Earth's lithospheric magnetic field determined to spherical harmonic degree 90 from CHAMP satellite measurements

Maus, Stefan; Rother, M.; Hemant, Kumar; Stolle, Claudia; Lühr, H.; Kuvshinov, Alexey; Olsen, Nils

doi:10.1111/j.1365-246x.2005.02833.x

Cited by 104 publications

(110 citation statements)

References 33 publications

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“…This model includes the main field, the field of the ring current, largescale magnetospheric fields, and the crustal anomalies up to spherical harmonic degree/order 90 (Maus et al, 2006). In particular, the removal of the last term was shown to be important for pulsation studies (Sutcliffe and Lühr, 2003;Vellante et al, 2004).…”

Section: Satellite Datamentioning

confidence: 99%

Comprehensive study of ULF upstream waves observed in the topside ionosphere by CHAMP and on the ground

2007

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Abstract. Based on magnetic field measurements from the satellite CHAMP, a detailed picture could be obtained of the upstream wave (UW) distribution in the topside ionosphere. The low, near-polar orbit of CHAMP, covering all local times, allows the global distribution of this type of pulsation to be revealed. The observations from space are compared to recordings of the ground-based MM100 meridional array covering the latitude range 66 • to 42 • in magnetic coordinates. UWs show up very clearly in the compressional component of the satellite magnetic field data, whereas on the ground, their signature is found in the H component, but it is mixed with oscillations from field line resonant pulsations. Here we first introduce a procedure for an automated detection of UW signatures, both in ground and space data. Then a statistical analysis is presented of UW pulsations recorded during a 132-day period, centred on the autumn 2001 equinox. Observations in the top-side ionosphere reveal a clear latitudinal distribution of the amplitudes. Largest signals are observed at the equator. Minima show up at about 40 • latitude. The coherence between ground and satellite wave signatures is high over wide latitude and longitude ranges. We make suggestions about the entry mechanism of UWs from the foreshock region into the magnetosphere. The clear UW signature in satellite recordings between −60 • and 60 • latitude allows for detailed investigations of the dependence on solar wind conditions. We test the control of solar wind speed, interplanetary magnetic field strength and cone angle on UWs. For the first time, it is possible to derive details of the Doppler-shift effect by modifying the UW frequency from direct observations. The results reconcile foreshock wave generation predictions with near-Earth observations.

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Section: Satellite Datamentioning

confidence: 99%

Comprehensive study of ULF upstream waves observed in the topside ionosphere by CHAMP and on the ground

2007

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“…Vector data recorded in the sensor system were transformed into a mean field-aligned (MFA) coordinate system. The mean field was estimated by the CHAMP based field model POMME 4.1s (Potsdam Magnetic Model of the Earth) developed by Maus et al (2006). This model includes the main field, the crustal anomalies up to spherical harmonic degree/order 90, the field of the ring current, and large-scale magnetospheric fields.…”

Section: Champ Magnetic Datamentioning

confidence: 99%

New plasmapause model derived from CHAMP field-aligned current signatures

Heilig

Lühr

2013

Ann. Geophys.

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We introduce a new model for the plasmapause location in the equatorial plane. The determination of the L-shell bounding the plasmasphere is based on magnetic field observations made by the CHAMP satellite in the topside ionosphere. Related signals are medium-scale field-aligned currents (MSFAC) (some 10 km scale size). The mid-latitude boundary of these MSFACs is used for determining the plasmapause. We are presenting a procedure for detecting the MSFAC boundary. Reliable L-values are obtained on the night side, whenever the solar zenith angle is below 90°. This means, the boundary is not determined well in the 08:00 to 16:00 magnetic local time (MLT) sector. The radial distance of the boundary is closely controlled by the magnetic activity index Kp. Over the Kp range 0 to 9, the L-value varies from 6 to 2 R_E. Conversely, the dependence on solar flux is insignificant. For a fixed Kp level, the obtained L-values of the boundary form a ring on an MLT dial plot with a centre somewhat offset from the geomagnetic pole. This Kp and local time dependent feature is used for predicting the location of the MSFAC boundary at all MLTs based on a single L-value determination by CHAMP. We compared the location of the MSFAC boundary during the years 2001–2002 with the L-value of the plasmapause, determined from in situ observations by the IMAGE spacecraft. The mean difference in radial distance is within a 1 R_E range for all local times and Kp values. The plasmapause is generally found earthward of the FAC boundary, except for the duskside. By considering this systematic displacement and by taking into account the diurnal variation and Kp-dependence of the residuals, we are able to construct an empirical model of the plasmapause location that is based on MSFAC measurements from CHAMP. Our new model PPCH-2012 agrees with IMAGE in situ observations within a standard deviation of 0.79 R_E

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“…Figure 1. Map of the total component of the large-scale lithospheric field for Indonesian region obtained from the MF5 model (Maus, et al 2006) at 5 km altitude. Plate boundaries and subduction zones are indicated as red lines.…”

Section: Discussionmentioning

confidence: 99%

“…Let us note that the existence of a large scale contiguous negative-positive high intensity geomagnetic anomaly pattern along the Java trench has been reported in several occasions. Figure 1 shows the total component of the magnetic anomaly over Indonesian region using the magnetic field model MF5 (Maus, et al 2006) at 5 km altitude. Figure 2 shows a more detailed magnetic anomaly map over the islands along the Java Trench, including the Lombok Island.…”

Section: Introductionmentioning

confidence: 99%

Geomagnetic field anomalies over the Lombok Island region: an attempt to understand the local tectonic changes

Zubaidah

Korte

Mandea

et al. 2009

Int J Earth Sci (Geol Rundsch)

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During the last years, several investigations on the earthquakes and related tectonic structures along the Java trench have been conducted. In this study, we focus on the Lombok Island -West Nusa Tenggara (Indonesia), which lies between the centres of the highest intensity of contiguous negative-positive geomagnetic anomalies in this region. The geological and tectonic structures, however, are not known in detail for this island, whereas a better knowledge of these conditions could lead to better estimate the potential earthquake risks and thus a possible improvement of the existing early warning system.We have performed a ground-based geomagnetic survey at 56 stations in the Lombok Island during October-November 2006 for a detailed mapping and interpretation of geomagnetic anomalies related to the geological and tectonic characteristics. The 2D and 3D magnetic maps show a general geomagnetic anomaly pattern in the Lombok Island which consists of repeated contiguous negative-positive anomalies. Two forward models have been proposed for a profile connecting a strongest apparent dipolar structure. The first model assumes a uniformly magnetized sphere as the source of the anomaly, and could be interpreted as a specific local structure composed by a quite large magnetic body. The second model considers several rocks with different susceptibilities and magnetizations, and could be interpreted as a discontinuity in the geological structures. This model agrees with the local geological surface conditions and the known large scale regional tectonic structure. Therefore, it is used to interpret our results in terms of tectonic characteristics, which suggests the potential existence of a new tectonic element (e.g. a local normal fault) in this region.

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Earth's lithospheric magnetic field determined to spherical harmonic degree 90 from CHAMP satellite measurements

Cited by 104 publications

References 33 publications

Comprehensive study of ULF upstream waves observed in the topside ionosphere by CHAMP and on the ground

Comprehensive study of ULF upstream waves observed in the topside ionosphere by CHAMP and on the ground

New plasmapause model derived from CHAMP field-aligned current signatures

Geomagnetic field anomalies over the Lombok Island region: an attempt to understand the local tectonic changes

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