 |
| Titel |
A global study of hot flow anomalies using Cluster multi-spacecraft measurements |
| VerfasserIn |
G. Facskó, Z. Nemeth, G. Erdős, A. Kis, I. Dandouras |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
0992-7689
|
| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 27, no. 5 ; Nr. 27, no. 5 (2009-05-05), S.2057-2076 |
| Datensatznummer |
250016525
|
| Publikation (Nr.) |
 copernicus.org/angeo-27-2057-2009.pdf |
|
|
|
|
|
| Zusammenfassung |
| Hot flow anomalies (HFAs) are studied using observations of the magnetometer
and the plasma instrument aboard the four Cluster spacecraft. We study
several specific features of tangential discontinuities on the basis of
Cluster measurements from the time periods of February–April 2003, December
2005–April 2006 and January–April 2007, when the separation distance of
spacecraft was large. The previously discovered condition
(Facskó et al., 2008) for forming HFAs is confirmed,
i.e. that the solar wind speed and fast magnetosonic Mach number values are
higher than average. Furthermore, this constraint is independent of the
Schwartz et al. (2000)’s condition for HFA formation. The existence of
this new condition is confirmed by simultaneous ACE magnetic field and solar
wind plasma observations at the L1 point, at 1.4 million km distance from the
Earth. The temperature, particle density and pressure parameters observed at
the time of HFA formation are also studied and compared to average values of
the solar wind plasma. The size of the region affected by the HFA was
estimated by using two different methods. We found that the size is mainly
influenced by the magnetic shear and the angle between the discontinuity
normal and the Sun-Earth direction. The size grows with the shear and (up to
a certain point) with the angle as well. After that point it starts
decreasing. The results are compared with the outcome of recent hybrid
simulations. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|