the ionosphere. The problem of wave transmission through the ionosphere is solved theoretically by means of a numerical solution of the full-wave equation for the Alfven wave reflection from and transmission through a horizontally stratified ionosphere. The best agreement between the calculated and measured values of the ground-to-ionosphere amplitude ratio is found for k = 5 × 10 −3 km −1 , i.e., the observed ground-to-ionosphere amplitude ratio corresponds to a wave spatial scale which could provide a Doppler shift within a few percent of the apparent frequency of the Pc2-3 pulsations as recorded by a loworbiting spacecraft.

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Section: An Example Of a Pc2-3 Event Recordedmentioning

confidence: 96%

Section: N Yagova Et Al: Mm100 Champ and Themis Observationsmentioning

confidence: 99%

Pc2-3 geomagnetic pulsations on the ground, in the ionosphere, and in the magnetosphere: MM100, CHAMP, and THEMIS observations

Yagova

Heilig²,

Fedorov

2015

Ann. Geophys.

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“…Empirical L PP has been estimated by examining groundbased whistler observations, in situ satellite density measurements (e.g., ISEE, CRRES), field-aligned current signature observations (CHAMP) and geomagnetic indices (Chappell et al, 1970b;Horwitz et al, 1986;Carpenter and Anderson, 1992;Gallagher et al, 2000;Moldwin et al, 2002;O'Brien and Moldwin, 2003;Heilig and Lühr, 2013).…”

Section: Published By Copernicus Publications On Behalf Of the Europementioning

confidence: 99%

The relationship between plasmapause, solar wind and geomagnetic activity between 2007 and 2011

Verbanac

Pierrard

Bandić³

et al. 2015

Ann. Geophys.

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Abstract. Taking advantage of the Cluster satellite mission and especially the observations made by the instrument WHISPER to deduce the electron number density along the orbit of the satellites, we studied the relationships between the plasmapause positions (L PP ) and the following L PP indicators: (a) solar wind coupling functions B z (Z component of the interplanetary magnetic field vector, B, in GSM system), BV (related to the interplanetary electric field; B is the magnitude of the interplanetary magnetic field vector, V is solar wind velocity), and d mp /dt (which combines different physical processes responsible for the magnetospheric activity) and (b) geomagnetic indices Dst, Ap and AE. The analysis is performed separately for three magnetic local time (MLT) sectors (Sector1 -night sector (01:00-07:00 MLT); Sector2 -day sector (07:00-16:00 MLT); Sector3 -evening sector (16:00-01:00 MLT)) and for all MLTs taken together. All L PP indicators suggest the faster plasmapause response in the postmidnight sector. Delays in the plasmapause responses (hereafter time lags) are approximately 2-27 h, always increasing from Sector1 to Sector3. The obtained fits clearly resolve the MLT structures. The variability in the plasmapause is the largest for low values of L PP indicators, especially in Sector2. At low activity levels, L PP exhibits the largest values on the dayside (in Sector2) and the smallest on the postmidnight side (Sector1). Displacements towards larger values on the evening side (Sector3) and towards lower values on the dayside (Sector2) are identified for enhanced magnetic activity. Our results contribute to constraining the physical mechanisms involved in the plasmapause formation and to further study the still not well understood related issues.

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“…For current calculation we make use of the two transverse components in a mean field-aligned (MFA) coordinate system, which is suitable for FAC calculation (Heilig and Lühr, 2013). In the MFA frame the z component is aligned with the ambient magnetic field direction; the y component lies in the horizontal plane and is orthogonal to z, pointing towards magnetic east; and the x component completes the triad and points outwards.…”

Section: Field-aligned Current Calculationmentioning

confidence: 99%

“…The magnetic apex latitude (Richmond, 1995) used here facilitates a mapping of the detected boundary location at satellite height along geomagnetic field lines down to magnetic latitudes at E layer altitudes (∼ 110 km). Following the work of Heilig and Lühr (2013), a variable S has been used to represent the FAC intensity, which is defined as S = log 10 j 2 20s .…”

Section: Determining the Auroral Oval Boundariesmentioning

confidence: 99%

Determining the boundaries of the auroral oval from CHAMP field-aligned current signatures – Part 1

et al. 2014

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Abstract. In this paper we present the first statistical study on auroral oval boundaries derived from small-and mediumscale field-aligned currents (FACs, < 150 km). The dynamics of both the equatorward and poleward boundaries is deduced from 10 years of CHAMP (CHAllenging Minisatellite Payload) magnetic field data (August 2000-August 2010). The approach for detecting the boundaries from FACs works well under dark conditions. For a given activity level the boundaries form well-defined ellipses around the magnetic pole. The latitudes of the equatorward and poleward boundaries both depend, but in different ways, on magnetic activity. With increasing magnetic activity the equatorward boundary expands everywhere, while the poleward boundary shows on average no dependence on activity around midnight, which seems to be stationary at a value of about 72 • Mlat. Functional relations between the latitudes of the boundaries and different magnetic activity indices have been tested. Best results for a linear dependence are derived for both boundaries with the dayside merging electric field. The other indices, like the auroral electrojet (AE) and disturbance storm time (Dst) index, also provide good linear relations but with some caveats. Toward high activity a saturation of equatorwards expansion seems to set in. The locations of the auroral boundaries are practically independent of the level of the solar EUV flux and show no dependence on season.

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New plasmapause model derived from CHAMP field-aligned current signatures

Cited by 23 publications

References 25 publications

Pc2-3 geomagnetic pulsations on the ground, in the ionosphere, and in the magnetosphere: MM100, CHAMP, and THEMIS observations

Pc2-3 geomagnetic pulsations on the ground, in the ionosphere, and in the magnetosphere: MM100, CHAMP, and THEMIS observations

The relationship between plasmapause, solar wind and geomagnetic activity between 2007 and 2011

Determining the boundaries of the auroral oval from CHAMP field-aligned current signatures – Part 1

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