Coordinated Cluster and Double Star observations of the dayside magnetopause near magnetic noon

Frederic Pitout (1) , M.W. Dunlop (2) , P. Escoubet (3)

1 MPE - Max-Planck-Institut für Extraterrestrische Physik
2 RAL Space - Space Science and Technology Department [Didcot]
3 ESTEC - European Space Research and Technology Centre

We present results of a Double Star TC-1/Cluster conjunction where Double Star is at the magnetopause, near the equatorward edge of the Southern hemisphere's polar cusp, while Cluster sits at the poleward edge of the same cusp. This configuration makes it possible to compare observations at different places of the magnetopause, in more or less the same magnetic local time but at different latitudes. In this paper, we report on and discuss three interesting events. First, a FTE is observed at TC-1 and not at Cluster; we discuss the implications this has on the evolution of FTEs. Then, a variation in the solar wind pressure makes the magnetosphere expend slightly and the satellites, then out in the sheath, get near the magnetopause. The delay between Double Star and Cluster suggests that a rarefaction wave propagates along the magnetopause. This rarefaction wave made Cluster move close to the magnetopause, where a rotational discontinuity is observed. At last, a northward turning of the magnetosheath magnetic field is observed at TC-1 and a reverse FTE is subsequently seen at Cluster, suggesting that magnetic reconnection is fast to start at a given location following a change in the IMF orientation. We put our observations in the global context of solar wind /magnetosphere interactions, by means of magnetic reconnection or surface waves along the magnetopause.

Frederic Pitout, M.W. Dunlop, P. Escoubet. Coordinated Cluster and Double Star observations of the dayside magnetopause near magnetic noon. The Western Pacific Geophysics Meeting (WPGM), Jul 2006, Beijing, China. ⟨insu-00367925⟩