scostep 2010 (stp12) - Leibniz-Institut für Atmosphärenphysik an der ...

STP12 Abstracts
Berlin, 12 - 16 July 2010
SCOSTEP Symposium 2010
Response of the high-latitude magnetosphere to complex interplanetary driving
Koleva Rositza , Bochev Alexander
Solar Terrestrial Influences Institute at the Bulgarian Academy of Sciences (STIL-BAS)
On 22 November 1997 a magnetic cloud reached the earth magnetosphere and produced a
storm with Dst=-75 nT. While the magnetosphere was still in its recovery, a new magnetic
cloud hit the magnetopause, causing the development of a new storm with Dst reaching -108
nT. In the course of this complex two-step storm several substorms developed with AL down
to –1400 nT. The sheath region of the first cloud reached the Earth at ~ 9:50 UT and a pulse
in SW dynamic pressure hit the magnetopause. The high-apogee Interball-1 satellite was in
the tail at ~ -10.6 RE, heading towards perigee. It registered a two times increase of the
magnetic flux about 1.5 – 2 min later. Interball-2 made two scans over the northern polar
hemisphere and observed the development of filed-aligned currents in the dusk sector.
Peculiar magnetopsheric events were observed on 23 November 1997, during the second step
of the storm. While Dst minimum, in the high-latitude magnetosphere Interball-1 registered
intense tailward convection of mantle-like plasma, together with intense bi-directional fluxes
of electrons with magnetosheath energies. Later in the recovery phase in the northern lobe,
within the bi-directional electron fluxes, tailward electrons accelerated near the earth were
identified. Interball-2 registered the development of highly structured intense field-aligned
currents. We compare the observations with the results from Tsyganenko’96 and
Tsyganenko’2005 storm models.