Astrid-2, an advanced microsatellite for auroral research

Marklund, Göran; Blomberg, Lars G.; Persson, Staffan

doi:10.5194/angeo-19-589-2001

Cited by 17 publications

(13 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This is a reasonable assumption considering that field-aligned electric fields are not expected to occur at the spacecraft altitude. Detailed descriptions of the Astrid-2 satellite and of the EMMA instrument are given by Marklund et al (2001) and Blomberg et al (2004), respectively.…”

Section: Observationsmentioning

confidence: 99%

Statistical study on the occurrence of ASAID electric fields

2010

Self Cite

View full text Add to dashboard Cite

Abstract. The first statistical results on the occurrence of abnormal subauroral ion drifts (ASAID) are presented based on electric and magnetic field measurements from the lowaltitude Astrid-2 satellite. ASAID are narrow regions of rapid eastward ion drifts observed in the subauroral ionosphere. They correspond to equatorward-directed electric fields with peak amplitudes seen to vary between 45 mV/m and 185 mV/m, and with latitudinal extensions between 0.2 • and 1.2 • Corrected Geomagnetic Latitude (CGLat), reaching in some cases up to 3.0 • CGLat.Opposite to subauroral ion drifts (SAID) that are known to be substorm-related, ASAID are seen to occur predominantly during extended periods of low substorm activity. Our results show that ASAID are located in the vicinity of the equatorward edge of the auroral oval, mainly in the postmidnight sector between 23:00 and 03:00 magnetic local time. They are associated with a local current system with the same scale-size as the corresponding ASAID, composed by a region of downward field-aligned currents (FACs) flowing in the ASAID poleward side, and a region of upward flowing FACs in the equatorward side. The FACs have densities between 0.5 and 2.0 µA/m 2 . The data suggest that ASAID do not contribute significantly to the reduction of the ionospheric conductivity. ASAID are seen to have life times of at least 3.5 h.A discussion on possible mechanisms for the generation of ASAID is presented. We speculate that the proximity of the electron to the ion plasma sheet inner boundaries and of the plasmapause to the ring current outer edge, during extended quiet times, is an important key for the understanding of the generation of ASAID electric fields.

show abstract

Section: Observationsmentioning

confidence: 99%

Statistical study on the occurrence of ASAID electric fields

2010

Self Cite

View full text Add to dashboard Cite

show abstract

“…The Miniaturized Electrostatic DUal-top-hat Spherical Analyzer (MEDUSA) was flown aboard the Swedish Astrid-2 microsatellite (Marklund, 2001). The instrument is composed of two spherical top-hat analyzers placed top-to-top with a common 360 • field of view.…”

Section: Instrument Descriptionmentioning

confidence: 99%

A new, unique signature of the true cusp

2001

View full text Add to dashboard Cite

Abstract. The "cusp proper" is generally understood to be the region enclosed by the outermost magnetospheric field lines as they map to low altitudes. It is therefore a weak-field region with continuous contact with magnetosheath plasma. Data from the recent Astrid-2 Swedish microsatellite are presented which show a new, unique signature (dubbed the "true cusp") during cusp crossings that can now be shown to be consistently present and with which one can redefine the physical meaning and topology of the cusp. Similar crossings made by the DE-2, UARS and DMSP-F10 satellites also show this same, unique signature although in most cases the spatial resolution was much less than that of the Astrid-2 MEDUSA spectrometer. The presence of concurrent features of the same scale size as the plasma in the energetic particle, field and wave power data shows that this is a real structural feature and not a coincidental structure among plasma instruments. The persistence of this feature may lend new insight into the dynamics of the cusp and magnetospheric particle entry.

show abstract

“…The data discussed here were taken by the MEDUSA (Miniaturized Electrostatic DUal-tophat Spherical Analyzer), LINDA (Langmuir INterferometer and Density experiment for Astrid-2) and EMMA (Electrical and Magnetic field Monitoring of the Aurora) instruments (see Marklund et al, 2001, for a more detailed description of the Astrid-2 satellite).…”

Section: Instrumentationmentioning

confidence: 99%

Dense ion clouds of 0.1 − 2 keV ions inside the CPS-region observed by Astrid-2

et al. 2001

View full text Add to dashboard Cite

Abstract. Data from the Astrid-2 satellite taken between April and July 1999 show several examples of dense ion clouds in the 0.1-2 keV energy range inside the inner magnetosphere, both in the northern and southern hemispheres. These inner magnetospheric ion clouds are found predominantly in the early morning sector, suggesting that they could have originated from substorm-related ion injections on the night side. However, their location and density show no correlation with Kp, and their energy-latitude dispersion is not easily reproduced by a simple particle drift model. Therefore, these ion clouds are not necessarily caused by substormrelated ion injections. Alternative explanations for the ion clouds are the direct solar wind injections and up-welling ions from the other hemisphere. These explanations do not, however, account for all of the observations.

show abstract

Astrid-2, an advanced microsatellite for auroral research

Cited by 17 publications

References 15 publications

Statistical study on the occurrence of ASAID electric fields

Statistical study on the occurrence of ASAID electric fields

A new, unique signature of the true cusp

Dense ion clouds of 0.1 − 2 keV ions inside the CPS-region observed by Astrid-2

Contact Info

Product

Resources

About