Global characteristics of Pc1 magnetic pulsations during solar cycle 23 deduced from CHAMP data

Park, J.; Lühr, Hermann; Rauberg, Jan

doi:10.5194/angeo-31-1507-2013

Cited by 46 publications

(80 citation statements)

References 52 publications

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“…The "mean field" in our case is derived dynamically from the in situ measurements, low-pass filtered with a cutoff period of 60 s. From the smoothed ambient field readings we compute the local declination and inclination, which are needed to calculate the field components in the MFA frame (e.g. Park et al, 2013). A limitation of this approach is that large-scale features (> 200 km) are suppressed by the way the mean field is determined.…”

Section: Field-aligned Current Calculationmentioning

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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Section: Field-aligned Current Calculationmentioning

confidence: 99%

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

et al. 2014

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“…A more detailed description of that frame can be found in Park et al (2013). In this frame x and y 84 signals are generally small and z comprises the total field strength.…”

Section: Processing Approach and Spectral Overview 71mentioning

confidence: 99%

Noise features of the CHAMP vector magnetometer in the 1–25 Hz frequency range

Yin

Lühr

Park

et al. 2015

Sensors and Actuators A: Physical

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“…MFA coordinates are defined as follows: the z component (hereafter "parallel" component) is aligned with the mean field, the y component (hereafter "zonal" component) is perpendicular to the mean field and parallel to the horizontal plane (pointing eastward), and the x component (hereafter "meridional" component) completes the triad, pointing outward. For the transformation of magnetic field data in sensor coordinates to the MFA frame we have used the same approach as described in Park et al [14]. In the MFA frame the two transverse components are usually small outside the auroral oval.…”

Section: Instrumentation and Data Processing The Champ 50 Hz Datamentioning

confidence: 99%

Systematic study of intermediate-scale structures of equatorial plasma irregularities in the ionosphere based on CHAMP observations

Lühr¹,

Xiong²,

Park³

et al. 2014

Front. Physics

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Equatorial spread-F ionospheric plasma irregularities on the night-side, commonly called equatorial plasma bubbles (EPB), include electron density variations over a wide range of spatial scales. Here we focus on intermediate-scale structures ranging from 100 m to 10 km, which play an important role in the evolution of EPBs. High-resolution CHAMP magnetic field measurements sampled along north-south track at 50 Hz are interpreted in terms of diamagnetic effect for illustrating the details of electron density variations. We provide the first comprehensive study on intermediate-scale density structures associated with EPBs, covering a whole solar cycle from 2000 to 2010. The large number of detected events, almost 9000, allows us to draw a detailed picture of the plasma fine structure. The occurrence of intermediate-scale events is strongly favored by high solar flux. During times of F10.7 <100 sfu practically no events were observed. The longitudinal distribution of our events with respect to season or local time agrees well with that of the EPBs, qualifying the fine structure as a common feature, but the occurrence rates are smaller by a factor of 4 during the period 2000-2005. Largest amplitude electron density variations appear at the poleward boundaries of plasma bubbles. Above the dip-equator recorded amplitudes are small and fall commonly below our resolution. Events can generally be found at local times between 19 and 24 LT, with a peak lasting from 20 to 22 LT. The signal spectrum can be approximated by a power law. Over the frequency range 1-25 Hz we observe spectral indices between −1.4 and −2.6 with peak occurrence rates around −1.9. There is a weak dependence observed of the spectral index on local time. Toward later hours the spectrum becomes shallower. Similarly for the latitude dependence, there is a preference of shallower spectra for latitudes poleward of the ionization anomaly crest. Our data suggest that the generation of small plasma structures is part of the early stage EPB development, during times when the vertical plasma drift surpasses a certain threshold.

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Global characteristics of Pc1 magnetic pulsations during solar cycle 23 deduced from CHAMP data

Cited by 46 publications

References 52 publications

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

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

Noise features of the CHAMP vector magnetometer in the 1–25 Hz frequency range

Systematic study of intermediate-scale structures of equatorial plasma irregularities in the ionosphere based on CHAMP observations

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